[ClusterLabs] Question about STONITH for VM HA cluster in shared hosts environment

[Andrés Pozo Muñoz]

Hi all,

I am a newbie to Pacemaker and I can't find the perfect solution for my
problem (probably I'm missing something), maybe someone can give me some
hint :)

My scenario is the following: I want to make a HA cluster composed of 2
virtual machines running on top of SHARED virtualization hosts. That is, I
have a bunch of hosts running multiple VMs, and I would like to create an
HA cluster with 2 VMs (Ubuntus running some app) running in (different)
hosts.

About the resources, I have no problem, I'll configure some VIP and some
lsb services in a group.

My concern is about the STONITH, I can't find the perfect config:
    * If I disable STONITH I may have the split brain problem.
    * If I enable STONITH with external/libvirt fence, I'll have a single
point of failure  if the host with the Active VM dies, right?  (Imagine the
host running that active VMs dies, the STONITH operation from the other VM
will fail and the switch-over will not happen, right?)
    * I can't use a 'hardware' (ILO/DRAC) fence, because the host is
running a lot of VMs, not only the ones in HA cluster :( I can't reboot it
because of some failure in our HA.

Is there an optimal configuration for such scenario?

I think I'd rather live with the split brain problem, but I just want to
know if I missed any config option.

Thanks in advance!

Cheers,
Andrés
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