[openstack-dev] [Cinder] volume / host coupling

Duncan Thomas duncan.thomas at gmail.com
Thu Jan 8 14:11:45 UTC 2015

The problem is that the scheduler doesn't currently have enough info to
know which backends are 'equivalent' and which aren't. e.g. If you have 2
ceph clusters as cinder backends, they are indistinguishable from each

On 8 January 2015 at 12:14, Arne Wiebalck <Arne.Wiebalck at cern.ch> wrote:

> Hi,
> The fact that volume requests (in particular deletions) are coupled with
> certain Cinder hosts is not ideal from an operational perspective:
> if the node has meanwhile disappeared, e.g. retired, the deletion gets
> stuck and can only be unblocked by changing the database. Some
> people apparently use the ‘host’ option in cinder.conf to make the hosts
> indistinguishable, but this creates problems in other places.
> From what I see, even for backends that would support it (such as Ceph),
> Cinder currently does not provide means to ensure that any of
> the hosts capable of performing a volume operation would be assigned the
> request in case the original/desired one is no more available,
> right?
> If that is correct, how about changing the scheduling of delete operation
> to use the same logic as create operations, that is pick any of the
> available hosts, rather than the one which created a volume in the first
> place (for backends where that is possible, of course)?
> Thanks!
>  Arne
>> Arne Wiebalck
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> OpenStack-dev at lists.openstack.org
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Duncan Thomas
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