[Pacemaker] newbie question(s)

Lars Marowsky-Bree lmb at suse.com
Fri May 24 13:30:47 EDT 2013

On 2013-05-24T12:15:04, Digimer <lists at alteeve.ca> wrote:

> Nope. Until RHEL 5, openais was the communication layer of the cluster.
> However, the full AIS API was deemed "overkill" for what HA clustering
> needed, so corosync was created for RHEL 6 as a stripped-down, HA focused
> version of openais. In turn, openais was made a corosync plugin for those
> who actually want the full AIS API.

You know, there *is* a software community out there that doesn't use
RHEL. Really. ;-) At the time, this was actually a community decision
and not RHEL-driven. (Though of course the needs of RHEL also informed

The AIS APIs were mostly just not deemed worth the trouble. Outside a
very narrow field (Carrier Grade), very few people used them, and those
that did preferred the opensaf implementation. Hence, openais turned out
to not be worth the effort of long-term support for a rather complex set
of services and a *huge* specification.

OCFS2 and cLVM2 exist in an incarnation that uses the AIS CKPT
(checkpoint) service for synchronization, but that has been/will be
rewritten too.

> The concepts of "Active/Active", "Active/Passive", etc. is not a membership
> or cluster communication layer question. Those concepts come from the
> resource manager (rgmanager or pacemaker).

Yes - and no, because it neglects the detail that the AIS stuff does
include the notion of a limited cluster manager too. 


Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde

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