On 17/07/14 01:41 PM, Alex Samad - Yieldbroker wrote:
-----Original Message-----
From: Digimer [mailto:li...@alteeve.ca]
Sent: Thursday, 17 July 2014 2:02 PM
To: The Pacemaker cluster resource manager
Subject: Re: [Pacemaker] clusters on virtualised platforms
Don't confuse quorum and fencing (stonith), they serve different purposes.
Basically, quorum is useful when things are working, fencing is required when
things go wrong. So regardless of quorum disk, you still need to be able to
fence. This requires that each VM be able to call the hypervisor and force a
power off.
TA, yep got that, I was thinking and writing ..
Generally speaking, VM-based cluster nodes are good for learning, but not
production. It adds a layer that isn't needed and in HA, simple should trump
all else.
Yeah well, it's not really going to change for us, we are virtualised and I
can't really see that changing. In fact I would presume you would see more of
it.
Thanks
Then ensure that each VM is on a different host, otherwise the host
itself becomes a single point of failure. Further, you will want to add
a backup fence method that can take out the host if it stops responding.
Otherwise, a failure in the host would leave the target node's fence
method (the hypervisor) inaccessible, and a failed fence method can only
be handled safely by effectively hanging the cluster. It is not allowed
that no response be treated as confirmation of node death, lest you end
up with inevitable split-brains.
I do see people try to do this more often, and I will continue to
discourage it... "An HA cluster is beautiful not when there is nothing
left to add, but when there is nothing left to take away.". Every piece
in the cluster is another potential point of failure.
digimer
On 17/07/14 12:48 PM, Alex Samad - Yieldbroker wrote:
Hi
I wonder if there Best practise or how to, on how to run clusters on say
VMWare.
I have built a 2 node cluster with 2 vm's I am hesitant to give rights to each
machine to restart the other node. Plus I would have to install the vmware lib
and....
So what do other people do
Quick search gives me
http://www.hastexo.com/resources/hints-and-kinks/fencing-vmware-
virtualized-pacemaker-nodes << But I am not keen on doing that ..
I am working on centos 6.5
Can I use a network resource to make quorum, ie Can the node can ping
the dgw ?
Thanks
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Digimer
Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is
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_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
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Project Home: http://www.clusterlabs.org Getting started:
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Bugs: http://bugs.clusterlabs.org
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://bugs.clusterlabs.org
--
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?
_______________________________________________
Pacemaker mailing list: Pacemaker@oss.clusterlabs.org
http://oss.clusterlabs.org/mailman/listinfo/pacemaker
Project Home: http://www.clusterlabs.org
Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
Bugs: http://bugs.clusterlabs.org
