I have a 3 very small offices configured identical. Each office has 10 users and a single 2012r2 hyper-v host server with 2 4TB drives. The VMs consist of 2 2012r2 DCs, one of which is a file server, the other is just a failover for DHCP, and a windows 8.1 VM that runs an indexing application. The file server has a 2TB dynamic vhdx, of which about 1TB is used file the file share shared via Microsoft distributed file system. The other DC for failover DHCP has a 128G dynamic vhdx disk. The Windows 8.1 VM is an 80G dynamic vhdx disk and all it does is run a small indexing application at night to update a local search database that the users can access to search the file share. It's search index is about 100 megabytes. The users create at most 30 megabytes of data per day, as most of their content is letters generated from MS Word templates.
When VEEAM B&R 8 runs in the evening, as an example of friday night's backup, that in each of the offices about 70G was read and 25G of data was transferred to the local office's backup repository. I have the backups configured as reverse incremental, enable inline de-dupe, exclude swap file blocks, compression level extreme, storage optimization WAN target.
I'm not sure why my servers having very little change in day-to-day data, are creating huge nightly backups. Where should I start looking to troubleshoot this?