[DRBD-user] Can't Get DRBD Master/Slave out of secondary/secondary using pacemaker

Florian Haas f.g.haas at gmx.net
Fri Sep 23 22:28:30 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 2011-09-23 22:24, Arnold Krille wrote:
> On Friday 23 September 2011 21:23:55 Florian Haas wrote:
>> On 2011-09-23 19:06, Arnold Krille wrote:
>>> On Friday 23 September 2011 17:54:26 Florian Haas wrote:
>>>> On 2011-09-23 14:58, Nick Khamis wrote:
>>>>> colocation mysql_on_drbd \
>>>>> 	inf: ms_drbd_mysql:Master HAServices
>>>> Incorrect; should be "colocation mysql_on_drbd inf: HAServices
>>>> ms_drbd_mysql:Master"
>>> As far as I understand both the docs and my practical experience, the
>>> order of elements in the colocation is irrelevant.
>> Not trying to challenge your experience or your understanding of the
>> documentation, but the idea that colocation constraints are
>> non-directional is simply a wrong assumption.
>> http://www.clusterlabs.org/mwiki/images/6/61/Colocation_Explained.pdf
>> Slide 2.
> Challenge accepted:) I will check my experience next week, the cluster 
> concerned isn't yet in productional use.

Swap them around and stop or fail resources. Then it becomes evident
fairly quickly.

>>> The order in groups or in order-statements however is not.
>> For a group, that is of course unless is has meta ordered=false.
> Unordered groups inside ordered groups are something I have to get my head 
> around too. But probably my cluster definitions will be more complex than 
> "simple" groups inside groups because for two machines there is the chain of 
> drbd-ms->gfs->mount->libvirt, for the (not yet realized) extensions it will be 
> iscsi->gfs->mount->libvirt. And the prerequisite for virtual machine should 
> only be "libvirt"...

You can't do nested groups. Pacemaker groups can only ever contain
primitives. Resource sets are a different story. I _think_ you can
actually put a group in a resource set, but that would be making things
overly complicated on purpose.


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