[Pacemaker] newbie question(s)

Andrew Beekhof andrew at beekhof.net
Sun May 26 20:35:50 EDT 2013

On 25/05/2013, at 2:15 AM, Digimer <lists at alteeve.ca> wrote:

> On 05/24/2013 11:24 AM, Nick Khamis wrote:
>> Was there not a time where corosync was a subset of OpenAIS? Namely,
>> openais support for active/active and passive/active? I might have my
>> channels mixed up, it's been a while....
>> @#linux-cluster and #linux-ha: Will do.
>> Ninus Khamis (PhD)
>> PS Sorry for the hijack!!!!
> 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.

Sort of. You're both right.
The AIS APIs were always plugins.

Essentially the core parts of OpenAIS were removed and called Corosync, while the plugins implementing the AIS APIs were left in place and deprecated.
So in that sense, Ninus is correct.

As for the "for RHEL" part, I think it was more a cost/benefit call by Steve who saw a lot of effort going into something that was largely unused.

> 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). More to the point, it's a per-resource question. You can have a pacemaker cluster where some services are Active/Active (ie: a GFS2 partition) while at the same time having an Active/Passive resouce (ie: a VM).
> hth
> digimer
> -- 
> Digimer
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