What is SQL Server in an Azure virtual machine (IaaS)?

Running SQL Server in an Azure VM is similar to running SQL Server in a virtualized environment in your own data center or in a traditional hosting environment, except that Microsoft provides the hardware on which the virtual machine runs and provides an availability SLA of 99.95 percent. You are in charge of, responsible for, and have either some or complete control of:

 Choosing the amount of compute resources: Many virtual machine size options

 Choosing and configuring storage: Many storage options

 Choosing an operating system: Many versions, including Windows (SQL Server only runs on Windows)

 Choosing the version of SQL Server: Any version of SQL Server

 Choosing SQL Server license model: Choose preinstalled version with per-minute licensing or bring your own license with SA

 Managing the virtual machine: Manage the virtual machine itself via Remote Desktop Protocol (RDP), PowerShell, or CLI

 Managing SQL Server: Manage SQL Server using SQL Server Management Studio or any other SQL tool you wish

 Securing the virtual machine: Manage firewalls and access using standard Windows methods, including choosing to join a domain (directly or using Azure Active Directory)

 Securing SQL Server: Manage authentication and access using standard SQL Server methods

 Optimizing virtual machine performance: Tune the virtual machine using standard virtual machine tuning methodologies

 Optimizing SQL Server performance: Tune the SQL Server instance using standard SQL Server tuning methodologies

 Managing costs: Dynamically scale up and scale down the virtual machine size as computer power is needed, and add or remove disks as storage and throughput is needed

 Patching the operating system: Your responsibility

 Patching SQL Server: Your responsibility, but Microsoft provides tooling to assist

 Backing up SQL Server databases: Your responsibility, but Microsoft provides tooling to assist

 Managing availability: Microsoft ensures the availability of the VM itself within a single data center, but all additional availability is your responsibility with Microsoft providing tooling to assist (see AlwaysOn Availability Groups).

As you can see, with SQL Server on an Azure VM, you have great ability to configure and manage SQL Server in a VM in a manner similar to how you currently manage IT resources in your on-premises environment.

Source of Information : Migrating SQL Server Databases to Azure