The following table summarizes how PX will respond to an etcd disaster and its recovery from a previous snapshot.

PX state when snapshot was takenPX state just before disasterPX state after disaster recovery
PX running with few volumesNo PX or application activityPX is back online. Volumes are intact. No disruption.
PX running with few volumesNew volumes createdPX is back online. New Volumes are lost.
PX volumes were not in use by application. (Volumes are not attached)Volumes are now in use by application (Volumes are attached)PX is back online. The volume which was supposed to be attached is in detached state. Application is in CrashLoopBackOff state. Potentially could lead to data loss.
PX volumes were in use by applicationVolume are now not in use by applicationVolumes which are not in use by the application still stay attached. No data loss involved.
All PX nodes are upNo PX ActivityAll the expected nodes are still Up
All PX nodes are upA few nodes go down which have volume replica. Current Set changes.Potentially could lead to data loss/corruption. Current Set is not in sync with what the storage actually has and when PX comes back up it might lead to data corruption
A PX node with replica is down. The node is not in current set.The node is now online and in Current Set.PX volume starts with older current set, but eventually gets updated current set. No data loss involved.