How to configure DFSR file-type compression in Windows Server 2008

This article describes how to configure Distributed File System Replication (DFSR) file-type compression in Windows Server 2008.

In Windows Server 2008, you can use DFSR to configure the compression of files by file type. This differs from the version of DFSR in Windows Server 2003 R2. In Windows Server 2003 R2, DFSR has the following hard-coded extension list:

• .wma
• .wmv
• .zip
• .jpg
• .mpg
• .mpeg
• .m1v
• .mp2
• .mp3
• .mpa
• .cab
• .wav
• .snd
• .au
• .asf
• .wm
• .avi
• .z
• .gz
• .tgz
• .frx

Notes

• File compression in DFSR uses the XPRESS compression format in the DFSR staging area. XPRESS compression differs from Remote Differential Compression (RDC). RDC uses over-the-wire delta replication of file blocks.
• Generally, it is not useful to perform additional compression on files that are already compressed.
• Beginning in Windows Server 2008 R2, the default list also includes file extensions .docx, .xlsx, and .pptx.

You can prevent the compression of specific file types by using the msDFSR-DefaultCompressionExclusionFilter attribute. To do this, follow these steps:

1. Click Start
   , type adsiedit.msc in the Start Search box, right-click cmd in the Programs list, and then click Run as administrator.
   
   
   If you are prompted for an administrator password or for confirmation, type the password, or click Continue.
2. In the ADSI Edit snap-in, expand the domain node.
3. Locate a DFSR content set. For example, locate the following:
   CN=SYSVOL Share,CN=Content,CN=Domain System Volume,CN=DFSR-GlobalSettings,CN=System,CN=Domain name,CN=com
4. Right-click CN=SYSVOL Share, and then click Properties.
5. Click the msDFSR-DefaultCompressionExclusionFilter attribute, and then click Edit.
6. In the Value box, type a comma-separated list of file name extensions that you do not want to be compressed when DFSR stages a file. For example, type the following:
   wma,wmv,zip,jpg,mpg,mpeg,m1v,mp2,mp3,mpa,cab,wav,snd,au,asf,wm, avi,z,gz,tgz,frx,docx,pptx,xlsx,dcm
   Note�This list contains the�default list of file extensions from Windows Server 2008 R2 and the .dcm file type. A .dcm file is a compressed medical image file.
7. Click OK two times.
8. Close the ADSI Edit snap-in.

All files that have an extension that is listed in the msDFSR-DefaultCompressionExclusionFilter attribute will no longer be compressed in the staging directory.

If the msDFSR-DefaultCompressionExclusionFilter attribute is configured as <Not Set>, the default hard-coded extension list will be used based on the operating system. If you make any changes to the attribute, the default�exclusion list is completely ignored in Windows Server 2008 and newer.

Note Always include the default exclusion list when you customize the settings.