[Pacemaker] Dependency Loop Errors in Log

Tim Serong tserong at suse.com
Wed Aug 10 00:04:54 EDT 2011

On 09/08/11 02:36, Bobbie Lind wrote:
> I have 6 servers with three sets of 2 failover pairs. So 2 servers for
> one pair, 2 servers for another pair etc.  I am trying to configure this
> under one pacemaker instance.
> I changed from using Resource groups because the resources are not
> dependent on each other, just located together.
> I have 4 dummy resources that are used to help with colocation.
> The following configuration works as designed when I first start up
> pacemaker but when I try and run failover tests that's when things get
> screwy.
> Here is the relevant snippet of my configuration that shows the location
> and colocation set up.  As well as what I *think* I am asking it to do.
> [...snip...]
> ** Ensuring that the resources from one failover node do not start up on
> the other nodes giving -500 points.
> ** failover pairs are MDSgroup, OSS1/OSS3, and OSS2/OSS4
> colocation colocMDSOSS1 -500: anchorOSS1 MDSgroup
> colocation colocMDSOSS2 -500: anchorOSS2 MDSgroup
> colocation colocMDSOSS3 -500: anchorOSS3 MDSgroup
> colocation colocMDSOSS4 -500: anchorOSS4 MDSgroup
> colocation colocOSS1MDS -500: MDSgroup anchorOSS1
> colocation colocOSS2MDS -500: MDSgroup anchorOSS2
> colocation colocOSS3MDS -500: MDSgroup anchorOSS3
> colocation colocOSS4MDS -500: MDSgroup anchorOSS4
> colocation colocOSS2OSS1 -500: anchorOSS1 anchorOSS2
> colocation colocOSS4OSS1 -500: anchorOSS1 anchorOSS4
> colocation colocOSS1OSS2 -500: anchorOSS2 anchorOSS1
> colocation colocOSS3OSS2 -500: anchorOSS2 anchorOSS3
> colocation colocOSS2OSS3 -500: anchorOSS3 anchorOSS2
> colocation colocOSS4OSS3 -500: anchorOSS3 anchorOSS4
> colocation colocOSS1OSS4 -500: anchorOSS4 anchorOSS1
> colocation colocOSS3OSS4 -500: anchorOSS4 anchorOSS3
> [...snip...]
> One of the issues I am running into is the logs are giving me dependency
> loop errors.  Here is a snippet but it does this for all the
> anchor/dummy resources and the LVM resource(from MDSgroup)
> Aug 08 11:05:56 s02ns070 pengine: [32677]: info: rsc_merge_weights:
> anchorOSS1: Breaking dependency loop at MDSgroup
> [...snip...]
> I think these dependency loops are what's causing the other quirky
> behavior I have of resources failing to the wrong server.
> I'm not sure where the dependency loop is coming from, but I'm sure it
> has something to do with my configuration and score setup.
> Any help deciphering this would be greatly appreciated.

You can't have bidirectional colocation, i.e.. either specify 
"colocation colocMDSOSS1 -500: anchorOSS1 MDSgroup" or "colocation 
colocOSS1MDS -500: MDSgroup anchorOSS1", but not both.  The dependency 
loop error means pacemaker is tossing one of these away.  For some more 
detail check the Resource Constraints chapter of Pacemaker explained 
or the mailing list archives (this has come up a few times in recent 


Tim Serong
Senior Clustering Engineer
tserong at suse.com

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