[Linux-cluster] relationship corosync + dlm + cman in cluster 3.1.3

Jeroen Koekkoek j.koekkoek at perrit.nl
Tue Jun 28 07:12:29 UTC 2011


Hi Andrew,

Thanks for answering my question. While looking at the current source tree, I noticed newer versions, at least dlm_controld, will not use cman anymore. So I'll keep using 3.0.12 for now (with dlm_controld.pcmk). Do you have any estimate on the first release without cman?

Regards,
Jeroen

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com [mailto:linux-cluster-
> bounces at redhat.com] On Behalf Of Andrew Beekhof
> Sent: Monday, June 27, 2011 1:24 AM
> To: linux clustering
> Subject: Re: [Linux-cluster] relationship corosync + dlm + cman in
> cluster 3.1.3
> 
> On Wed, Jun 22, 2011 at 5:55 PM, Jeroen Koekkoek <j.koekkoek at perrit.nl>
> wrote:
> > Hi,
> >
> > I have a question regarding the relationship between Corosync, DLM,
> and CMAN. Is the following statement correct?
> >
> > The DLM is a kernel module, dlm_controld is the control daemon.
> > CMAN is the old messaging layer, and is now stacked on OpenAIS, which
> in turn is stacked on Corosync.
> >
> > The DLM does not use CMAN (or Corosync for that matter) to
> communicate, but does fetch node information from CMAN.
> >
> > The filesystem (GFS or OCFS2) speaks to the DLM locally (in kernel?)
> and the DLM takes care of the communication.
> >
> >
> > Now for the real question.
> >
> > In the 3.1.3 release dlm_controld still depends on CMAN, but is it
> safe to say that I can just use Pacemaker and Heartbeat resource agents
> and only install CMAN so that dlm_controld can query node information?
> >
> > Or did I misunderstand the documentation?
> 
> You need to make sure everyone is getting the same membership and quorum
> information.
> So yes, install CMAN for dlm_controld but also tell pacemaker to use it
> too (make sure you're on 1.1.5 or higher).
> 
> >
> > Regards,
> > Jeroen
> >
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> >
> 
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