We have MS DPM 2019 UR3 server (build 10.19.458.0) protecting some Hyper-V hosts. Recently I noticed strange backup behavior - some tasks transfer way more data than the entire virtual machine have. As an example, right now I have running backup task which already shows 1.15TB in the "data transferred" column while the combined size of all VM's vhdx files is about 800 GB.
The VM holds file server role and actual entire data footprint inside is less than 400GB. The previous successful backup task showed 845GB of transferred data, then there was task which failed with error "DPM failed to communicate with the protection agent on [DPM SERVER] because the agent is not responding. (ID 43 Details: Internal error code: 0x8099090E)", then we have current task which transferred 1.1TB and still running.
What can be the reason of such behavior?