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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.

> 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
>>
>>
>>
>>