[rhos-list] RHOS and Ceph

[Pete Zaitcev]

On Fri, 19 Apr 2013 18:03:12 +1200
Steven Ellis <sellis at redhat.com> wrote:

> One of their key questions is when (note when, not if) will Red Hat be
> shipping Ceph as part of their Enterprise Supported Open Stack
> environment. From their perspective RHS isn't a suitable scalable
> backend for all their Open Stack use cases, in particular high
> performance I/O block

Okay, since you ask, here's my take, as an engineer.

Firstly, I would be interested in hearing more. If someone made up their
mind in such terms there's no dissuading them. But if they have a rational
basis for saying that "high performance I/O block" in Gluster is somehow
deficient, it would be very interesting to learn the details.

My sense of this is that we're quite unlikely to offer a support
for Ceph any time soon. First, nobody so far presented a credible case
for it, as far as I know, and second, we don't have the expertise.

I saw cases like that before, in a sense that customers come to us and
think they have all the answers and we better do as we're told.
This is difficult because on the one hand customer is always right,
but on the other hand we always stand behind our supported product.
It happened with reiserfs and XFS. But we refused to support reiserfs,
while we support XFS. The key difference is that reiserfs was junk,
and XFS is not.

That said, XFS took a very long time to establish -- years. We had to
hire Dave Cinner to take care of it. Even if the case for Ceph gains
arguments, it takes time to establish in-house expertise that we can
offer as a valuable service to customers. Until that time selling
Ceph would be irresponsible.

The door is certainly open to it. Make a rational argument, be patient,
and see what comes out.

Note that a mere benchmark for "high performance I/O block" isn't going
to cut it. Reiser was beating our preferred solution, ext3. But in the
end we could not recommend a filesystem that ate customer data, and stuck
with ext3 despite the lower performance. Not saying Ceph is junk at all,
but you need a better argument against GlusterFS.

-- Pete