The process to fail back is structurally the same as an initial recovery; the only difference is that this workload has already been recovered at least once. So fundamentally the process is the same. Since the workload is going back to a place it has already been, the recovery process will attempt to re-use those resources (protection groups/volumes/volume groups).
The assumption is that the VMs were originally on site "A" and have been recovered to site "B". When the VMs are failed back to site "A":
Volume re-use:
- For a volume to be re-used, it must still be in the original replication group that it was failed over from (it can simultaneously be in other protection groups as well)
- If one or more volumes are not present in the original protection group, new volumes and volume groups will be created for the recovered VMs. Therefore the original volumes can be destroyed as they are no longer going to be re-used
- If a VM has been added to the replication after recovery, all volumes and groups will be re-used upon failback (assuming the above requirements are met too). The new VM will have new volumes and a volume group created
- If a VM is deleted after a reprotect, all volumes and groups will be re-used upon failback (assuming the above requirements are met too) and the corresponding volumes for the deleted VMs will be destroyed to correct what volumes reside on the recovered site
Protection group re-use:
- If no protection group that matches is found a new protection group is created
- If a matching protection group is found but that protection group membership has changed (volumes manually added or removed) that group will be ignored and new one will be created
- A matching protection group is not manually created (the match is not based on configuration or name)--it is created by VASA and the pair is maintained by VASA
- Matched protection groups will be overwritten with the protection policy of the source protection group
- Replication and snapshot policies will be disabled upon failover, and re-enabled as originally configured upon reprotect