Open Stack

On 22/09, Eugen Block wrote:
> Hi,
>
> thanks for the clarification.
> We don't set "backend_host" at all at the moment, only "host" to the virtual
> hostname which has the virtual IP assigned by pacemaker. This seems to work
> fine.

Hi,

I assume than in an Active-Active deployment you won't be using
pacemaker, and in that case I would not define "host" at all.

Cheers,
Gorka.

>
> > Changing a deployment from Active-Passive to Active-Active is a bit
> > trickier, because you need to leave one of the cinder-volume services
> > running (at least once) with the old `backend_host` so it can "move"
> > resources (volumes/snapshots) to the "cluster".
>
> I'm not sure if we'll even try that, I was thinking more about new
> deployments that would be using active/active from the beginning. If we
> decided to switch we'd test it heavily before chaning anything. ;-)
>
> Thanks again!
> Eugen
>
> Zitat von Gorka Eguileor <geguileo at redhat.com>:
>
> > On 31/08, Eugen Block wrote:
> > > I think I found my answers. Currently I only have a single-control node in
> > > my test lab but I'll redeploy it with three control nodes and test it with
> > > zookeeper. With a single control node the zookeeper and cinder cluster
> > > config seem to work.
> > >
> >
> > Hi Eugen,
> >
> > Besides deploying the DLM, configuring it in Cinder, and setting the
> > `cluser` configuration option you should also be careful with the
> > `host`/`backend_host` configuration option.
> >
> > In Active-Passive deployments we set the `backend_host` configuration
> > option so it is preserved when cinder-volume fails over to a different
> > controller host, but in Active-Active we actually want each host to have
> > cinder-volume running with different values, so we usually leave it
> > unset so it takes the controller's host name.
> >
> > Changing a deployment from Active-Passive to Active-Active is a bit
> > trickier, because you need to leave one of the cinder-volume services
> > running (at least once) with the old `backend_host` so it can "move"
> > resources (volumes/snapshots) to the "cluster".
> >
> > Cheers,
> > Gorka.
> >
> > > Zitat von Eugen Block <eblock at nde.ag>:
> > >
> > > > Hi,
> > > >
> > > > I didn't mean to hijack the other thread so I'll start a new one.
> > > > There are some pages I found incl. Gorkas article [1], but I don't
> > > > really understand yet how to configure it.
> > > >
> > > > We don't use any of the automated deployments (we created our own) like
> > > > TripleO etc., is there any guide showing how to setup cinder-volume
> > > > active/active? I see in my lab environment that python3-tooz is already
> > > > installed on the control node, but how do I use it? Besides the
> > > > "cluster" config option in the cinder.conf (is that defined when setting
> > > > up the DLM?) what else is required? I also found this thread [2]
> > > > pointing to the source code, but that doesn't really help me at this
> > > > point. Any pointers to a how-to or deployment guide would be highly
> > > > appreciated!
> > > >
> > > > Thanks,
> > > > Eugen
> > > >
> > > > [1] https://gorka.eguileor.com/a-cinder-road-to-activeactive-ha/
> > > > [2]
> > > https://www.mail-archive.com/openstack@lists.openstack.org/msg18385.html
> > >
> > >
> > >
> > >
>
>
>