[ClusterLabs] resource agent - wait for app data sync

[George Melikov]

Some apps's data may need to be synced before it's safe to promote/demote/standby.

For example - DRBD, it replicates data across servers, but if you shut down master server during resync - you'll have a split brain.

Is there a way to tell pacemaker from OCF agent that it's not safe now to do any migration?

Unfortunately, I didn't find anything about this case in https://github.com/ClusterLabs/resource-agents/blob/master/doc/dev-guides/ra-dev-guide.asc