Hi
On Wed, 23 Sep 2009 10:53:51 +0200
Dejan Muhamedagic <[email protected]> wrote:
> The order constraint means: if resource A is not running then
> resource B can't run either. So, in order to stop A, you have to
> stop B first. Though there are non-symmetrical constraints in
> which stop order is not required to be the opposite of the start
> order.
Ok, i got the idea. So, actually i've expected exactly this behaviour,
but only for start/stop operations.
> So, if this is not what you want/expect, perhaps you don't need
> an order constraint. Can you describe the resources and how they
> depend on each other.
I have two nodes (n1,n2) with two XEN resources configred on them,
let call them A and B. The B resource is a virtual machine, running
webserver and stuff. The A resrouce as a virtual machine, running a
MySQL server. Web on the B vm requires mysql on the A vm. Therefore, to
ensure that resources are started in proper order, i've created a order
constraint:
"First A then B".
So my cluster is working good, resource A is running on n1, resource B
on n2. For some reason i decide to make
some maintenance on node n1 and tell the crm to set that node to
'standby' state. During the next several seconds i see the following
actions:
The B resource is stopped on n2 node
The A resource is migrated to n2 node
The B resource is started on n2 node
I was expecting that B resource wouldn't be touched at all. The A
resource was unavailable for less then a second and it didn't
rebooted and it's execution state doesn't changed during migration.
--
Denis Chapligin
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