Mailing List Archive: colocate three resources

colocate three resources

Nov 9, 2014, 2:28 AM

Post #1 of 3 (827 views)

Hallo,

On a cluster I have to place three resources on the same node.

ms ms_disk_R p_disk_R
ms ms_disk_S p_disk_S
primitive vm_srv ocf:heartbeat:VirtualDomain

The colocation constraints looks like this:

colocation vm_with_disk_R inf: vm_srv ms_disk_R:Master
colocation vm_with_disk_S inf: vm_srv ms_disk_S:Master

Do I have to add another colocation constraint to define a
colocation between disk_R and disk_S. I'm not sure because the
documentation says:

"with-rsc: The colocation target. The cluster will decide where to
put this resource first and then decide where to put the resource in
the rsc field."

In my case the colocation targets are "ms_disk_R" and "ms_disk_S".
If pacemaker decides to put disk_R on node A and disk_S on node B
vm_srv would not start.

I use order constraints to start disks before the vm resource.

order disk_R_before_vm inf: ms_disk_R:promote vm_srv:start
order disk_S_before_vm inf: ms_disk_S:promote vm_srv:start

Thanks
Matthias

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Re: colocate three resources [ In reply to ]

alxgomz at gmail

Nov 9, 2014, 2:51 AM

Post #2 of 3 (805 views)

Permalink

I think you can use a single colocation with a set of resources. crmsh
allows you to create such a colocation with:

crm colocation vm_with_disks inf: vm_srv ( ms_disk_R:Master
ms_disk_S:Master )

This forces the cluster to place the master resources on the same host,
starting them without specific ordering, and then start the VM along with
them.
Le 9 nov. 2014 11:31, "Matthias Teege" <matthias-gmane@mteege.de> a Ã©crit :

> Hallo,
>
> On a cluster I have to place three resources on the same node.
>
> ms ms_disk_R p_disk_R
> ms ms_disk_S p_disk_S
> primitive vm_srv ocf:heartbeat:VirtualDomain
>
> The colocation constraints looks like this:
>
> colocation vm_with_disk_R inf: vm_srv ms_disk_R:Master
> colocation vm_with_disk_S inf: vm_srv ms_disk_S:Master
>
> Do I have to add another colocation constraint to define a
> colocation between disk_R and disk_S. I'm not sure because the
> documentation says:
>
> "with-rsc: The colocation target. The cluster will decide where to
> put this resource first and then decide where to put the resource in
> the rsc field."
>
> In my case the colocation targets are "ms_disk_R" and "ms_disk_S".
> If pacemaker decides to put disk_R on node A and disk_S on node B
> vm_srv would not start.
>
> I use order constraints to start disks before the vm resource.
>
> order disk_R_before_vm inf: ms_disk_R:promote vm_srv:start
> order disk_S_before_vm inf: ms_disk_S:promote vm_srv:start
>
> Thanks
> Matthias
>
>
> _______________________________________________
> 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
>

Re: colocate three resources [ In reply to ]

andrew at beekhof

Nov 9, 2014, 7:26 PM

Post #3 of 3 (801 views)

Permalink

> On 9 Nov 2014, at 9:28 pm, Matthias Teege <matthias-gmane@mteege.de> wrote:
>
> Hallo,
>
> On a cluster I have to place three resources on the same node.
>
> ms ms_disk_R p_disk_R
> ms ms_disk_S p_disk_S
> primitive vm_srv ocf:heartbeat:VirtualDomain
>
> The colocation constraints looks like this:
>
> colocation vm_with_disk_R inf: vm_srv ms_disk_R:Master
> colocation vm_with_disk_S inf: vm_srv ms_disk_S:Master
>
> Do I have to add another colocation constraint to define a
> colocation between disk_R and disk_S. I'm not sure because the
> documentation says:
>
> "with-rsc: The colocation target. The cluster will decide where to
> put this resource first and then decide where to put the resource in
> the rsc field."
>
> In my case the colocation targets are "ms_disk_R" and "ms_disk_S".
> If pacemaker decides to put disk_R on node A and disk_S on node B
> vm_srv would not start.

Correct, this is why you need the third constraint - as smart as pacemaker is, its nowhere as good as a human brain.
So while it is obvious to us that "ms_disk_R" and "ms_disk_S" need to go on the same node, pacemaker will need the extra hint.

Suggestion, do this:

colocation disk_S_with_disk_R inf: ms_disk_S:Master ms_disk_R:Master
colocation vm_with_disk_S inf: vm_srv ms_disk_S:Master

For ordering you want as much parallelism as possible, for colocation - chains work best.

>
> I use order constraints to start disks before the vm resource.
>
> order disk_R_before_vm inf: ms_disk_R:promote vm_srv:start
> order disk_S_before_vm inf: ms_disk_S:promote vm_srv:start
>
> Thanks
> Matthias
>
>
> _______________________________________________
> 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

_______________________________________________
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