[Openstack-operators] Passing entire disks to instances

Steve Gordon sgordon at redhat.com
Sun Aug 30 14:53:40 UTC 2015

----- Original Message -----
> From: "David Arroyo" <droyo at aqwari.net>
> To: openstack-operators at lists.openstack.org
> Hello,
> I would like to pass entire disks to my openstack instances. I have
> some IO-bound workloads and would like to avoid any overhead or
> contention by giving an instance access to N additional disks, such
> that they do not share that disk with other guests on the same compute
> node.
> These additional disks do not need to last longer than the instances
> themselves; they are "ephemeral" in that regard. There is no need for
> backup, no need for instance or data migration, and no need for running
> the instance on a separate compute node from the extra disks.
> Effectively I want to have an "extra disks" property, as part of a
> flavor or image, that is handled like vcpus without overcommit.
> I have been doing some research but have not yet found an obvious way
> to do this in openstack. Does anyone else have a similar use case, and
> how have you handled it? To be more specific, we run some very large
> Cassandra clusters on physical hardware, with excellent performance.
> Cassandra is largely IO-bound, and we want to virtualize it without
> introducing unnecessary IO latency.
> Cheers,
> David

Have you looked at the BlockDeviceDriver as described here:



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