codehaus


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Active-Active Cinder + RBD driver + Co-ordination


On 05/02, Paul Browne wrote:
> Hi list,
>
> I had a quick question about Active-Active in cinder-volume and
> cinder-backup stable/stein and RBD driver, if anyone can help.
>
> Using only the Ceph RBD driver for volume backends, is it required to run
> A-A cinder services with clustering configuration so that they form a
> cluster?
>
> And, if so, is an external coordinator (redis/etcd/Consul) necessary,
> again only using RBD driver?
>

Hi,

For the time being the cluster concept only applies to the cinder-volume
service.  The cinder-backup service has 2 modes of operation: only
backup from current node (so we can have different backup drivers on
each node) deployed as A/P, and backup from any node (then all drivers
must be the same) deployed as A/A.

When deploying cinder-volume as active-active a coordinator is required
to perform the functions of a DLM to respect mutual exclusion sections
across the whole cluster.

Drivers that can be used for the coordination are those available in
Tooz [1] that support locks (afaik they all support them).

If you don't form a cluster and deploy all cinder-volume services in A/A
sharing the same host you'll end up in a world of pain, among other
things, as soon as you add a new node or a cinder-volume service is
restarted, as it will disturb all ongoing operations from the other
cinder-volume services.

I hope this helps.

Cheers,
Gorka.


[1]: https://docs.openstack.org/tooz/latest/user/drivers.html


> Best docs I could find on this so far were;
>
> https://docs.openstack.org/cinder/latest/contributor/high_availability.html
> ,
>
> I support more aimed at devs/contributoers than operators, but it's not
> 100% clear to me on these questions
>
> Thanks,
> Paul
>
> --
> *******************
> Paul Browne
> Research Computing Platforms
> University Information Services
> Roger Needham Building
> JJ Thompson Avenue
> University of Cambridge
> Cambridge
> United Kingdom
> E-Mail: pfb29 at cam.ac.uk
> Tel: 0044-1223-746548
> *******************