Am Mon, 14 Dec 2015 10:10:51 +0100 schrieb Martin Steigerwald <mar...@lichtvoll.de>:
> > But the problem is, when recovering journal, there is no journal of > > journal, to keep journal recovering safe from power loss. > > But the journal should be safe due to a journal commit being one > sector? Of course for the last changes without a journal commit its: > The stuff is gone. This may not be true for disks having write caching enabled and write barriers of. Then there's no barrier at a journal checkpoint. Next thing is: At least for ext4, journal is meta-data only. But I think what was meant here: The case of powerloss during log-replay... Tho I think the journal should simply be fully replayed again if it wasn't marked clean before. Which turns us back to write barriers and write caching... ;-) It could be that the checkpointing (or marking the journal clean after replay) could make it do disk before the actual data made it to disk, due to write-reordering of the hard disk - which can be effectively circumvented by disabling write caching and enabling write barriers (the latter should be default while I would always check the former). -- Regards, Kai Replies to list-only preferred. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
