On Tue, 2 Oct 2012, Mike Ryan wrote: > Tried sending this earlier but it seems the list doesn't like PNGs. > dotty or dot -Tpng will make short work of the .dot file I've attached. > > > These are the changes to the Active state of the PG state chart in order > to support recovery reservations. This is Important Stuff, so please > criticize mercilessly. > > Here's a prose version: > > When the PG activates, it determines whether it needs to do recovery. If > it does, it grabs its local reservation, then grabs a remote reservation > from each replica in order of OSD ID (to prevent deadlock). Once all > remotes are reserved, it starts recovering. > > After recovery, all remote reservations are dropped. If no backfill is > necessary, the local reservation is dropped and we jump to Clean. > > If we need to backfill, we request a remote backfill reservation from > the replica. If this reservation is rejected (due to the OSD being too > full) we drop our local reservation and wait for a while in > NotBackfilling. We then grab our local reservation and try again on the > remote reservation. Once we have the remote reservation, we backfill. > After Backfilling we drop the local and remote backfill reservation and > jump to Clean.
This all looks right to me. I only have one concern: if, at some future point, we decide it's necessary or worthwhile to avoid non-backfill recovery due to targets begin full, does this approach preclude an elegant solution? sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
