I wrote about this issue on the vSphere blog some time back. Essentially, the issue described in that post was if a VM that was being replicated via vSphere Replication was migrated to another datastore, it triggered a full resync because the persistent state files (psf) which tracks the changes were deleted. All of the disks contents are then reread and check-summed on each side. This can have a significant impact on vSphere Replication’s RPO (Recovery Point Objective).
In vSphere 5.5 the psf files are now moved with the virtual machine and retain its current replication state. This means that virtual machines at the production site may now be Storage vMotion’ed, and conversely, participate in Storage DRS datastore clusters without impacting the RPO.
OK, that’s the protection site looked at. What about the recovery or DR site? Interoperability at the recovery site has not changed in vSphere 5.5. As I reported in the vSphere blog post, Storage DRS does not see the replica disks at the destination. These are just “disks”; there is no “virtual machine” that can be worked upon. The disks are not actually attached to a VM until “test” or “fail-over” time. Therefore Storage DRS cannot move these disks since it needs to work at the VM level. We of course would like Storage DRS to see the replica disks and be able to move them around if a datastore is filling up at the recovery site but we do not have this functionality right now.