Snapshots currently use the SnaphotHfileCleaner and SnapshotHLogCleaner to ensure that any hfiles or hlogs (respectively) that are currently part of a snapshot are not removed from their respective archive directories (.archive and .oldlogs).
From Matteo Bertozzi:
currently the snapshot cleaner is not in hbase-default.xml
and there's no warning/exception on snapshot/restore operation, if not enabled.
even if we add the cleaner to the hbase-default.xml how do we ensure that the user doesn't remove it?
Do we want to hardcode the cleaner at master startup?
Do we want to add a check in snapshot/restore that throws an exception if the cleaner is not enabled?