I have one VM that I cannot seem to nail down what is causing huge amounts of changed blocks on a daily basis. The guest is running 2008 R2, and is also a domain controller. It has to virtual disks, and the c: disk is the one that has around 24GB of changes backed up each job run. There are no file shares off of this drive aside the ones for AD. Here is what I have done to narrow down the issue thus far.
1. Turned off AV, no change.
2. Verified there are no scheduled tasks running.
3. Moved print spool folder to different drive (grasping at straws here).
4. Starting running backup job twice daily, would have thought my vib files would have been about half the size, but they stayed consistent.
5. Windows reports drive is about 50% fragmented. I have gone through other threads on here, and it seems to be that this could be a source but also may not matter. Some things say that this causes small file changes to create large amounts of changed blocks, others say to not worry about defragging a disk any more.
I have not tried turning off CBT, as I can guess it would make the files much smaller, it is not really a valid solution. I have other servers that i back up such as exchange, database servers, and other domain controllers that do not have any where near the size of changed blocks that this one does. I am at a loss of what else to look at on this system. Any ideas would be great!