[Gluster-users] ZFS with SSD ZIL vs XFS

[Jeff Darcy]

On Tue, Oct 10, 2017, at 11:19 AM, Gandalf Corvotempesta wrote:
> Anyone made some performance comparison between XFS and ZFS with ZIL
> on SSD, in gluster environment ?
> 
> I've tried to compare both on another SDS (LizardFS) and I haven't
> seen any tangible performance improvement.
> 
> Is gluster different ?

Probably not.  If there is, it would probably favor XFS.  The developers
at Red Hat use XFS almost exclusively.  We at Facebook have a mix, but
XFS is (I think) the most common.  Whatever the developers use tends to
become "the way local filesystems work" and code is written based on
that profile, so even without intention that tends to get a bit of a
boost.  To the extent that ZFS makes different tradeoffs - e.g. using
lots more memory, very different disk access patterns - it's probably
going to have a bit more of an "impedance mismatch" with the choices
Gluster itself has made.

If you're interested in ways to benefit from a disk+SSD combo under XFS,
it is possible to configure XFS with a separate journal device but I
believe there were some bugs encountered when doing that.  Richard
Wareing's upcoming Dev Summit talk on Hybrid XFS might cover those, in
addition to his own work on using an SSD in even more interesting ways.