[Pacemaker] [RFC] Automatic nodelist synchronization between corosync and pacemaker

[Andrew Beekhof]

On Mon, Feb 18, 2013 at 6:18 PM, Vladislav Bogdanov
<bubble at hoster-ok.com> wrote:
> Hi Andrew, all,
>
> I had an idea last night, that it may be worth implementing
> fully-dynamic cluster resize support in pacemaker,

We already support nodes being added on the fly.  As soon as they show
up in the membership we add them to the cib.
For node removal we do require crm_node --remove.

Is this not sufficient?

> utilizing
> possibilities CMAP and votequorum provide.
>
> Idea is to:
> * Do not add nodes from nodelist to CIB if their join-count in cmap is
> zero (but do not touch CIB nodes which exist in a nodelist and have zero
> join-count in cmap).
> * Install watches on a cmap nodelist.node and
> runtime.totem.pg.mrp.srp.members subtrees (cmap_track_add).
> * Add missing nodes to CIB as soon as they are both
> ** defined in a nodelist
> ** their join count becomes non-zero.
> * Remove nodes from CIB when they are removed from a nodelist.

>From _a_ nodelist or _the_ (optional) corosync nodelist?

Because removing a node from the cluster because it shut down is... an
interesting idea.

> Certainly, this requires some CMAP values (especially votequorum ones
> and may be totem mode) to have some 'well-known' values, f.e. only UDPU
> mode and quorum.allow_downscale=1, that should be defined yet.
>
> May be, it also have sense to make this depend on some new CMAP
> variable, f.e. nodelist.dynamic=1.
>
> I would even try to implement this if general agreement is gained and
> nobody else wants to implement this.
>
> Can you please comment on this?
>
> Vladislav
>
> _______________________________________________
> Pacemaker mailing list: Pacemaker at 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