Sage Weil wrote: <snip> > The main things that come to mind: > > - zfs checksumming > - ceph can eventually use zfs snapshots similarly to how it uses btrfs > snapshots to create stable checkpoints as journal reference points, > allowing parallel (instead of writeahead) journaling > - can use raidz beneath a single ceph-osd for better reliability (e.g., 2x > * raidz instead of 3x replication) > > ZFS doesn't have a clone function that we can use to enable efficient > cephfs/rbd/rados snaps, but maybe this will motivate someone to implement > one. :) Since Btrfs has implemented raid5/6 support (meaning raidz is only a feature gain if you want 3x parity, which is unlikely to be useful for an OSD[1]), the checksumming may be the only real benefit since it supports sha256 (in addition to the non-cryptographic fletcher2/fletcher4), whereas btrfs only has crc32c at this time. [1] A raidz3 with 4 disks is basically raid1, at which point you may as well use Ceph-level replication. And a 5-or-more-disk OSD strikes me as a questionable way to set it up, considering Ceph's strengths. -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
