[Linux-HA] Is this the right config?

[Andrew Beekhof]

On 10/1/07, Kelly Byrd <kbyrd-linuxha at memcpy.com> wrote:
>
> >> I have a drbd master/slave resource (ms-drbd1), and then a group
> >> (group_vm1). The group contains and filesystem resource (vm1-fs) and my
> >> VM
> >> (vm1-vm) resource. I have an rsc_order contraint saying group_vm1 should
> >> only run where ms-drbd1 has been promoted. I also have a rsc_colocation
> >> constraint saying group_vm1 follows ms-drbd1.
> >
> > You mean the other way around: exchange rsc_order and
> > rsc_colocation.
> >
>
> I used this XML from the howto page:
> <rsc_order id="drbd0_before_fs0" from="fs0" action="start" to="ms-drbd0"
> to_action="promote"/>
> <rsc_colocation id="fs0_on_drbd0" to="ms-drbd0" to_role="master"
> from="fs0" score="infinity"/>
>
>
> >> Finally I have a location
> >> constaint saying ms-drbd1 prefers node1.
> >>
> >> When testing this with two VMs (add ms-drbd2 and group_vm2, prefering
> >> node2), things don't always work out as planned. Sometimes, with only
> >> one
> >> node running, if I "/etc/init.d/heartbeat start" on node1, ms-drbd1 and
> >> group_vm1 will try to migrate over to node1, fail then return back to
> >> node2. It's not clear to me what's failing.
> >
> > What do the logs say?
> >
>
> >> Should I be grouping these differently?
> >
> > The config looks ok to me.
> >
>
> I have the impression that I can't put the master/slave drbd resource in
> the group with the other two, because it's master/slave-ness isn't the
> same as the other two start/stop resources. Is this true?

groups can not contain clones or master/slave resources (which are
just a special kind of clone)

you can however clone a group

> Basically, I'm looking for how to scale this out easily without a ton of
> XML entries for the 22 things I'm managing.

it depends what is scaling up... the number of m/s or the number of
items that need to run on the master