[Pacemaker] Does pingd works on openais?

Serge Dubrouski sergeyfd at gmail.com
Fri Mar 7 14:30:27 EST 2008

On Fri, Mar 7, 2008 at 12:17 PM, Lars Marowsky-Bree <lmb at suse.de> wrote:
> On 2008-03-07T20:11:46, Atanas Dyulgerov <atanas.dyulgerov at postpath.com> wrote:
>  > Hm, I left with the impression openais is part of the red hat cluster suite in some way: http://sources.redhat.com/cluster/faq.html#what
>  Check question 12 ;-)
>  > >That's something the resource agents would need to do. And as far as I
>  > >know, openAIS does not do the resource level locking you refer to; but
>  > >Pacemaker internally ensures exclusive access to them.
>  > Yes, Pacemaker should support resource locking.
>  But it does. Pacemaker already "locks" the resources to one node, and
>  orders fencing, STONITH, start/stop etc as needed to ensure that
>  resources are not running where they aren't allowed to.That's what a
>  cluster resource manager is all about.
>  I'm not sure what more you are asking for?

In fact I'm afraid that CRM lacks one feature that other clustering
projects have. It's that quorum disk. In RedHat ClusterSuite or in HP
ServiceGuard quorum disk helps to fight split brain scenario. It's not
clear how CRM acts when heartbeat link gets broken and nodes can't
communicate to each other. What I see in my logs both nodes try to
STONITH each other which isn't the best way to handle this problem.

Please do not mistake quorum drive (feature for local cluster) with
quorumd server which was designed for  geographically spread clusters.

>  > So you are saying that Heartbeat replaces successfully all of the above? Can OCFS2 get its membership information from Heartbeat? Does Heartbeat CRM controls OCFS2 distributed lock manager?
>  >
>  > If true, could you send me some links for that? Patches, docs, sample configuration in Heartbeat? Thanks!
>  We've got that working in SLES10. The patches are all open source (of
>  course), and the user-space membership code is supposedly merged
>  upstream in OCFS2 by now.
>  On the heartbeat/Pacemaker side, it is as easy as configuring the
>  Filesystem resource for the ocfs2 mount, just as a clone.
>  > >That is going to work just fine, though if you're using GFS2 or OCFS2 on
>  > >top of GNBD or iSCSI (because you don't have a SAN, presumably), I'd
>  > >really wonder why you're not directly using NFS?
>  > Hm? GFS and GNBD works with red hat cluster suite only?
>  GFS yes; GFS2 will eventually work with Pacemaker as well.
>  > I don't have SAN. I'm looking for a cheaper solution. The reason I'm
>  > not using NFS is the slower performance compared to the fastest GNBD
>  > and iSCSI.
>  Have you _benchmarked_ that for your workload? iSCSI/GNBD are
>  block-level protocols, that means a higher overhead over the network.
>  And because OCFS2/GFS2 do their own locking, the nodes also have a fair
>  bit of additional internode communication.
>  > Also a very specific service application is running on the cluster and
>  > it does not get along with NFS very well.
>  What kind of features does it use that don't get along with NFS? In
>  theory, NFSv4/3 should be 1:1 compatible?
>  > To lock the network block device if node fails to bring down the
>  > service application or if for any reason the cluster software fails on
>  > that node. In that case the application will be started on a passive
>  > node and the cluster might end up with two nodes which try to access
>  > the same data.
>  Pacemaker/Heartbeat handle this through fencing/STONITH. It'd of course
>  be fatal if not.
>  > >>    - OCFS2 is not completely stable and it is driven by its own cluster
>  > >OCFS2 is not completely stable?
>  > That's what I read on various forums... not my personal experience.
>  Ah. Rumors. ;-)
>  Regards,
>     Lars
>  --
>  Teamlead Kernel, SuSE Labs, Research and Development
>  SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
>  "Experience is the name everyone gives to their mistakes." -- Oscar Wilde
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Serge Dubrouski.

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