[Pacemaker] Pacemaker multi node configuration

Mon Oct 10 08:17:37 UTC 2011

Hello Andreas, you are 100% right about leaving an idle node instead of
balancing all the VM
Among all the four nodes. But the choice was to have and idle node that can
guest all the
VMs running the core business applications in the three production nodes. So
even if all three
Production nodes will go down all the core business applications will keep
on running.
Of course, when I will have clarified exactly how to setup the node in case
of fault I
Can try some different locations in case of fault.

I hope you don't mind having a look at the attached doc. I followed the
configuration 
found in "HA virtualization with KVM -ISCSI - Pacemaker" by Florian Hass,
adding few 
lines in order to have the VM running only in the production node and if it
will fail 
will keep on running on the backup node. As I have read, that all the nodes
must to be active,
my doubt is that the same VM will try start on two nodes at the same time.

Please let me know if the attached configuration can work or there is
something missing.

Thank you so much for helping me.

My best regards.

Luciano

-----Original Message-----
From: Andreas Kurz [mailto:andreas at hastexo.com] 
Sent: sabato 8 ottobre 2011 0.44
To: pacemaker at oss.clusterlabs.org
Subject: Re: [Pacemaker] Pacemaker multi node configuration

Hello,

On 10/05/2011 03:38 PM, Luciano Sitzia wrote:
> Hello Nick, I have already read this tutorial and for two node
configuration
> is quite clear
> but I didn't get how to setup four primary nodes switching to the same
> secondary if one of 
> them will fail.

First a  question: Why would you want one node being completely idle
while it could run VMs and help decreasing per node load?

One solution I could think of for a such a dedicated cold standby server:

* for every VM resource set a score e.g. 100 for one preferred node out
of the four servers

* set a lower score e.g. 10 for every VM for the cold standby server

... on node failure (one of "the four"), the first destination for its
VMs will be the standby node as it has the next best score. The question
is what should happen on multi node failures .... or do you plan to not
let them happen? ;-)

For such a scenario I'd recommend having a look at the utilization
feature of pacemaker 1.1 in combination with different priorities for
your vms.

Regards,
Andreas

-- 
Need help with Pacemaker?
http://www.hastexo.com/now

> Do you have a tutorial/example where this situation is explained.
> 
> Thank you again.
> 
> My  best regards.
> 
> Luciano
> 
> -----Original Message-----
> From: Nick Khamis [mailto:symack at gmail.com] 
> Sent: mercoledì 5 ottobre 2011 14.45
> To: The Pacemaker cluster resource manager
> Subject: Re: [Pacemaker] Pacemaker multi node configuration
> 
> The DRBD site has a nice tutorial on Pacemaker + KVM. The rest of the
> example
> cover Xen etc...
> 
>
http://www.linbit.com/en/education/tech-guides/highly-available-virtualizati
> on-with-kvm-iscsi-pacemaker/
> 
> Nick.
> 
> On Wed, Oct 5, 2011 at 8:31 AM, Luciano Sitzia
> <l.sitzia at lsinformatica.net> wrote:
>> Hello, I read pacemaker from scratch and pacemaker explained and I
> succeeded
>> in setting Active/passive clusters between two
>>
>> Node. Now I have to configure a cluster shared failover where four
servers
>> are running KVM with all VM on  the shared storage
>>
>> SAN with GFS2 , one more server acts as KVM failover. I tried to realize
> how
>> to configure it but I got totally lost.
>>
>> Can you help me sending  me a sample configuration to understand what I
>> should do.
>>
>>
>>
>> Thanks in advance my best regards.
>>
>>
>>
>> Luciano
>>
>>
>>
>> Luciano Sitzia
>>
>> Via Palazzi, 8/G
>>
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