As a cluster admin I would like to understand the effect that live flattening of my ODF volumes will have on my VM workloads when I enable Regional DR protection so that I can better plan for the disruption.

As part of enabling ODF Regional DR for PVCs that were created from either a CSI clone or a CSI Snapshot there will be a RBD flattening operation so that the mirrored RBD volume is independent. Naturally, this flattening operation will increase I/O since data is being copied. It may introduce other issues such as lock bouncing between the flattening process and the concurrent volume user(s).

We would like to see some measurements in order to assess the impact of flattening on a realistic VM workload so that we can provide the appropriate warnings and/or guidance to application owners regarding enabling DR.

This doc provides more details on how to manually flatten to simulate this effect without ODF DR.