On Tue, Jun 23, 2015 at 9:50 AM, Erik Logtenberg <e...@logtenberg.eu> wrote: > Thanks! > > Just so I understand correctly, the btrfs snapshots are mainly useful if > the journals are on the same disk as the osd, right? Is it indeed safe > to turn them off if the journals are on a separate ssd?
That's not quite it...it *is* safe to turn off btrfs snapshots, but by doing so you get the same behavior as XFS does by default. With btrfs snapshots enabled the OSD uses snapshots for consistent checkpoints and doesn't need to be quite as careful in its ordering of writes to the backing filesystem versus the journaling. Our use of snapshots is pretty abusive though, so you may well find better performance without them. :( The location of the journal on- or off-disk has nothing to do with it, though. :) -Greg _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
