[Pacemaker] OCF Resource agent promote question

[Andreas Kurz]

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,
Andreas

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> 
> 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
> 
> STEVE
> 
> 
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