Den mån 17 maj 2021 kl 08:15 skrev Szabo, Istvan (Agoda) < Istvan.Szabo@xxxxxxxxx>: > What happens if we are using buffered_io and the machine restared due to > some power failure? Everything that was in the cache will be lost or how > ceph handle this? > Not to be picky, but between any client writing data to storage and the magnetic layers of a drive there are some 8-9-10 layers of caches and buffers, and a varying degree of lying to the layer above on when data actually hits the spinning rust. Just because we found yet another one here which may or may not impact writes, it doesn't change the situation in the larger scheme. If power goes, any IO in flight will be disrupted in some way, either it will be finalized if possible or reverted if not, where reverted might be as late as "on the subsequent fsck/scrub over that part of the disk". The WAL/DB/Journals help a bit in figuring out if it can be finalized and what was in flight before the crash, but all in all, this is not totally unexpected from a storage point of view. Most often I guess the IO will be counted as not-done and when the OSD comes back, it will get the correct data replayed from another PG replica during recovery/backfill and that's more or less it. -- May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
 |