[Pacemaker] OCF Resource agent promote question

Andreas Kurz andreas at hastexo.com
Mon Mar 25 19:01:53 EDT 2013

Hi Steve,

On 2013-03-25 18:44, Steven Bambling wrote:
> All,
> I'm trying to work on a OCF resource agent that uses postgresql
> streaming replication.  I'm running into a few issues that I hope might
> be answered or at least some pointers given to steer me in the right
> direction.

Why are you not using the existing pgsql RA? It is capable of doing
synchronous and asynchronous replication and it is known to work fine.

Best regards,

Need help with Pacemaker?

> 1.  A quick way of obtaining a list of "Online" nodes in the cluster
> that a resource will be able to migrate to.  I've accomplished it with
> some grep and see but its not pretty or fast.
> # time pcs status | grep Online | sed -e "s/.*\[\(.*\)\]/\1/" | sed 's/ //'
> p1.example.net <http://p1.example.net> p2.example.net
> <http://p2.example.net>
> real0m2.797s
> user0m0.084s
> sys0m0.024s
> Once I get a list of active/online nodes in the cluster my thinking was
> to use PSQL to get the current xlog location and lag or each of the
> remaining nodes and compare them.  If the node has a greater log
> position and/or less lag it will be given a greater master preference.  
> 2.  How to force a monitor/probe before a promote is run on ALL nodes to
> make sure that the master preference is up to date before
> migrating/failing over the resource.
> - I was thinking that maybe during the promote call it could get the log
> location and lag from each of the nodes via an psql call ( like above)
> and then force the resource to a specific node.  Is there a way to do
> this and does it sound like a sane idea ?
> The start of my RA is located here suggestions and comments 100%
> welcome https://github.com/smbambling/pgsqlsr/blob/master/pgsqlsr
> v/r
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