On 04/08/15 10:50 +0200, Philipp Marek wrote:
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 ;)
With all due respect, because I know you come with the best of intentions but, how is the above related to *anything* in this thread? Hasn't this thread digressed enough to throw pacemaker in the discussion just for the sake of it? I don't mean to come off harsh but seriously, let's stop trying to save the world in one thread and, instead, let's try to focus on what the real problem that is being solved is and how we can do it. The "to DLM or not" discussion was moved to a new thread (renamed from this one) and this one should be used to discussed *cinder specific issues* and hopefully come up with a solution - that Gorka has already proposed - that would provide a better story for Cinder in the short future. Flavio -- @flaper87 Flavio Percoco
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