Virtualization Best Practices - How Much Memory Is Enough?

Memory is another key area to consider when you set up virtualization. After all, you can have all the processing power in the world, but unless you have enough memory to run those VMs at the same time, you’ll be stuck with extra processing power.

Hyper-V doesn’t support the concept of allocating more memory than is available in the host system. This prevents you from affecting the performance of the host. (If you started a VM using 4GB on a system with 2GB of RAM, the system would need to use virtual memory to provide the extra memory beyond what was available on the host.) How much memory is necessary for the host? The usual answer applies here: It depends on a number of factors.

Number of VMs running, and their allocated memory. How many VMs will be running on the host, and how much memory will be allocated to each one? The amount of memory each VMs needs is entirely dependent on the workload running within the VM. A SQL Server running in a VM will require much more memory than a departmental file server.

Other workloads running on the host. Although it’s recommended that Hyper-V be the only role running on the host, it’s possible that this won’t be the case. If so, it’s critical that enough memory be available to service all the other workloads running on the system. Refer to the memory requirements of the other workload(s) that will be running on the host, and add that amount to the total amount of memory required for the VM.

Host reserves. It’s recommended that you set aside 512MB of RAM for the host. That memory is used by Hyper-V’s virtualization stack that runs in the parent partition, as well as by any services running in the parent partition. Hyper-V won’t allow a VM to launch unless at least 32MB of RAM is available.

Other VMs (for quick-migration scenarios only). If the host is part of a Windows Server
2008 cluster for quick migration, ensure that there are sufficient resources across all nodes of the cluster in case one node goes down. If a node hosting VMs goes offline for any reason, those VMs will attempt to restart across all other nodes in the cluster. However, if there’s not enough memory on the cluster’s remaining active nodes, the VMs may not be able to start.

Luckily, monitoring the amount of available memory on a Hyper-V host is significantly easier than monitoring processor utilization, because memory utilization appears in Task Manager. You can also monitor the host’s memory utilization using the Memory Available Mbytes counter.

In some rare cases, a VM may not be able to start even when plenty Note of memory is available. This is most commonly seen when large file copies are performed in the parent partition. Microsoft has released a hotfix for this as KB953585.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Virtualization Best Practices - Faster Processors and Performance

In some cases, the speed of the processors leads to better performance. However, this isn’t always the case. For example, let’s consider a VM created by using a physical-to-virtual conversion. This workload was previously running on an older Pentium 3 Xeon processor at 700MHz and is running a custom line-of-business (LOB) application.
Now that it’s in a VM, will the workload run more quickly? Depending on the type of application, it may not. That doesn’t mean the extra processing power from faster processors goes to waste, because it provides extra headroom for workloads to grow and a resource for other VMs. But you do need to take this fact into account.

CPU-Bound or I/O-Bound Workloads
Not all workloads are capped by the processing power available to the VM. Some workloads, such as a SQL Server, are generally bound to a greater extent by the limits of memory and the disk subsystem than by the processor. In this case, buying a faster processor won’t necessarily provide faster performance to the VMs—use the money you save to invest in memory or a faster storage subsystem. Once the host has been deployed, administrators often use management tools to determine how the host is performing. But because of the virtual nature of the processors, monitoring a virtual system isn’t as simple as looking at the Task Manager.

Traditionally, administrators used Windows Task Manager to get a quick glance at what was happening on the system. However, because of the architecture of Hyper-V, Task
Manager doesn’t show the CPU usage of VMs. Task Manager running in the parent partition has no way of displaying that information; instead, you need to use Perfmon.

Perfmon, short for Performance Monitor, is Microsoft’s tool to examine performance data. This data can be as simple as CPU utilization or as complex as context switches between Ring 0 and Ring 3.

By looking at the Hyper-V performance counters through Perfmon, you can determine if the system has room for more VMs or, conversely, if the system is oversubscribed (too many VMs running on the host).

Using Perfmon to monitor the host is easy. From the Start menu, select Administrative Tools, and then select Reliability And Performance Monitor. Click Performance Monitor in the list on the left.

By default, only one item is tracked in Perfmon: % Processor Time. Unless you’re interested in the processor utilization of the parent partition only, you’ll need to add some counters.

The processor-performance counters refer to the number of logical processors (LPs) in the system. A logical processor is a unit of processing power—for example, if you have a system with a single CPU socket and a single-core, non-hyperthreaded processor, you have one LP. Change that processor to a dual-core processor, and you have two LPs. Adding Hyper-Threading? Make it four logical processors.

To add a performance counter, you click the green + sign or press Ctrl-I. A large number of Hyper-V–related performance counters are available, but we’re interested in a couple in particular:

Hyper-V Hypervisor Virtual Processor, % Total Run Time. Under Instances Of Selected
Object, you’ll see a few options. _Total provides a sum of all the VPs allocated to all running VMs. You can also add individual VPs allocated to a VM.

Hyper-V Hypervisor Root Virtual Processor, % Total Run Time. This is the percentage of the time that the logical processors selected are executing instructions in non Hypervisor–based code in the root/parent partition.

Adding these two values gives you the total CPU utilization of the host executing virtualizationrelated code. The closer the value gets to 100%, the more heavily loaded the system is.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Virtualization Best Practices - Choosing a Processor

As of this writing, Hyper-V provides support for up to 24 cores in the parent partition. A core is a unit of processing power. Both Intel and AMD have released processors that consist of multiple processor cores on a single processor. These processors plug into sockets on the computer’s motherboard. Having multiple processor cores on a single die allows even a single-socket system to execute multiple threads of execution at the same time. Although 24 cores sounds like a lot of processing power (and in most cases, it certainly is!), virtualization can easily use all of it.

You must consider three key factors about processors as you work through the planning stages:
• Number of processors in the system
• Number of cores on the processors in the system
• Speed of the processors in the system

Because one of the key features of virtualization is the ability to achieve higher density (running multiple VMs on a single physical host), administrators naturally gravitate toward the processor as a key bottleneck. After all, if a host runs out of processing power, those virtualized workloads may not be able to keep up with the demand being placed on them.

You need to answer a couple of key questions for the host:
• How many processors are necessary for this virtualization host?
• Do the processors need to provide t wo, four, or even six cores per processor?

The answer to these two questions is usually, “It depends.” Two schools of thought apply here, which bring up two more questions: Do you want to use more dual-socket systems, which usually have a lower price point? Or do you want to achieve maximum consolidation by going with quad-socket systems?

The price advantage of dual-socket systems is significant. At the time of writing, you can deploy three physical dual-socket systems for the price of one quad-socket system. You can then cluster those three dual-socket systems together in a high-availability configuration to ensure continuous uptime for the workloads running in the VMs. With the three-system configuration, however, you need to consider some other costs. Having three systems means further expenses for operating system licenses, management software licenses, and the administration of three servers. You also need to factor in the power costs of the three servers.

The other option, which uses only one quad-socket virtualization host, doesn’t provide any sort of backup or high availability—meaning that if the single host goes down, all the virtualized workloads will go down with it. But quad-socket servers generally provide a bit more in terms of expansion and I/O scalability, which could result in additional VMs being deployed on a single host.

Some enterprises are also considering the use of blade servers. Although the up-front cost of the enclosure is higher, the ability to use 14 systems in 7 units of rack space (for example) could be a better fit for some companies. As you can see, there’s no simple answer when you’re deciding on the best configuration for your host.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Virtual Machine Settings

Now that you’ve created a new VM using the wizard, let’s look at the VM’s setting. To do so, select the newly created VM in the Hyper-V Manager, and click Settings. The Settings dialog is broken into two sections: Hardware and Management. The hardware options control the hardware that’s available to the VM, and the management options control the VM’s administrative tasks. We’ll look at all the options available.

Just like a physical system, a VM consists of a variety of (virtual) hardware devices. In the settings for a VM, you can modify that hardware—including adding processors, network adapters, and hard disks.

Add Hardware
You can modify the configuration of the VM by adding hardware, such as a small computer system interface (SCSI) controller or additional network interface, to the VM. The VM must be powered off to add hardware to the VM. After you add the virtual hardware to the VM and power on the VM, the OS will recognize the new hardware.

Hyper-V doesn’t allow direct access to the Basic Input/Output System (BIOS), so the only BIOS settings you can modify are exposed here:

• Num Lock. Selecting this check box triggers Num Lock in the VM to be active on boot.

• Startup Order. This option controls the order in which devices will be queried for boot. The top-most option will be tried first, and if it fails, then the next option will be tried. By default, the boot order is CD, IDE, legacy network adapter, and then floppy.

You can adjust the amount of memory allocated to the VM. This can range from 8MB to the maximum amount of RAM in the system. There are some caveats:

• Once the VM is powered on, the memory is allocated to the VM and can’t be reclaimed until the VM is saved or turned off.

• Memory allocated to a VM can’t be shared. If multiple VMs are running the same OS,
Hyper-V doesn’t provide the capability to share common pages of memory between the VMs.
• Hyper-V doesn’t provide support for allocating more memory than is available on the host. This limits the amount of memory available to allocate to VMs to about 1GB less than the maximum amount of RAM in the host.

The Processor Settings dialog has a number of options. Hyper-V supports up to four virtual processors in the VM. Those virtual processors are scheduled as threads on the physical processors. A VM can’t have more virtual processors allocated than are present in the host. That means that in order to create a four-core VM, the host system must have at least four cores.

The upper limit of total virtual processors you can allocate on a host is eight times the number of logical processors. A single dual-socket, dual-core server (exposing 4 processors to the host) can support a total of 32 virtual processors. You should keep a very close eye on performance to ensure that the system can handle all the running VMs as well as the host.

Additionally, the Processor Settings dialog is where you set the resource-control options for the VM. This dialog includes the following options:

• Virtual Machine Reserve. This reserves a set amount of processor power for the VM. You can think of this reserve as a guaranteed amount of processor resources.

• Virtual Machine Limit. This is a hard cap on the amount of processor power that the VM can take from the host.

• Relative Weight. The relative weight is another method of assigning a value of importance between multiple VMs. You can set this option to any value from 1 to 10,000. If two VMs have the same VM reserves and limits, the VM with a higher relative weight will receive more processing power.

• Processor Functionality. The last check box in the processor settings controls the processor functionality. By selecting this option, you’ll let older OSs, such as Windows NT or earlier, work with Hyper-V.

It’s important to know the differences between a logical processor and a virtual processor. Logical processors are the foundation of today’s multicore processors. A system with a single core and without Hyper-Threading has a single logical processor. Adding additional cores increases the logical processor count. For example, a system with two physical processors, each processor having two cores, has a total logical-processor count of four. A virtual processor is seen on the host as a single thread of execution, which can then be scheduled on any of the logical processors in the system.

IDE Controller
Hyper-V includes a dual-channel IDE controller much like many standard hardware PCs. By default, a single VHD is connected to the primary IDE controller in the primary connection, with a CD/DVD drive connected to the primary connection of the secondary controller.

The VM can boot only from a VHD connected to the IDE controller. Although this does seem strange and counterintuitive for performance reasons, this arrangement is necessary because of the architecture of Hyper-V. The synthetic devices in Hyper-V aren’t seen in the OS without the integration components being installed.

By clicking the IDE controller, you can add a new hard disk or DVD drive to the specific IDE controller. (DVD drives can be connected only to the IDE controllers.) If you select a hard disk, you have a number of options to choose from. At the top, you can select the specific location where the VHD file will be connected the top. If no SCSI controllers have been added to the VM, then you can add the new VHD to one of the pre-existing IDE controllers only. However, if you added a SCSI controller to the VM’s configuration, then the SCSI controller and all available locations will be listed as well.

After you’ve assigned the new VHD to a specific location, you can set up the specifics of the disk. A number of Hard Drive settings are available, including creating a new VHD, using an existing disk, or editing or inspecting an existing disk. The New, Edit, and Inspect buttons all map back to the New Virtual Hard Disk Wizard. This wizard provides a one-stop interface for all tasks having to do with VHD files.

The bottom option, Physical Hard Disk, lets you directly connect a physical logical unit number (LUN) to a VM. This allows the VM to use directly storage volumes that are connected to controllers on the host—including fibre channel, Internet SCSI (iSCSI), or direct-attached SCSI storage. The use of physical hard disks lets you treat your VMs the same way as physical machines, and you get an increase in performance compared to the default dynamically expanding VHD. In order to connect a physical hard disk to a VM, you must mark the physical disk Offline on the host. You can do this by opening the Disk Management MMC snap-in, selecting the disk, and then right-clicking it and selecting Offline. Take care that you don’t bring the same volume online while the VM has it mounted, or you may lose data.

Network Adap ter
You have several items to choose in the Network Adapter Settings window, and you can change the same settings regardless of the type of network adapter—normal or legacy.

• Network. Each network adapter defined in the Settings dialog can be connected to a single virtual network.

• MAC Address. The Media Access Control (MAC) address of a network adapter is what makes each network adapter unique.

Hyper-V gives you the ability to assign a static MAC address to each network adapter in the VM or to use a dynamically generated MAC address. Some applications use the MAC address of a system for a number of purposes. To set a static MAC address, click the Static radio button and enter the value.

Dynamic MAC addresses under Hyper-V always start with 00:15:5D, with the last three octets randomly chosen based on the MAC address of the host’s physical adapter.

• Enable Virtual LAN Identification. If the VM needs to communicate over a specific virtual local area network (VLAN) using the 802.1q protocol, enter the VLAN ID here. Multiple virtual network adapters can be connected to different VLANs.

COM Port
The COM ports in the VM can either be left unconnected (the default selection) or be connected to a named pipe. Named pipes are a special way of communicating between two different systems.

To connect a virtual COM port to a named pipe on the local system, enter the name of the pipe in the Pipe Name text box. There’s no need to format it in the traditional \\.\pipe\pipe syntax; the dialog box takes care of that. To connect to a remote pipe on another system, select the Remote Computer check box and enter the name of the computer.

A VM has a single virtual floppy disk drive. The virtual floppy drive has no access to the physical floppy disk drive—rather, it uses virtual floppy disks (VFD files). You can create VFD files by using the Virtual Disk Wizard (New -> Floppy Disk).

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Managing Windows Server Core

Windows Server Core can be managed a number of different ways:

Local command prompt. Many of the command-line utilities present in a full installation of Windows Server 2008 also exist in a Core installation. This allows administrators to perform the same tasks using a common toolset.

Terminal Server. Windows Server Core supports Terminal Services Remote Administration mode. Administrators can connect to the Server Core system from another Windows system for administrative purposes. The user experience is identical—the user logging in from the remote system will only get a command prompt in their Remote Desktop session.

Terminal Services Remote Administration is disabled by default, just as it is on a full installation of Windows Server 2008.

WS-Management. Web Services for Management (WS-Management) is a relatively newly defined standard in the IT world. It provides a common method for systems to access and exchange management information across the entire IT infrastructure. Many management tools, including System Center Virtual Machine Manager, use WS-Management to communicate between the client and the server.

Windows Remote Shell. By adding this feature, administrators can execute commands on a Server Core system from another system via the command line. Windows Remote Shell uses WS-Management to pass the commands from one system to another.

From the Windows Server Core system, run the following command:

WinRM quickconfig

Now, from a separate Windows Server 2008 or Windows Vista system, you can execute commands against the Windows Server Core system like this:

Winrs -r: dir

This generates a directory listing of the remote Windows Server Core system.

Windows Script Host. Windows Server Core includes the cscript.exe application, allowing you to run scripts for administrative purposes. You can write scripts in a variety of different languages—Jscript, VBScript, and so on (providing the scripting engine for that language is installed).

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Windows Server Core Architecture

The architecture of Windows Server Core is extremely similar to a full installation of Windows Server 2008. Windows Server Core uses the same device drivers, has the same kernel installed on disk, and behaves the same as a full installation of Windows Server. The main difference is that the graphical subsystem of Windows, as well as the .NET Framework and other products nd services, are absent from a Core installation. This means that any application that relies on any of those pieces of functionality won’t run, such as websites that rely on the ASP.NET framework. Some applications, such as SQL Server 2008, also won’t work on a Windows Server 2008 Core installation. Additionally, items such as Internet Explorer and Windows Mail have been removed.

Windows Server Core offers a number of benefits, regardless of its intended use:

Reduced maintenance. By default, a Windows Server Core system has very few binaries installed. When a role is added, only the components that are necessary for the role are installed. The binaries are still present on the system, which allows for those components to be updated during normal patch cycles. No longer will your Windows Servers need updates for little-used components. Systems running Windows Server Core can see up to 40 percent fewer patches compared to systems running Windows Server 2003.

Reduced attack surface. Because fewer applications and services are running on the server, there are fewer avenues to exploit. Exploits aimed at components that don’t exist on the server don’t get a chance to work.

Reduced management. Because fewer components are installed on the system, there’s less administrative overhead.

Less disk space required. Fewer binaries being installed on disk mean that less disk space is required. Windows Server Core requires only 10GB of disk space, as opposed to 20GB for a full installation of Windows Server 2008.

Although the Server Core installation option sounds great in theory, administrators need to be aware of the following concerns:

Remote management. Because Windows Server Core provides no local GUI-based administration tools, you perform the bulk of administration for the system from another system with a full installation of Windows Server 2008 or enterprise-management tools. Many of the Windows administration tools that are accessed through the Microsoft Management Console (MMC) can be configured to administer other computers in either a workgroup or a domain setting.

Command line. The only interface presented at a console or remote logon at a Windows Server Core system is the command line. For some administrators, that’s preferred—and those administrators probably use batch files (.BAT) and command scripts (.CMD) to perform mundane administration tasks. Not all administrators prefer that approach, however.

No PowerShell. Because Windows Server Core doesn’t include the .NET Framework, the PowerShell feature isn’t available. You can still use PowerShell from another system to perform administrative tasks against the Windows Server Core system via Windows Management Interface (WMI).

Inability to transition from Core to full. A Windows Server Core installation can’t be “upgraded” to a full installation of Windows Server. To move to a full installation of Windows Server 2008, you must reinstall the system.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Hyper-V Software Requirements

Hyper-V is a feature of Windows Server 2008 x64 Edition only. There’s no support for Hyper-V in the x86 (aka 32-bit) Edition or the Itanium versions of Windows Server 2008. The x64 Edition is required for a couple of reasons:

Kernel address space The 64-bit version of Windows Server 2008 provides a much larger kernel address space as compared to the 32-bit edition. This directly translates into the support of larger processes, which is crucial for virtualization.

Large amount of host memory Hyper-V supports up to 1 TB of RAM on the host. x86 versions of Windows Server 2008 support only up to 64 GB of RAM on the host, which would severely limit the number of VMs you could run.

We’re frequently asked to explain the differences with Hyper-V between versions of Windows Server 2008. There’s no difference—the features of Hyper-V are the same, regardless of whether you’re running the Standard, Enterprise, or Datacenter product. However, differences in the versions of Windows Server 2008 affect key virtualization scenarios:

Processor sockets Windows Server 2008 Standard Edition is limited to four sockets, whereas Enterprise Edition supports eight sockets.

Memory Windows Server 2008 Standard Edition supports up to 32 GB of RAM, and
Windows Server 2008 Enterprise Edition supports up to 2 TB of RAM. Failover clustering Windows Server 2008 Standard Edition doesn’t include the failover clustering functionality required for quick migration.

Windows Server 2008 includes the rights to run virtual images of the installed operating system. The number of those virtual images is tied to the edition.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Hyper-V Requirements

Because Hyper-V is included as a role of Windows Server 2008 x64 Edition, it inherits the same hardware requirements. However, a few areas require special attention for Hyper-V.

Hardware Requirements
Some of the requirements for Hyper-V are hard requirements, such as the type of processor, whereas others are best practices to ensure that Hyper-V performs optimally.

Hyper-V requires a 64-bit capable processor with two separate extensions: hardware-assisted virtualization and data-execution prevention. Hardware-assisted virtualization is given a different name by each vendor—Intel calls it Virtualization Technology (VT), and AMD calls it AMD Virtualization (AMD-V). Almost all processors now ship with those features present, but check with your processor manufacturer to make sure. Although the functionality is required in the processor, it’s also required to be enabled in the BIOS. Each system manufacturer has a different way of exposing the functionality, as well as a different name for it. However, most, if not all, manufacturers provide a way to enable or disable it in the BIOS. You can enable it in the BIOS, but some systems don’t enable the feature unless there’s a hard-power cycle—shutting off the system completely, for example. We recommend that the system be completely powered off.

Data-execution prevention (DEP) goes by different names depending on the processor manufacturer—on the Intel platform, it’s called eXecute Disable (XD); and AMD refers to it as No eXecute (NX). DEP helps protect your system against malware and improperly written programs by monitoring memory reads and writes to ensure that memory pages marked as Data aren’t executed. Because you’ll be running multiple VMs on a single system, ensuring stability of the hosting system is crucial.

As we talked about earlier, Hyper-V’s architecture lets you use standard Windows device drivers in conjunction with the VSP/VSC architecture. As such, any of the storage devices listed in the Windows Server Catalog will work with Hyper-V. These include SCSI, SAS, fibre channel, and iSCSI—if there’s a driver for it, Hyper-V can use it. Of course, you’ll want to take some considerations into account when planning the ideal Hyper-V host.

Here are some of the areas where extra attention is necessary:

Multiple spindles and I/O paths. Most disk-intensive workloads, such as database servers, need multiple spindles to achieve high performance. Hyper-V’s storage architecture enables those workloads to be virtualized without the traditional performance penalty. When multiple disk-intensive workloads share the same disk infrastructure, they can quickly slow to a crawl. Having multiple disks (as well as multiple I/O paths) is highly recommended for disk-intensive workloads. Even two workloads sharing a host bus adapter with a single fibre channel can saturate the controller, leading to decreased performance. Having multiple controllers also can provide redundancy for critical workloads.

Disk configurations for optimal performance Hyper-V has a number of different ways to store the VM’s data, each with its own pros and cons:

Pass-through disks:
• Pros: Pass-through disks generally provide the highest performance. The VM writes directly to the disk volume without any intermediate layer, so you can see near-native levels of performance.
• Cons: Maintaining the storage volumes for each VM can be extremely challenging, especially for large enterprise deployments.

virtual hard disks:
• Pros: These are the best choice for production environments using VHD files. Because you allocate all the disk space when you create the VHD file, you don’t see the expansion penalty that occurs with the dynamically expanding VHD.
• Cons: Because all the space for the VHD is allocated at creation, the VHD file can be large.

Dynamic virtual hard disks:
• Pros: A dynamically expanding VHD expands on demand, saving space on the system until it’s needed. Disks can remain small.
• Cons: There is a small performance penalty when a disk is expanded. If large amounts of data are being written, the disk will need to be expanded multiple times.

Snapshots. Snapshots are extremely useful in the test and development environment. However, what can be helpful in one environment can be harmful in another. You shouldn’t use snapshots in a production environment because rolling back to a previous state without taking the proper precautions can mean data loss!

Much like storage, networking with Hyper-V inherits the rich driver support of Windows Server 2008. Many of the caveats for storage apply to networking as well—ensure that multiple NICs are present so a single interface doesn’t become the bottleneck.

The following list identifies areas where you should pay special attention with networking:
• Hyper-V supports Ethernet network adapters, including 10, 100, 1000, and even 10GbE network adapters. Hyper-V can’t use ATM or Token Ring adapters, nor can it use wireless (802.11) adapters to provide network access to the VMs.

• During the Hyper-V role installation you can create a virtual network for each network adapter in your system.

• We recommend that you set aside a single NIC to manage the host. That NIC shouldn’t be used for any VMs (no virtual switch should be associated with it). Alternatively, you can use out-of-band management tools to manage the host. Such tools typically use an onboard management port to provide an interface to the system.

Software Requirements
Hyper-V is a feature of Windows Server 2008 x64 Edition only. There’s no support for Hyper-V in the x86 (aka 32-bit) Edition or the Itanium versions of Windows Server 2008. The x64 Edition is required for a couple of reasons:

Kernel address space The 64-bit version of Windows Server 2008 provides a much larger kernel address space as compared to the 32-bit edition. This directly translates into the support of larger processes, which is crucial for virtualization.

Large amount of host memory Hyper-V supports up to 1 TB of RAM on the host. x86 versions of Windows Server 2008 support only up to 64 GB of RAM on the host, which would severely limit the number of VMs you could run.

We’re frequently asked to explain the differences with Hyper-V between versions of Windows Server 2008. There’s no difference—the features of Hyper-V are the same, regardless of whether you’re running the Standard, Enterprise, or Datacenter product. However, differences in the versions of Windows Server 2008 affect key virtualization scenarios:

Processor sockets. Windows Server 2008 Standard Edition is limited to four sockets, whereas Enterprise Edition supports eight sockets.

Memory. Windows Server 2008 Standard Edition supports up to 32 GB of RAM, and Windows Server 2008 Enterprise Edition supports up to 2 TB of RAM.

Failover clustering. Windows Server 2008 Standard Edition doesn’t include the failoverclustering functionality required for quick migration.

Virtual image use rights. Windows Server 2008 includes the rights to run virtual images of the installed operating system. The number of those virtual images is tied to the edition.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Hyper-V Features

Now that we’ve gone over both the scenarios and architecture of Hyper-V, let’s dive into some of the features of Microsoft’s virtualization platform:

32-bit (x86) and 64-bit (x64) VMs Hyper-V provides support for both 32-bit as well as 64-bit VMs. This lets users provision both architectures on the same platform, easing the transition to 64-bit and providing legacy 32-bit operating systems.

Large memory support (64 GB) within VMs With support for up to 64 GB of RAM, Hyper-V scales out to run the vast majority of enterprise-class workloads. Hyper-V can also use up to a total of 1 terabyte (TB) of RAM on the host.

SMP virtual machines Symmetric Multi Processor (SMP) support allows VMs to recognize and utilize four virtual processors. As a result, server applications running in a Hyper-V VM take full advantage of the host system’s processing power.

Integrated cluster support for quick migration and high availability (HA) Windows Server 2008 Hyper-V and HA go hand in hand. It’s easy to create a failover cluster of VM hosts that your VMs can live on. After you set up the failover cluster, you can quickly and easily move a VM from one host to the other from the Failover Cluster Manager or from other management tools (such as System Center Virtual Machine Manager).

Volume Shadow Service integration for data protection Hyper-V includes a Volume Shadow Services (VSS) provider. As we discussed earlier, in the list of scenarios, VSS lets backup applications prepare the system for a backup without requiring the applications (or VMs) to be shut down.

Pass-through high-performance disk access for VMs When a physical volume is connected directly to the VM, disk I/O–intensive workloads can perform at their peak. If the Windows Server 2008 system can see the volume in the Disk Management control panel, the volume can be passed through to the VM. Although you’ll see faster performance with pass-through disk access, certain features (such as snapshots, differencing disks, and host-side backup) that you get from using a VHD file aren’t available with pass-through disks.

VM snapshots Snapshots let administrators capture a point in time for the VM (including state, data, and configuration). You can then roll back to that snapshot at a later point in time or split from that snapshot to go down a different path. The snapshot is a key feature for the test and development scenario, because it lets users easily maintain separate points in time. For example, a user may install an operating system inside a VM and take a snapshot. The user can perform a number of tasks and then take a second snapshot. Then, the user can return to either of those snapshots later, saving configuration time and effort.

New hardware-sharing architecture (VSP/VSC/VMBus) By using the new VMBus communication protocol for all virtual devices, Hyper-V can provide higher levels of performance than were previously seen with Microsoft virtualization products.

Robust networking: VLANs and NLB Virtual Local Area Network (VLAN) tagging—also referred to as the IEEE standard 802.1q—provides a secure method for multiple networks to use the same physical media. Hyper-V supports VLAN tagging (802.1q) on the virtual network interfaces and specifies a VLAN tag for the network interface. Network Load Balancing (NLB) support in Hyper-V allows VMs to participate in an NLB cluster. An NLB cluster is different from a failover cluster, such as those used for VM quick migration. NLB clusters are configured with front-end nodes that handle all incoming traffic and route it to multiple servers on the back-end.

DMTF standard for WMI management interface The Distributed Management Task Force (DMTF) is a standards body that provides a uniform set of standards for the management of IT environments. Microsoft has worked closely with the DMTF to ensure that all the management interfaces for Hyper-V adhere to the standards, allowing management tools from multiple vendors to manage the system.

Support for full or Server Core installations Hyper-V can run on a full installation of Windows Server 2008 as well as the Server Core option. We’ll discuss Server Core in more depth later.

Advantages over Virtual Server
Windows Server 2008 Hyper-V has a number of advantages over Virtual Server 2005 R2 SP1:

• Support for SMP and 64-bit VMs. Virtual Server was limited to 32-bit uni-processor virtual machines.
• Support for more than 3.6 GB of RAM per VM.
• Support for mapping a logical unit number (LUN) directly to a VM.
• Increased performance from VSP/VSC architecture.
• Hyper-V management via a MMC-based interface instead of the web-based console.

However, it’s impossible for users who have only 32-bit hardware in their environment to move to Hyper-V (because it’s a feature of the 64-bit version of Windows Server 2008).

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Hyper-V Architecture - Virtual Machine

A VM can have two different types of devices: emulated and synthetic. Although synthetic devices are encouraged due to their superior performance, they aren’t available for all operating systems. Emulated devices are present in Hyper-V mainly for backward compatibility with nonsupported operating systems. VMs running certain distributions of Linux have synthetic device support as well. Let’s examine each type of device.

Emulated Devices
Emulated devices in Hyper-V exist primarily for backward compatibility with older operating systems. In an ideal world, all applications would run on the latest version of the operating system they were designed for, but that’s far from reality. Many companies have systems in production that run on older copies of operating systems because one of their applications doesn’t run on anything newer. An older operating system may not be supported under Hyper-V, which means it can’t take advantage of the high-performance I/O. That’s not a total loss, however: If you consolidate those older systems onto a newer Hyper-V host, the advantages of moving to a more up-to-date hardware platform can provide a performance boost.

Emulated devices have another key role. During the installation of the VM, operating systems don’t have support for the synthetic devices that may be installed in the VM. For that reason, you must use emulated devices—otherwise, the operating-system installation can’t function. For Hyper-V, it’s easy to move from emulated to synthetic devices.

The emulated devices presented to a VM are chosen for their high degree of compatibility
across a wide range of operating systems and in-box driver support. The video card is based on an S3 video card, and the network card is an Intel 21140-based Ethernet adapter.

Emulated devices under Hyper-V don’t perform as well as the new synthetic devices. Thanks to part of the work that was done to harden the entire virtualization stack, emulated devices execute in the worker process—specifically, in user mode in the parent partition.

How does I/O happen with emulated devices?

The below are about how emulated storage requests are handled. Emulated networking is handled in a similar fashion. I want to point out a few specific items:

• Context switches are used. A context switch is a switch from executing a particular processor instruction in kernel mode to user mode. When paired with virtualization, a context switch is an “expensive” operation. There’s no money involved, but the CPU cost for such an operation is very high. That time could be spent doing other tasks.

• The path that the data packet traverses is long, especially compared to the synthetic case (which we’ll review next).

• The path illustrated in the figure is repeated hundreds of times for a 10 kilobyte write to disk. Imagine if you’re doing a large SQL transaction that involved writing hundreds of megabytes to disk, or running a popular website being served up from IIS running in the VM. You can see that it won’t scale well.

Synthetic Device Drivers
Synthetic devices provide much higher performance than their emulated counterparts. By taking advantage of VMBus, synthetic devices can execute I/O transactions at a much faster rate. Synthetic devices, such as the Microsoft Virtual Machine Bus Network Adapter, don’t have real-world counterparts. They are purely virtual devices that function only with Hyper-V—loading the drivers on a physical system does nothing. These new synthetic devices rely on VMBus.

Synthetic device drivers are available only for operating systems that are supported by Microsoft. (For reference, a list of supported operating systems for Hyper-V is available at If you’re running an operating system in the VM that isn’t supported by Microsoft, you’ll need to use the emulated devices in the VM. Much like the emulated storage request chart presents a lot of data. Here are a few key differences:

• In the beginning, the data path is similar to the emulated data path. •u However, the synthetic storage device in Hyper-V is a SCSI-based device—so the last driver it hits before getting put on VMBus is the StorPort driver.

• When a packet makes it to the miniport driver, it’s put on VMBus for transport to the Storage VSP in the parent partition. Because VMBus is a kernel-mode driver, no context switches are necessary.

• After the data packet crosses over to the parent partition, the correct destination is determined by the VSP, which routes the packet to the correct device. The destination is a virtual hard disk (VHD) file.

Installing Synthetic Device Drivers
It’s easy to install synthetic device drivers in the VM. After you’ve installed the operating system, select Action -> Insert Integration Services Setup Disk. An installer launches and automatically installs the drivers for you. When you reboot, the VM can take advantage of the new architecture.

A special synthetic driver deals with the boot process: Optimized Note Boot Performance.
Because the synthetic drivers rely on VMBus, you can’t boot off hard drives that are connected to the SCSI controller. All isn’t lost—during the boot process, after the VMBus driver is loaded, all the IDE boot traffic is automatically routed through the same infrastructure that is used for SCSI traffic. This means the boot process and all disk traffic (reads and writes) perform at the same accelerated speed.

Linux Device Drivers
No, that’s not a typo—certain distributions of Linux are supported under Hyper-V. Not only is the operating system supported, but a full set of device drivers also enable synthetic device support under Linux. The drivers include the Hypercall adapter—a thin piece of software that runs in the Linux VM and increases performance by translating certain instructions to a format that Hyper-V can understand.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Hyper-V Architecture - Parent Partition

The installation of Windows is now running on top of the Windows hypervisor. One of the side effects of running on top of the hypervisor is that the installation is technically a VM. We’ll refer to this as the parent partition. The parent partition has two special features:

• It contains all the hardware device drivers, as well as supporting files, for the other VMs.

• It has direct access to all the hardware in the system. In conjunction with the virtualization service providers, the parent partition executes I/O requests on behalf of the VM—sending disk traffic out over a fibre channel controller, for example.

The following best practices provide a secure and stable parent partition, which is critical to the VMs running on the host:

• Don’t run any other applications or services in the parent partition. This may seem like basic knowledge for system administrators, but it’s especially crucial when you’re running multiple VMs. In addition to possibly decreasing stability, running multiple roles, features, or applications in the parent partition limits the amount of resources that can otherwise be allocated to VMs.

• Use Windows Server 2008 in the Core role as the parent partition.

Windows Hypervisor
The Windows hypervisor is the basis for Hyper-V. At its heart, the hypervisor has only a few simple tasks: creating and tearing down partitions. (A partition is also known as the basis for a VM) and ensuring strong separation between the partitions. It doesn’t sound like much, but the hypervisor is one of the most critical portions of Hyper-V. That’s why development of the hypervisor followed the Microsoft Security Design Lifecycle process so closely—if the hypervisor is compromised, the entire system can be taken over, because the hypervisor runs in the most privileged mode offered by the x86 architecture. One of Microsoft’s design goals was to make the Microsoft hypervisor as small as possible. Doing so offered two advantages:

• The Trusted Computing Base (TCB) is smaller. The TCB is the sum of all the parts of the system that are critical to security. Ensuring that the hypervisor is small reduces its potential attack vectors.

• The hypervisor imparts less overhead on the system. Because all VMs (as well as the parent partition) are running on top of the hypervisor, performance becomes a concern. The goal is to minimize the hypervisor’s overhead.

Kernel-Mode Drivers
A Windows kernel-mode driver is one of two types of drivers in Windows. Kernel-mode drivers execute in Ring 0. Because this type of driver is executing in kernel mode, it’s crucial that these drivers be as secure as possible: An insecure driver, or a crash in the driver, can compromise the entire system.
Hyper-V adds two kernel-mode drivers:

VMBus. VMBus is a high-speed in-memory bus that was developed for Hyper-V. VMBus acts as the bus for all I/O traffic that takes place between the VMs and the parent partition. VMBus works closely with the virtualization service provider and virtualization service client.

Virtualization Service Provider (VSP). The Virtualization Service Provider (VSP) enables VMs to securely share the underlying physical hardware by initiating I/O on behalf of all VMs running on the system. It works in conjunction with the hardware vendor drivers in the parent partition—which means that no special “virtualization” drivers are necessary. If a driver is certified for Windows Server 2008, it should work as expected with Hyper-V. Each class of device has a VSP present—for example, a default installation of Hyper-V has a networking VSP as well as a storage VSP. The VSPs communicate with the matching Virtualization Service Client (VSC) that runs in the VM over VMBus. We’ll cover the VSC when we look at the different types of VMs.

User-Mode Applications
User-mode applications are, strangely enough, applications that run in user mode. They execute in Ring 3, which is where all unprivileged instructions are run. Many of the applications that run in Windows are user-mode applications—for example, the copy of Notepad that you use to look at a text file is executing in user mode.
Hyper-V has a number of different user-mode applications:

Virtual Machine Management Service (VMMS). The VMMS acts as the single point of
interaction for all incoming management requests. It interacts with a number of processes,
two of which we’ll refer to here.

WMI providers. Hyper-V has a rich set of WMI interfaces. They provide a way to manage the state and health of the VMs as well as get settings information and some performance information. All the WMI interfaces are fully documented on

Worker processes. When a VM is started up, a worker process is created. The worker process represents the actions that are taking place in the virtual processor, as well as all emulated devices and the virtual motherboard. Each VM that is running on a host has a worker process.

Now that we’ve shown you what’s happening in the parent partition, let’s look at the VMs. After you create a VM and power it on, you can install a wide variety of x86/x64-based operating systems. Even though these are VMs, they can run the same operating systems without modification as a physical computer. But operating systems that are supported by Microsoft include new synthetic drivers, which work in conjunction with the matching VSP running in the parent partition.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Scenarios for Hyper-V

Hyper-V was developed with a several key scenarios in mind. When Microsoft started developing Hyper-V, the development team spent a great deal of time meeting with customers who were using virtualization—small businesses, consultants who implement virtualization on behalf of their customers, and large companies with multimillion dollar IT budgets. The following key scenarios were developed as a result of those meetings; they represent customer needs, demands, and wants.

Server Consolidation
Systems are becoming increasingly powerful. A couple of years ago, it was rare to find a quadprocessor server at a price most customers could afford. Now, with major processor manufacturers providing multicore functionality, servers have more and more processing power. Multicore technology combines multiple processor cores onto a single die—enabling a single physical processor to run multiple threads of execution on separate cores. Virtualization and multicore technology work great together: If you’re combining multiple workloads onto a single server, you need to have as much processing power as possible. Multicore processors help provide the optimal platform for virtualization.

Businesses are increasingly likely to need multiple systems for a particular workload. Some workloads are incredibly complex, requiring multiple systems but not necessarily using all the power of the hardware. By taking advantage of virtualization, system administrators can provide a virtualized solution that better utilizes the host hardware—thus allowing administrators to get more out of their expenditure.

Workloads aren’t the only driving item behind virtualization. The power and cooling requirements of modern servers are also key driving factors. A fully loaded rack of servers can put out a significant amount of heat. (If you’ve ever stood behind one, you’re sure to agree—it’s a great place to warm up if you’ve been working in a cold server room.) All that heat has to come from somewhere. The rack requires significant power.

But for companies in high-rise buildings in the middle of major cities, getting additional power is incredibly difficult, if not impossible. In many cases, the buildings weren’t designed to have that much power coming in—and the companies can’t add more power without extensive retrofitting. By deploying virtualization, more workloads can be run on the same number of servers.

Testing and Development
For people working in a test or development role, virtualization is a key to being more productive. The ability to have a number of different virtual machines (VMs), each with its own operating system that’s ready to go at the click of a mouse, is a huge time-saver. Simply start up whichever VM has the operating system. You no longer need to install a clean operating system. Also, by using the snapshot functionality, users can quickly move between known states in the VM.

With Hyper-V’s rich Windows Management Interface (WMI) interfaces, testing can be started automatically. By scripting both Hyper-V and the operating system to be tested, testers can run a script that starts the VM, installs the latest build, and performs the necessary tests against it. A Hyper-V virtual machine is also portable. A tester can work in the VM; if an issue is found, the tester can save the state of the VM (including the memory contents and processor state) and transfer it to the developer, who can restore the state at their convenience. Because the state of the VM is saved, the developer sees exactly what the tester saw.

Business Continuity and Disaster Recovery
Business continuity is the ability to keep mission-critical infrastructure up and running. Hyper-V provides two important features that enable business continuity: live backup and quick migration. Live backup uses Microsoft Volume Shadow Services functionality to make a backup of the entire system without incurring any downtime, as well as provide a backup of the VM at a known good point in time. The system backup includes the state of all the running VMs. When a backup request comes from the host, Hyper-V is notified, and all the VMs running on that host are placed into a state where they can be backed up without affecting current activity; they can then be restored at a later time.

Quick migration is the ability to move a VM from one host to another in a cluster using Microsoft Failover Cluster functionality. During a quick migration, you save the state of the VM, move storage connectivity from the source host to the target host, and then restore the state of the VM. Windows Server 2008 added support for the virtual-machine resource type to the Failover Clustering tool, enabling you to make a VM highly available using functionality included with the operating system.

Disaster recovery is becoming a requirement for increasing numbers of businesses. With natural disasters such as Hurricane Katrina fresh in the minds of system administrators, enterprises are seeking ways to keep their businesses running throughout such events. You must consider more than just big disasters, though—small disasters or even simple configuration issues can lead to a mission-critical service being unavailable. Hyper-V includes support for geographically dispersed clusters (a new feature of Windows Server 2008).

Dynamic IT
Microsoft’s idea of a dynamic IT infrastructure involves self-managing dynamic systems— systems that adjust automatically to the workload they’re running. By using Hyper-V in conjunction with the systems-management functionality present in the System Center family of products, enterprises can take advantage of the benefits of virtualization to meet the demands of a rapidly changing environment. Now that we’ve covered Hyper-V’s key targeted scenarios, let’s review the architecture of Hyper-V to see how Microsoft has implemented support for them.

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Microsoft’s Approach to Virtualization

Some software companies address virtualization from a single direction. VMware, for example, focuses on virtualizing and managing operating-system instances. Microsoft has been more thoughtful and less myopic in its approach. Microsoft’s articulated virtualization direction is in five key areas:

• Server—Hyper-V and Virtual Server 2005 for server services
• Desktop—Virtual PC for client-centric, local operating-system instances
• Presentation—Terminal Services providing remote desktop and application access
• Application—SoftGrid/AppV for application encapsulation
• Profile—Roaming profiles for personal-experience encapsulation

All these approaches are tied together by Windows as a platform and managed by the System Center family of products to enable administration of virtual and physical resources. You can benefit from this multipronged approach to virtualization, which is unified by a common platform and management suite.

It’s All Windows
The great thing about virtualization technology from Microsoft is that it’s integrated with Windows. Windows is a platform well known to administrators and users alike. You don’t need special training to use Microsoft’s virtualization offerings because they’re already familiar. You don’t need to be a virtualization specialist to use Hyper-V, Terminal Services, or AppV (as you might with VMware). You can have virtualization as a competency, just as you might with other focus areas of Windows administration.

System Center Manages All Worlds Well
You manage and monitor each of these virtualization offerings with the same System Center tools that you may already have in your environment for physical system management. Some virtualization-management tools only provide insight into the virtualization layer and can’t dive further into running operating systems or applications (they’re essentially half blind). Using a unified, familiar tool set that can correlate data between physical, virtual, and application software can magnify the benefits of virtualization.

Mixing and Matching with Virtualization
You can use these separate directions of virtualization together with the others to provide more value. You can combine the different focuses of virtualization—server, desktop, presentation, application, and profile—to meet the needs and requirements of changing enterprises. Why not rapidly provision Hyper-V–based virtual machines for thin-client access to meet dynamic demands? How about combining AppV with Terminal Services to alleviate application coexistence issues and reduce server count?

Source of Information : Sybex Windows Server 2008 Hyper-V Insiders Guide to Microsofts Hypervisor

Working with Windows XP Mode

Windows Virtual PC utilizes a number of “Integration Components” to make it easy for you to access many of the same resources from within the Windows XP virtual environment as those that are used by your Windows 7-based PC.
This integration enables the two environments to share such things as network connections, clipboard content, printers, USB devices, Smart Cards, and external storage.

• Accessing Your Windows 7-based PC’s Network Connections
When working in Windows XP Mode, you can use the network connections of your Windows 7-based PC to access the Internet from your virtual machine. This means that many of your older Windows XP applications can access the Internet as needed, without any additional effort on your part.

If your company has a corporate network, you can domain-join the virtual machine to that network just as you would the physical machine.

• Sharing Files and Folders Between Environments
Because the Clipboard is shared between physical and virtual machines, you can copy and paste any data you want between Windows XP applications and their counterparts in Windows 7.

Although drag-and-drop operations are not permitted between the physical and virtual machines, you can access your physical machine’s hard drive from the virtual machine. In addition, the physical machine’s My Documents folder will appear on your Virtual
Windows XP desktop as well, for easy access to any files you may require.

• Accessing External USB Devices — Desktop Mode
Windows XP Mode for Windows 7 supports the use of external USB devices that are attached to your Windows 7-based PC. USB storage devices, scanners, and Smart Cards whose drivers are installed on the Windows 7 host and the virtual machine are automatically shared with the virtual machine if the integration features are enabled. You can also easily access the host CD drive, and print on a local or network printer from within your Windows XP applications.

If an attached USB device does not appear in the My Computer window, you will need to make it available to the virtual machine. This is done by going to the USB drop-down menu that appears either in the upper-left hand corner of the Windows XP desktop window (Desktop Mode), or at the top of the desktop (Full-Screen Desktop Mode). Click on the device’s name to capture it for use by the virtual machine.

To release the device for use once again by the physical machine, click on the device name once more in the drop-down USB menu. It is now ready for safe removal from the host PC.

• Accessing External USB Devices — Seamless Mode
When working with a Windows XP applications in Seamless Mode (that is, launched directly from the Windows 7 Start Menu, desktop, or Taskbar), you can access external USB devices through the application’s regular File Menu commands, such as Open and Save As.

If a USB device is not compatible with Windows 7, you can still use it in Seamless Mode. To do this, simply attach the device in Desktop Mode, as specified in the section above. Then when you run your application in Seamless Mode, you will have access to the device.

Source of Information : Microsoft® Enterprise Desktop Virtualization (MED-V)

Using Windows XP Applications in the Virtual Environment

Windows XP Mode for Windows 7 makes it possible for you to use many of your older Windows XP applications right on your Windows 7-based PC. As you’ll see, installing and running those applications is accomplished exactly as you would in the Windows XP operating system that you’ve become so familiar with.

• Installing Windows XP applications
Install your Windows XP applications exactly as you would on a Windows XP-based PC. Click on the “My Computer” window from your Windows XP Start Menu to access the CD/DVD, internal hard drive, or external device on which your application resides. Double-click on the file to be installed and follow the prompts. (Note: in order to publish your applications to the Windows 7 desktop, they must be installed for all users.)

You can create a desktop shortcut for your application on the Windows XP desktop, the Windows 7 desktop, or both. You can also pin the application to your Windows XP Start Menu, and, for added convenience, to the Windows 7 Start Menu as well.

• Running Windows XP applications in Desktop Mode
Once you’ve installed your Windows XP application, it can be launched from your Windows XP “All Programs” list or Start Menu. Create a desktop shortcut to launch the app from the Windows XP desktop whenever you’re operating in Desktop Mode (i.e., from within the Windows XP environment).

You can close application windows or minimize them to the Windows XP Taskbar as desired.

• Running Windows XP applications in Seamless Mode
Windows XP Mode for Windows 7 enables you to run your Windows XP applications directly from the Windows 7 desktop in what is called “Seamless Mode.” This means that once you’ve installed an application, it will also appear in your Windows 7 All Programs menu, along with all of your other Windows 7 applications.

Because of this, you don’t have to open the Virtual Windows XP desktop environment in order to run these applications. Simply launch them directly from the Windows 7 Start Menu (or from the Windows 7 desktop, if you have already created a desktop shortcut there for the application). Launching this application means also launching the virtual machine, so it may take a moment or two for the application to complete this process.

After it is launched, the application will perform exactly like any other application on the Windows 7 desktop: you can minimize it to the Windows 7 Taskbar for future use, or close it if you prefer.

• Hibernation vs. Log-Off
When you are through working with the Windows XP environment (Desktop Mode), you can put it into “hibernation” simply by clicking on the Close button in the upper right corner. It takes only a few seconds to complete this process.

If it’s the first time you’ve run a Windows XP application in Desktop mode, you may be asked to log-off before the Windows XP virtual machine completes the hibernation process. Once you’ve logged on again, you can continue to work in regular Windows 7 mode, Windows XP Seamless Mode, or Windows XP Desktop Mode whenever you like.

Source of Information : Microsoft® Enterprise Desktop Virtualization (MED-V)

Getting Started with Windows XP Mode

Setting up your Windows 7-based PC to run in Windows XP Mode is a simple and straightforward process.

The first thing you’ll want to do is to check All Programs in your Start Menu to see whether Windows Virtual PC is already set up on your machine.

• If you don’t already have Windows Virtual PC installed:
The first step is setup your PC environment for virtualization. Windows Virtual PC takes advantage of hardware virtualization technology. To run Windows Virtual PC, your PC has to have Intel® VT or AMD-V™ features enabled in the BIOS. To find out if your PC is virtualization capable, visit the Windows Virtual PC support page (link: or your manufacturer’s website for moredetails.

With the hardware virtualization feature enabled, if Windows Virtual PC does not appear in All Programs, you’ll need to download it, as well as Virtual Windows XP, from the following website:

Once you’ve downloaded these files, double click “Windows6.1‐KB958559‐x86.msu (or x64-based on your system architecture).” Once it has finished installing, shut down your PC fully and then restart. Once restarted, your PC’s Start Menu will include Windows Virtual PC.

• If you already have Windows Virtual PC (or have just downloaded and installed it):
The next step is to install Windows Virtual XP on a virtual machine.

• Installing Virtual Windows XP:

If you have not already downloaded Virtual Windows XP from the above link, do so now. Double click “VirtualWindowsXP.msi.”

When installation is complete, go to All Programs and click on Virtual Windows XP to begin the set-up of your virtual Windows XP environment. The set-up process for Virtual Windows XP will take several minutes. During this time you be asked to accept the Windows XP License Agreement, as well as to create a new password and whether or not to receive Automatic Updates.

Once the process is complete, you will see your new Virtual Windows XP environment as a window on your Windows 7 desktop.

An important consideration of working with virtualization technology is the fact that the user has both the physical and virtual PC to maintain. Every PC requires a degree of maintenance including but not limited to keeping the operating system and applications up to date with patches, virus and malware protection, and backup. Windows XP Mode is pre-configured with the Windows XP firewall and to apply updates automatically from Windows Update. It is not pre-configured with anti-virus or anti-malware software, and both types of security software are recommended.

You can install and run applications within this Windows XP environment (known as Desktop Mode) exactly as if you were running them on a Windows XP-based PC. If you like, you can expand the Windows XP desktop to completely fill the screen (Full-Screen Desktop Mode) by clicking on the Maximize button in the upper right corner of the window.

When operating in Full-Screen Desktop Mode, you will notice that there is a small menu bar at the top of the desktop. This will enable you to access certain Virtual PC functions that we’ll talk about later without leaving the Full-Screen mode.

Source of Information : Microsoft® Enterprise Desktop Virtualization (MED-V)

Introduction to Windows XP Mode for Windows 7

Windows® XP Mode, a new feature of Windows 7 Professional, Enterprise and Ultimate, helps small businesses upgrade to Windows 7 by providing a virtual Windows XP environment capable of running many Windows XP-compatible business and productivity applications. Using Windows Virtual PC, a new feature in Windows 7, customers can run many older Windows XP business and productivity applications within Windows XP Mode and launch them from the Windows 7 desktop with just a single click.

Therefore, Windows XP Mode for Windows 7 gives you the best of both worlds: the ability to enjoy the many benefits of Windows 7—such as increased security, productivity, and reliability— while still getting the most from your Windows XP applications.

In this Guide, we’ll tell you about Windows XP Mode and Windows Virtual PC for Windows 7. We’ll show you how easy it is to install and run many of your Windows XP productivity applications just from Windows 7 desktop; and we’ll talk about other new features that make working with virtual machines more convenient than ever.

What’s new in Windows Virtual PC?
With the release of Windows 7, we are introducing a number of new features in Windows Virtual PC designed to make it easier for you to run your legacy applications in a virtual software environment like Virtual Windows XP:

• Integration with Windows XP Mode setup (Windows XP Mode is a feature of Windows 7 Professional, Ultimate and Enterprise)

• A new approach that intuitively incorporates Windows Virtual PC user interface (UI) into that of your Windows 7 desktop

• The ability to use many of your USB devices from within a virtual Windows environment, such as Windows XP Mode

• Seamless launching of Windows XP applications from your Windows 7 desktop, Start Menu, or Taskbar

• Clipboard sharing, which enables you to cut, copy, and paste data between the host
Windows 7 desktop and the virtual machine

• Printer sharing between the Windows 7 desktop and the virtual Windows environment

• Drive sharing, which provides easy access to all host data from within the virtual machine

• Folder integration between operating environments

Source of Information : Microsoft® Enterprise Desktop Virtualization (MED-V)

Windows 7 Internet Explorer 8 Usability

Windows 7 ships with the new Internet Explorer 8 (IE8). IE8 builds on the foundation of IE7 and this latest release contains many useful enhancements in the areas of usability, privacy, and security.

The first major noticeable improvement in IE8 is usability. Microsoft has taken pains to improve the usability of IE8 by adding the following features:
• Smarter Address bar that lists all the relevant sites you have visited by searching through your History, Favorites, and RSS Feeds

• Enhanced functionality of tabbed browsing by color-coding related tabs

• Support for older websites by displaying them using IE7 through the Compatibility

• A much more usable Find feature to make searching for phrases on the web page easy

• Ability to visually search for items from providers like and

• Web Slices to help users monitor constantly changing web content

• Accelerators, which integrate commonly used functions into the browser so that users can perform common actions with a single mouse-click.

Smart Address Bar
The Address bar in IE8 is now much smarter than its predecessor. In addition to typing websites’ URLs, you can now type in keywords and it will search across your History, Favorites, and RSS Feeds and display all matching sites that you have visited previously.

This feature is very useful for finding pages that you have visited previously but whose
URLs you cannot remember.

Enhanced Tabbed Browsing and Grouping
Prior to IE7, IE users were clamoring for tabbed browsing, which was a feature already available in competing browsers like Firefox and Opera. However, with tabbed browsing in IE7, things soon got out of control. You suddenly had tons of tabs on your browser window, and it was quite a task to manage them.

In IE8, when you create a new tab from an existing tab (for example, by right-clicking a link and selecting Open in New Tab), the new tab (and the existing tab) will be colorcoded to help you visually group them together.

When you right-click one of the tabs, you can close the current selected tab, close the entire tab group, or ungroup the current tab from the current group. When you start a new tab, IE8 will provide several options with which you can open previously closed tabs as well as reopen the last browsing session. The “Reopen closed tabs” option allows you to reopen all the tab pages that you have closed during the current browsing session. The Reopen Last Browsing Session option opens all the page(s) that you opened during your previous browsing session (before you closed your IE window).

Compatibility View
IE8 supports Compatibility View, which allows sites not optimized for IE8 to be displayed the way IE7 would have displayed them. This corrects problems such as misaligned text, images, and text boxes. To force a site to be displayed in IE7 mode, click the Compatibility View button located next to the URL of the site.

You also have the option to maintain a list of sites that need to be displayed in compatibility view. To do so, go to the Command bar and select Tools->Compatibility View Settings. You can now add the URL of sites that you want to view in Compatibility View. Observe that in this window, you have several options for viewing pages in Compatibility View. You can obtain updated lists from Microsoft, disable IE8 to display Intranet sites in Compatibility View, or force all pages to be displayed in Compatibility View.

What does it mean for a site to be unoptimized for IE8? Technically, IE8 is more up-to-date with modern web standards than IE7. However, some older sites that were optimized for IE7 relied on idiosyncrasies in how IE7 interpreted modern web standards. So, although IE8 should be more standards-compliant, there are still some websites that relied on IE-specific workarounds that don’t look quite as good under IE8 as they did under IE7.

When viewing intranet pages, IE8 will automatically render the content using IE7 Standards mode. This is done to ensure maximum compatibility, as many intranet apps are still based on IE7. Hence the Compatibility View button will not be shown for Intranet pages.

Find on Page
One of the most frustrating features in IE7 (as well as previous versions) was the Find feature. Anyone who has used this feature knows that you needed to scroll the page to the top before you could start searching for the things you want. For a long time, IE has been playing catchup with browsers like Safari and Firefox, and finally in IE8, the Find feature that most users are waiting for is finally here.

To find a word or phrase on the page, press Ctrl-F (or go to Edit->Find on this Page...) and type the word or phrase you want to search for. Once the word or phrase is found, you will see the result bar.

All occurrences of the word or phrase are highlighted in yellow and the current word is highlighted in blue. To move to the next or previous occurrence of the phrase, click the Previous or the Next button.

Improved Search
Searching in IE8 has now been improved. Microsoft is partnering with various search providers to provide “visual searches.” For example, you can visually search’s huge library of books from within IE. All you need to do is to add the Amazon Search Suggestion search provider by clicking the option arrow to the right of
the search field, selecting Find More Providers, and adding the search provider. As you type, the search will return the search results visually. You can also switch between the different search providers you have installed by clicking the icons below the search result.

Visual Search Providers
Currently, the following search providers support visual search:
• The New York Times Instant Search
• Wikipedia Visual Search
• Amazon Search Suggestions
• eBay Visual Search
• Bing Search Suggestions
• Freebase Visual Search
• Bidtopia Search Suggestions

One neat trick with IE is that the web address field is also a search box— just type the search string in it and the default search provider configured in IE will perform a search.

Web Slices
IE8 supports a new feature called Web Slices. Basically, Web Slices allows you to automatically monitor changes in the content of some pages without needing to revisit the page. Consider the case of bidding for an item on eBay. If you are currently bidding for an item, you would be very interested in monitoring its bids closely so that you know the latest price. Rather than refreshing the page continuously, IE8 can do that for you and alert you when the content of the page changes. When you go to sites that support Web Slices, you will see the Web Slices icon appear as your mouse moves over sections of the page. The RSS button will also turn into the Web Slices icon. See the two highlighted icons

When you click the Web Slices icon, you will be asked whether you want to view it from the Favorites. Click the Add to Favorites Bar button to add the Web Slices.

You can now view the Web Slice in the Favorites bar. Clicking it will display the portion of the page. When the content of the Web Slice has changed, the item in the Favorites bar will be displayed in bold and its background color will change.

To customize the behavior of Web Slices, go to the Command bar and select Tools->Internet Options. Under the Content tab, click the Settings button in the Feeds and Web Slices. You can now configure the frequency of the updates (ranging from once every 15 minutes to once every week).

Imagine that you are searching for the address of a particular location. Once the address is found, you would most likely copy the address and navigate to Google Maps (or LiveSearch Maps) to check out the map of the location. Wouldn’t it be easier if IE simply provided a link to automatically do just that?

Enter accelerators, a feature in IE8. Accelerators help you quickly accomplish tasks without needing to navigate to other websites. For example, if you want to check the map of a location, highlight the address, click the blue accelerator icon displayed on the screen, and select “Map with Bing” accelerator.

The map of the selected address will now be displayed. Another useful accelerator is the translation service provided by Live Search. You can add more accelerators to IE8 by right-clicking any web page, choosing All Accelerators, and clicking Find More Accelerators.

Source of Information : Oreilly Windows 7 Up and Running

Reading and Subscribing to Feeds in IE8

A feed delivers frequently updated web content to your browser on a continuous basis. A feed, also known as RSS (Really Simple Syndication) feed, XML feed, syndicated content, or web feed, is usually offered on a subscription basis and typically free of charge. A feed can deliver text content in the form of news headlines or blogs, or digital content in the form of pictures, audio, and video. When audio content is delivered usually in the MP3 format, it’s referred to as a podcast. When you visit a web site, Internet Explorer checks for available feeds. If it discovers a feed, the orange Feeds button appears in the Command bar. You can view an individual feed or subscribe to one to get content automatically. When you subscribe to a feed, Internet Explorer checks the web site and downloads new content so you always stay updated with the latest site content. You can also add an RSS feed to your Favorites bar, making it easy to view updates (New!). Internet Explorer manages a common feeds list, which allows other programs, such as email, to use them.

View and Subscribe to a Feed
1. Visit a web site with a feed. The Feeds button changes color and plays a sound.

TIMESAVER You can also press Alt+J to check for feeds.

2. Click the Feeds/Web Slices button arrow (New!) on the Command bar, and then select an available feed.

3. If available, click the feed you want to see. A web page opens, displaying a lists of articles and other elements you can read and subscribe to.

4. Click the Subscribe to this Feed button, and then click Subscribe to this Feed, if necessary.

5. Type a name for the feed, and then select a location for the feed.

6. To add the feed to the Favorites bar, select the Add to Favorites Bar check box (New!).

7. Click Subscribe.

View Subscribed Feeds
1. If available, click the feed button on the Favorites bar, and then click a specific feed (New!).
• If the feed button on the Favorites button is bold, the feed has been updated.

2. Click the Favorites Center button.

3. Click the Feeds button.

4. If needed, click a folder to display related feeds.

5. Click the feed to visit the web site for the feed.

6. Click off the pane or click the Close button.

What formats are feeds available in? The most common formats are RSS and Atom. All web feed formats are based on XML. XML (Extensible Markup Language) is a platform-independent universal language that enables you to create documents in which data is stored independently of the format. XML is a markup language just like HTML. You mark up a document to define the structure, meaning, and visual appearance of the information.

You can change feed settings. Click the Tools button, click Internet Options, click the Content tab, click Settings in the Feeds and Web Slices section, specify the options you want, and then click OK twice.

You can import favorites from another browser. Click the Favorites Center button, click the Add to Favorites button arrow, click Import and Export, and then follow the steps in the Import/Export wizard.

Resetting Internet Explorer Settings
If you installed another web browser after installing Internet Explorer, some of your Internet Explorer settings may have changed. You can reset your Internet Explorer settings to their original defaults, including your home page and search pages, and choice of default browser, without changing your other browser’s settings. To reset Internet Explorer settings, click the Tools button, click Internet Options, click the Advanced tab, click Reset, read the dialog box carefully, and then click Reset again.

Source of Information : Microsoft Windows 7 on Demand (2009)

Viewing and Maintaining a History List With Internet Explorer

Sometimes you run across a great web site and simply forget to add it to your Favorites list. With Internet Explorer there’s no need to try to remember all the sites you visit. The History feature keeps track of where you’ve been by date, site, most visited, or order visited today, which you can now sort by (New!). To view the History list, click the History button in the Favorites Center, select a sort option (New!), and then click a link (if necessary) in the pane to expand the list of web sites visited. You can also search for pages in the History list by typing keywords (New!). Because the History list can grow to occupy a large amount of space on your hard drive, it’s important to control the length of time you retain Web sites in the list. Internet Explorer deletes the History list periodically, based on the settings you specify. When you delete your History list, you can now protect and preserve your related data for trusted sites in your favorites list (New!).

View and Change the History List
1. Click the Favorites Center button on the toolbar.

2. Click the History button.

3. To change the history view, click the Sort button (New!), and then select the view option you want.
• View By Date.
• View By Site.
• View By Most Visited.
• View By Order Visited Today.
• Search History. (New!) Type a keyword to search for a page, and then click Search Now. Click Stop to end the search.

4. If view By Date, click a week or day to expand or compress the list of web sites visited.

5. If necessary, click the folder for the web site you want to view, and then click a page within the web site.

6. Click off the pane or click the Close button.

Change the Number of Days Pages Are Saved
1. Click the Tools button on the Command bar, and then click Internet Options.

2. Click the General tab.

3. In the Browsing history section, click Settings.

4. Specify the total number of days you want to keep links listed in

5. Click OK.

6. Click OK.

Clear the History List
1. Click the Safety button on the Command bar, and then click Delete Browsing History.
• You can also open this dialog by clicking Delete on the General tab in the Internet Options dialog box.
• To delete browsing history on exit, click the Tools button, click Internet Options, select the Delete browsing history on exit check box, and then click OK.

2. To preserve cookies and temporary Internet files for sites in your Favorites folder, which are trusted sites, select the Preserve Favorites website data check box (New!).

3. Select the History check box to clear the history list.

4. Click Delete.

Windows 7 Action Center

In Windows 7, Microsoft has designated the new Action Center as the one-stop place to find all your system maintenance and security messages. The key design goal of the Action Center is to help users solve system issues quickly and conveniently. The system tray is now less cluttered, compared with its appearance in previous versions of Windows—it now has four main icons: Action Center, Network, Speaker volume, and Date and Time. Mobile computers will have a power icon as well.

In particular, the Action Center icon (represented as a white flag, which will include a red “x” if there are important messages requiring your attention) replaces several notification icons from Vista, reducing much clutter. When you click the Action Center icon, a pop-up window displays a summary of system messages of varying importance levels. In addition, it also provides a way for you to resolve the error. To view the messages, click the message icons or click the Open Action Center link.

The Action Center will display the details of the messages along with a button to help you solve the issue.

Besides displaying messages on maintenance and security-related issues, the Action Center can also help you troubleshoot problems with your computer and restore your computer to its setup from an earlier time.

Messages are classified into two main categories: Security and Maintenance. Security messages relate to issues concerned with:
• Windows Update
• Internet security settings
• Network firewall
• Spyware and related protection
• User Account Control
• Virus protection

Maintenance messages relate to issues concerned with:
• Windows Backup
• Windows Troubleshooting
Messages can be important or normal. Important messages display notification balloons in the System tray in addition to appearing in Action Center. A good example of an important message balloon is what happens when the Windows Firewall is turned off.

In the Action Center, you can also expand on each message category to view the status of each Security- and Maintenance-related item for your computer. You have the option to prevent messages from displaying by clicking the Change Action Center settings link in the left side of the Action Center window. Uncheck the item(s) for which you do not want to view a message.

The Action Center is for displaying messages and resolving problems, not managing tasks. For example, you can use the Action Center to help you find an antivirus program, but you cannot manage your Windows Firewall in the Action Center.

Turning Off Action Center
If you do not want to see the Action Center in the System tray at all, you can turn it off.
Perform the following steps to turn Action Center off:
• Right-click the “Show hidden icons” button in the Notification Area and select “Customize notification icons.”
• Click the “Turn system icons on and off” link.
• For the Action Center icon, select Off.

Source of Information : Oreilly Windows 7 Up and Running (November 2009)

Using Compatibility View in Internet Explorer 8

If you visit an older web site that doesn’t display correctly—misaligned text, images, and text boxes—in Internet Explorer 8, you can quickly fix it, in most cases, with Compatibility view (New!). When you open an older site that Internet Explorer recognizes, the Compatibility View button appears in the Address bar, near the Refresh button. The button appears on a per site basis. However, once you click the button for a site, you don’t have to do it again. Internet Explorer maintains a list of sites with Compatibility view, which you can customize (New!).

Fix the Display of Older Web Sites
1. Open the older web page with the display you want to fix. If the Compatibility View button appears in the Address bar next to the Refresh button, the option is available (New!).

2. To fix the display of an older web site, click the Compatibility View button in the Address bar. A ScreenTip appears indicating Compatibility View is enabled.

3. To change Compatibility view settings, click the Tools button on the Command bar, and then click Compatibility View Settings.

4. To remove a site, select the site, and then click Remove.

5. To enable other options, select the check boxes you want.

6. Click Close.

You can browse using your keyboard. With caret browsing, you can use the navigation keys—Home, End, Page Up, Page Down, and the arrow keys. Press F7 or click the Page button, click Caret Browsing, and then click Yes.

Source of Information : Microsoft Windows 7 on Demand (2009)

Getting a Better Understanding of Windows 7 Libraries

When you work with libraries, it is important to remember that they are only representations of collected data. Windows 7 creates merged views of files and folders that you add to libraries. As the libraries themselves do not contain any actual data, any action you take on a file or folder within a library is performed on the source file or folder. You can create new libraries to act as views to various collections of data as needed by right-clicking the Libraries node in Windows Explorer, pointing to New and then selecting Library.

If you’re ever curious about how libraries really work, access the %HomeDrive%\
%HomePath%\AppData\Roaming\Micrdosoft\Windows\Libraries folder. In this folder, you’ll find the library definition files for your user profile. Each library definition file ends with the .library-ms extension and is formatted as an XML file that follows Microsoft’s Library naming schema. If you view a library definition file, you’ll find that it uses simple locations to define where contents in the library originate from. Folder and files are referenced by globally unique identifiers (GUIDs) and the serialized contents of a particular location are encrypted. Some properties of libraries are tracked in the registry, but these are primarily used only when you want to restore the original libraries, which you can do in Windows Explorer by right-clicking the Libraries node and selecting Restore Default Libraries.

Note also that the %Public%\Libraries folder also may have library definition files. For example, Windows Media Player and Windows Media Center both make use of the Recorded-TV library. As this library isn’t a standard library in your user profile, it is represented in the %Public%\Libraries folder by the Recorded-TV.library-ms file.

Source of Information : OReilly Windows 7 The Definitive Guide

Browsing Privately in Windows 7

If you’re using a computer at a friend’s house, another office, hotel, or an Internet cafe and you don’t want to leave any trace or evidence of your web activity, you can use InPrivate browsing (New!). InPrivate browsing doesn’t retain or keep track of browsing history, searches, temporary Internet files, form data, cookie, and usernames and passwords. You can start InPrivate browsing from a new tab or using the Safety button on the Command bar. When you start InPrivate browsing, Internet Explorer opens a new browser window. An InPrivate indicator icon appears in the Address bar when the feature is turned on. When you’re done, simply close the browser window to end the InPrivate browsing session.

Browse the Web Privately
1. Start an InPrivate browsing session using any of the following:
• Safety button. Click the Safety button on the Command bar, and then click InPrivate Browsing.
• New tab. Click the New Tab button to open a new tab, and then click Open an InPrivate Browsing window.
• Shortcut. Press Ctrl+Shift+P.

2. Browse the web. The InPrivate indicator appears in the Address bar.

3. To end InPrivate browsing, click the Close button to close the browser window.

Source of Information : Microsoft Windows 7 on Demand (2009)

Browsing the Web in Windows 7

A Web address (also known as a URL, which stands for Uniform Resource Locator) is a unique place on the Internet where you can locate a Web page. With Internet Explorer, you can browse sites on the Web with ease by entering a Web address or by clicking a link. Each method is better at different times. For example, you might type an address in the Address bar to start your session. Then you might click a link on that Web page to access a new site. When you type an Internet address in the Address bar, Internet Explorer uses AutoComplete to search for a recently visited page, favorite, and RSS feed that matches (New!) what you’ve typed so far. If Internet Explorer finds one or more matches, it displays a drop-down menu and highlights them in blue. You can also use AutoComplete to fill out forms on the Web, including single-line edits, and user names and passwords. When you visit a site, the Address bar highlights the domain name in black and leaves the remainder of the URL in gray (New!) to help you identify the site name, so you can avoid deceptive ones that try to mislead you.

View a Web Page
Use any of the following methods to display a Web page:

• In the Address bar, type the Web address, and then press Enter.
If you have recently entered the Web page address, AutoComplete remembers it and tries to complete the address for you. The smarter Address bar searches your history, favorites, RSS feeds, displaying a drop-down menu with matches from any part of the Web site address (New!). The suggested matches are highlighted in blue (New!). Click the correct address or continue to type until the address you want appears in the Address list. If you want to get rid of suggestions in the drop-down menu, you can delete them. Point to a menu item, and then click on the Delete button (red X) (New!).

• Click any link on the Web page, such as a picture or colored, underlined text. The mouse pointer changes to a hand when it is over a link.

Change AutoComplete Options
1. Click the Tools button, and then click Internet Options.

2. Click the Content tab.

3. Click Settings.

4. Select or clear the AutoComplete options you want to turn on or off.

5. To delete AutoComplete history, click Delete AutoComplete history, select the check boxes with the options you want, and then click Delete.

6. Click OK.

7. Click OK.

You can have AutoComplete quickly complete a web address. In the Address bar, type the name of the web site, such as perspection, and then press Ctrl+Enter. AutoComplete adds the “www.” and “.com”.

You can use the Address bar to search for information. In the Address bar, type go, find, or ? followed by a space and a word or phrase, and then press Enter. To turn off or change Address bar searches, click the Tools button, click Internet Options, click the Advanced tab, select options under Search from the Address bar, and then click OK.

You can display the menu bar and toolbars using the Tools button. If you want to display the menu bar and any toolbars, click the Tools button, point to Toolbars, and then click Menu Bar or a toolbar.

Understanding a Web Address
The address for a Web page is called a URL. Each Web page has a unique URL that is typically composed of four parts: the protocol (a set of rules that allow computers to exchange information), the location of the Web site, the name that maintains the Web site, and a suffix that identifies the type of site. A URL begins with a protocol, followed by a colon, two slashes, the location of the Web site, a dot, the name of the Web site, a dot, and a suffix. The Web site is the computer where the Web pages are located. At the end of the Web site name, another slash may appear, followed by one or more folder names and a file name. For example, in the web site address, downloads/main.htm, the protocol is http (HyperText Transfer Protocol), the location of the Web site is www (World Wide Web), the name of the Web site is perspection, and the suffix is com (a commercial organization); a folder at that site is called /downloads; and within the folder is a file called main.htm.

Source of Information : Microsoft Windows 7 on Demand (2009)

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