Antivirus scan exclusions

Read this blog post: http://blogs.technet.com/b/jeff_stokes/archive/2010/05/19/anti-virus-exclusions-and-you.aspx

Read also the following links:
http://myitforum.com/cs2/blogs/scassells/archive/2007/05/14/what-anti-virus-scanning-exclusions-should-be-considered-for-system-and-servers.aspx
http://www.hypervizor.net/2010/03/configure-antivirus-exclusions-for.html
http://support.microsoft.com/kb/961804
http://support.microsoft.com/kb/822158

On any Hyper-V host you will find a couple of core processes that is crucial to host and VM performance. Prevent the following processes from AV scans by excluding the following as part of you Hyper-V AV policy.

VMMS.exe
VMWP.exe

You also want to exclude the root directories where VM configurations and Virtual Hard Disks are stored. Exclude the following directories.

C:\ProgramData\Microsoft\Windows\Hyper-V
C:\Users\Public\Documents\Hyper-V\Virtual Hard Disks
Custom VM configuration, Virtual Hard Disk and Snapshot directories

Next, you want to create AV exclusions for the following file extensions.

*.XML
*.VHD
*.AVHD
*.VFD
*.VSV
*.ISO

Finally, if you are using Hyper-V R2’s Live Migration feature with Cluster Shared Volumes, then you will need to exclude the CSV path and any sub-directories. The CSV path is as follows.

C:\Clusterstorage

Failure to create this exclusion on hosts using CSV, can not only result in poor performance, but can also result in a missing or corrupt VM configuration