On Mon, 2019-02-11 at 09:22 +0100, Dan van der Ster wrote: > Hi all, > > Does anyone know if ceph and level/rocksdb are already immune to these > fsync issues discovered by the postgresql devs? > > https://fosdem.org/2019/schedule/event/postgresql_fsync/ > https://wiki.postgresql.org/wiki/Fsync_Errors > https://www.postgresql.org/message-id/flat/CAMsr%2BYHh%2B5Oq4xziwwoEfhoTZgr07vdGG%2Bhu%3D1adXx59aTeaoQ%40mail.gmail.com > > Cheers, Dan Great question. I took a brief look at the rocksdb code but wasn't able to draw a meaningful conclusion there. I do see that you can set it up to use O_DIRECT, but it's not clear to me that propagates fsync errors in a meaningful way if you don't. I'm also not sure how ceph configures rocksdb to operate here either. I think it'd be good to reach out to the rocksdb developers and see whether they've considered its behavior in the face of a writeback failure. I'm happy to discuss with them if they have questions about the kernel's behavior. Cheers, -- Jeff Layton <jlayton@xxxxxxxxxx>
