Hi,
I can read that PCSM can be used for disaster recovery.
So i will test it for this scenario.
I read the documentation, “finalize” closed the migration process but in a disaster recovery
My goal is to never finalize operation, I don’t want to restart the init phase each time.
So, my question:
If the source is down and the target are not finalized (maybe not completely sync and indexes are not full operational), Can the target database be operational after manual operation (index reconstruction, etc) without the “finalize” command?
Maybe, when we must understand “disaster recovery” like a database copy with finalize command and before the source is down rather?
C.
Hello @christopheL ,
PCMS currently doesn’t support Disaster Recovery in the classical sense, that the target is ready to take traffic as soon as the source crashes. Sorry for misleading docs, we’ll fix it immediately.
Currently PCSM requires this finalization step, where we update some temp changes we maintain for certain indexes during the sync. See here details for finalize step: How PCSM works - Percona ClusterSync for MongoDB
With that said, target is not schema consistent with the source until finalize is performed.
But, related to your question, yes, the target is fully operational if you manually perform operations that were not done during finalization.
Because finalize treats only certain indexes (hidden, unique and TTL), if you for example don’t have these indexes at all, then you could technically just call pcsm pause to pause the replication and start consuming from the target. Reason is that finalize essentially just pauses replication and handles mentioned indexes.
Also, in our next releases we have initiative to implement proper disaster recovery handling with PCSM (https://perconadev.atlassian.net/browse/PCSM-331).
Hope this helps,
Inel