Microsoft recently issued this KB article that outlines an issue with volumes that are created in multiples of 8gb, and volumes that are extended with multiples of 8gb. http://support.microsoft.com/kb/2748349. When creating backups of these volumes using VSS, corruption can occur, and 3rd party backup software may not detect the corruption until the file is recovered. This applies to Windows backup tools as well. There is a patch available at the same link, and it’s important to note that there are some specific paths to rectify this on Avamar. This is because of the way Avamar handles files it has previously backed up. When Avamar processes a file system, it may not trigger the backup of a file that was previously backed up despite the patch from Microsoft being applied. The EMC KB provides a work around within Avamar to solve this.