File Server Resource Manager (FSRM) was a feature pack add-in to Windows 2003 R2 and has been significantly improved with the release of Windows Server 2008 R2. FSRM is a quota management system of files on network shares across an enterprise. Rather than allowing employees to copy the entire content of their laptop to a network, or potentially back up their MP3 audio files onto a network, FSRM provides the ability to not only limit the amount of content stored on network shares, but also to set quotas (or limit storage altogether) on certain file types. So, a user could be limited to store 200GB of files on a network share, but of that limit, only 2GB can be allocated to MP3 files.
FSRM, in Windows Server 2008 R2 has been improved to allow the nesting of quotas to ensure the most restrictive policy is applied. Quotas can also transcend subfolders, so as new folders are created, or as policies are applied at different levels in a folder hierarchy, the policies still apply, and the rules are combined to provide varying levels of quota allocation to user data. Additionally, quotas are now based on actual storage, so if a file is compressed when stored, the user will be able to store more files within their allocated quota.
Source of Information : Sams - Windows Server 2008 R2 Unleashed