[Linux-HA] Trying to understand sets

RaSca rasca at miamammausalinux.org
Fri Oct 1 02:24:09 MDT 2010


Hi all,
as discussed two days ago on IRC, since that the 1.0.9 version had some 
problems with multistate resources and groups, I'm trying to make sets work.
I started from this configuration:

group cluster cluster-fs cluster-jboss
ms cluster-ms-r0 cluster-r0 \
	meta master-max="1" master-node-max="1" clone-max="2" 
clone-node-max="1" notify="true"
colocation cluster_on_cluster-r0 inf: cluster cluster-ms-r0:Master
order cluster_after_cluster-r0 inf: cluster-ms-r0:promote cluster-fs:start

But, as i said, there's a bug in this version of Pacemaker, so the 
solution is to treat every single resource. Thanks to the IRC guys match 
and andreask I find out a solution using sets, in this way:

ms cluster-ms-r0 cluster-r0 \
	meta master-max="1" master-node-max="1" clone-max="2" 
clone-node-max="1" notify="true"
colocation cluster-fs_on_cluster-r0 inf: ( cluster-jboss ) ( cluster-fs 
) cluster-ms-r0:Master
order cluster-fs_after_cluster-r0 inf: cluster-ms-r0:promote ( 
cluster-fs:start ) ( cluster-jboss:start )

Everything works fine. But I have two questions:

1) what's the difference between the declaration with sets that is over 
there and this one:

ms cluster-ms-r0 cluster-r0 \
	meta master-max="1" master-node-max="1" clone-max="2" 
clone-node-max="1" notify="true"
colocation cluster-fs_on_cluster-r0 inf: cluster-jboss cluster-fs 
cluster-ms-r0:Master
order cluster-fs_after_cluster-r0 inf: cluster-ms-r0:promote 
cluster-fs:start cluster-jboss:start

In this way the resources comes up all the same time? Note: this does 
not worked for me, of course.

2) Using sets it is also possible to declare groups just for logical 
purpose (and for the output of crm_mon), without using them in 
colocation and order declaration? Does the creation of a group make some 
changes in the resources relations?

Thanks a lot!

-- 
RaSca
Mia Mamma Usa Linux: Niente è impossibile da capire, se lo spieghi bene!
rasca at miamammausalinux.org
http://www.miamammausalinux.org



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