[Pacemaker] How to stop a resource?

Tim Ward Tim.Ward at ipaccess.com
Thu Mar 15 09:47:06 EDT 2012

> From: Andreas Kurz [mailto:andreas at hastexo.com] 
> >>
> >> Maybe totally in the wrong direction for what you want but...
> >> Put commands in a script and add a until loop with a pgrep 
> test and 
> >> sleep 1 till the specific resource is stopped then continue?
> > 
> > Yes, probably is in the wrong direction. I'm driving this 
> from Java and have written an interface to the "crm" command, 
> which is how I was advised to get at Pacemaker from Java when 
> I enquired on this list.
> I think your problem is, that a "crm resource stop" is 
> asynchronous ...
> it exits immediately, not waiting for the resource to stop eventually.

Is that what's happening? It's not what I expected from the documentation I was able to find.

> How about looping on "crm resource status _resource_" before deleting?

Clearly this is possible, but I'd have a few issues to sort out

- I'd have to write some code to parse the output of the status command, and hope that the syntax of this output doesn't change in future versions - or are there defined return strings or codes that I can guarantee to be able to rely on?

- I hate polling - it's just burning CPU cycles to no useful purpose, and whenever I see either polling or a "sleep" I suspect the design[#]

- this won't work for a resource killing itself, as it won't get a chance to do the delete as it won't still be there, whereas it *is* possible for a resource to kill itself it it throws everything at the crm command in one go

[#] Yes yes, I know I can write an SNMP trap receiver and avoid the polling that way. It's fairly low down my list of options though.

Tim Ward
Brett Ward Limited - www.brettward.co.uk  

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