[Pacemaker] offtopic scalable block-device

[Florian Haas]

On Fri, Mar 16, 2012 at 12:42 PM, Lars Marowsky-Bree <lmb at suse.com> wrote:
> On 2012-03-16T11:28:36, Florian Haas <florian at hastexo.com> wrote:
>
>> > is there a reason for integrating ceph with pacemaker? ceph does
>> > internal monitoring of OSTs etc anyway, doesn't it?
>> Assuming you're referring to OSDs, yes it does. It does automatic
>> failover for MDSs (if you use them) and MONs too. But it currently has
>> no means of recovering an osd/mds/mon daemon in place when it crashes,
>> and that's what those RAs do. Really trivial.
>
> Yes, I need to stop calling them OSTs, but that's what object storage
> targets were called before ceph came along ;-) Sorry. Yes, of course, I
> mean OSDs.
>
> Would this not be more readily served by a simple while loop doing the
> monitoring, even if systemd/upstart aren't around? Pacemaker is kind of
> a heavy-weight here.

If you prefer to suggest a self-hacked while loop to your customers
I'm not stopping you.

>> The ocf:ceph:rbd RA by contrast serves an entirely different purpose,
>> and I currently don't see how _that_ would be replaced by upstart or
>> systemd. Unless either of those becomes so powerful (and
>> cluster-aware) that we don't need Pacemaker at all anymore, but I
>> don't see that happen anytime soon.
>
> Agreed. I was mostly curious about the server-side. Thanks for the
> clarification.

I forgot to add, if you actually want to use a ceph _filesystem_ as a
cloned Pacemaker resource, ocf:heartbeat:Filesystem now has support
for that too. But that was just a trivial three-line patch, so nothing
new there.

Florian

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