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

Arne Wiebalck Arne.Wiebalck at cern.ch
Thu Jan 8 10:14:26 UTC 2015


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
CERN IT


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