Commvault and Sophos large differentials (SOLUTION)

[mitmont]

We've been working on deploying Sophos in an large existing domain with Commvault 8.0. Our issue is that overnight the diffential backups increased 1000% per server. 3-4 TB amounts of data rather than 400-600GB per night.

Sophos is configured to scan every night at 3AM with on-access set to read and write. Commvault is configured to use the Change Journal for backups.

Tested by putting a couple of computers into a seperate group and not scanning every night. Differentials returned to the normal sizes. After the test we put the servers back in the original group and the differentials shot back up to the huge sizes. 600MB normals would be backups about 7-8GB. Over 120 servers the issue is compounded.

After the results I called Sophos of our tests and got the fix for the problem.
For 2003 server
You will need to create the following String key:

HKLM/Software/Sophos/SAVService/Application/ODScanUpdateMetadata
Set value to 0

For 2008 server
You will need to create the following String key:

HKLM/Software/WOW6432Node/Sophos/SAVService/Application/ODScanUpdateMetadata
Set value to 0

Caution is advised anytime you change registry settings.
Take all neccessary precautions.

Good luck