[ClusterLabs] 3 nodes cluster on Centos 7

[Michael Schwartzkopff]

Am Dienstag, 7. Juli 2015, 12:25:56 schrieb Andrei Borzenkov:
> On Tue, Jul 7, 2015 at 12:19 PM, Nicolas S. <lists at tropicdreams.net> wrote:
> > Hello everybody,
> > 
> > I'm posting first time on this mailing list for an advice.
> > 
> > I try actually trying to build a cluster on Centos 7.
> > 
> > The cluster has 3 nodes :
> > 
> > - 1 virtual machine (machine1). This machine is supposed to be
> > high-available
> > - 2 physical machines identical (machine2 and 3)
> > 
> > The physical machines are supposed to use DRBD to replicate storage.
> > A shared volume is going to be mounted on both machine 2 and 3 in
> > read/write (gfs2).
> > 
> > The virtual machine is only here for the vote in the qorum, it has no data
> > .
> It's not going to work. If host where this VM is running goes down,
> quorum is lost.

No. 2 machines of 3 are alive. Cluser still will work.


> > I m' following this guide :
> > http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html/Clusters_from_Scra
> > tch/index.html
> > 
> > My questions are  :
> > 
> > - Is this configuration OK or shoud I better go to a 2 node only cluster ?
> 
> You need 2 node cluster with stonith.

It is ok. But you need fencing in any way. So perhaps the third virtual 
machine is not necessary.


> > - Is there a way to "group" the storage machines 2 and 3 and put some
> > ressources (like DRBD and GFS2) only on them ? So that  the machine 1 is
> > here , but does nothing, just vote.

Yes. Just configure location constraints so that resources will not run on the 
virtual machine.

> > I looked around in the pcs command line option but maybe i missed it.

Don't know about pcs. I am used to crmsh.

Mit freundlichen Grüßen,

Michael Schwartzkopff

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