Hi,
If I understand correctly, the scenario is:
1. VM is enabled for replication using vSphere Replication.
2. Backup software is used on the source VM.
3. When performing restore on the source VM using the backup software, it tries to change the size of some of the replicated disks.
4. vSphere Replication does not support changing the size of replicated disks. Replication needs to be unconfigured, then the disk resized and then replication configured again.
Peter,
which backup software are you using and does it change the size of the VM disks?
Regards,
Martin