[rhos-list] Parallel Cinder access?

[Giulio Fidente]

On 09/03/2013 06:03 PM, Lutz Christoph wrote:
> Hi!
>
> I can't google up any good answer for the question if it is possible to
> have multiple Cinder  Volume instances access the same underlying
> storage (especially interesting is plain old LVM).
>
> The idea is to run Cinder Volume on the compute nodes and eliminate one
> trip over the network for iSCSI storage. So the Cinder Volume instances
> need to see the same volumes, and some central Cinder service
> (scheduler? API?) has to know that each compute node has its own local
> Cinder Volume service. The next step would of course be to eliminate the
> iSCSI export/import of the volume as it can be accessed through /dev/mapper.
>
> Since I haven't found any reference to this kind of architecture, I
> presume that it isn't viable (yet?). But then I would very much
> appreciate a "No. Won't work." from this list to convince some people
> around here.

you can actually deploy multiple instances of the cinder-volume service, 
on different nodes, controlled by a single cinder-{api,scheduler}

I wrote a small blog post[1] about how to setup such a topology. I would 
void the use of the local compute disks for cinder-volume though, as 
that will consume your CPU for the disks I/O. You can attach some 
external storage to each compute node instead (and maybe in that case 
even use a specific cinder driver rather than lvm).

1. 
http://giuliofidente.com/2013/04/openstack-cinder-add-more-volume-nodes.html
-- 
Giulio Fidente
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