Open Stack

> If we end up using a DLM then we have to detect when the connection to
> the DLM is lost on a node and stop all ongoing operations to prevent
> data corruption.
> 
> It may not be trivial to do, but we will have to do it in any solution
> we use, even on my last proposal that only uses the DB in Volume Manager
> we would still need to stop all operations if we lose connection to the
> DB.

Well, is it already decided that Pacemaker would be chosen to provide HA in 
Openstack? There's been a talk "Pacemaker: the PID 1 of Openstack" IIRC.

I know that Pacemaker's been pushed aside in an earlier ML post, but IMO 
there's already *so much* been done for HA in Pacemaker that Openstack 
should just use it.

All HA nodes needs to participate in a Pacemaker cluster - and if one node 
looses connection, all services will get stopped automatically (by 
Pacemaker) - or the node gets fenced.


No need to invent some sloppy scripts to do exactly the tasks (badly!) that 
the Linux HA Stack has been providing for quite a few years.


Yes, Pacemaker needs learning - but not more than any other involved 
project, and there are already quite a few here, which have to be known to 
any operator or developer already.


(BTW, LINBIT sells training for the Linux HA Cluster Stack - and yes,
 I work for them ;)