[ClusterLabs] resource grouping

Kristoffer Grönlund kgronlund at suse.com
Wed Jun 10 07:35:15 EDT 2015

Dennis Jacobfeuerborn <dennisml at conversis.de> writes:

> On 10.06.2015 10:02, Kristoffer Grönlund wrote:
>> Dennis Jacobfeuerborn <dennisml at conversis.de> writes:
>>> Hi,
>>> is there a way to group resources without also adding implicit ordering?
>>> My use-case is that I want to set up a redundant NFS system that uses
>>> drbd to mirror a few volumes. These volumes are then mounted and exported.
>>> The problem is that if I have e.g. 10 Filesystem resources I currently
>>> have to both a colocation and an order constraint for *each* filesystem
>>> which is quite cumbersome and as a result also prone to errors.
>>> What I'd like to be able to do is to put all filesystem resources in a
>>> group and then only create one colocation and order contraint each
>>> between the drbd clone resource and this filesystem resource group.
>>> Since right now grouping implies ordering that is somewhat inefficient
>>> because the filesystems cannot be mounted in parallel when grouped.
>>> Is there a way to accomplish what I'm trying to do in pacemaker/pcs?
>> Yes, there is something called tags. It is like a group, but doesn't
>> imply any constraints. You can then apply constraints to the tag. See
>> http://crmsh.github.io/man/#cmdhelp_configure_tag
>> This is a new feature in pacemaker 1.1.12+.
> This looks exactly like what I am looking for but as far as I can tell
> this isn't supported in pcs and only in crmsh is that correct?

I don't know about pcs, but it's ultimately supported by pacemaker
yourself. If pcs doesn't support it, you can configure the XML directly
using cibadmin. However, installing crmsh isn't too difficult ;)

The easiest thing may be to build from source, unless you're on
SLE. It'll tell you when you run it if there's any dependency missing
that it expected to have.

> Regards,
>    Dennis

// Kristoffer Grönlund
// kgronlund at suse.com

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