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On 27/06, Nguyễn Hữu Khôi wrote:
> Hello guys.
> I am trying to use cinder qos.
> But i have question.
> - I added qos after a volume was create and I see that qos did not apply to
> this volume.
> - i create new volume with assosiate qos then it is ok but when i changed
> extra specs in qos, volume keep old specs.
> Is there any way to make qos apply with two above cases.
> Many thanks.

Hi,

I'm surprised you can even do it, I would expect this would be similar
to changing a volume type when there's already a volume using it, which
is not allowed.

I assume you are using 'front-end' or 'both' QoS provider, because the
situation is even worse for 'back-end' QoS providers.

For front-end qos the values will NOT be updated in Nova until a new
attachment is created, but it must be one that creates new connection
information.

Changing that would be a new feature requiring changes in Cinder and
Nova, since Cinder would need to go through all the volumes that use
volumes types associated with that QoS, check which ones are currently
attached, update their connection_information in the cinder DB, and then
report to Nova the new values (this API doesn't exist).

For back-end QoS it would be driver dependent. I assume in most cases a
retype would be necessary, but in some drivers they may be updating the
QoS on the backed for all volumes once a new volume with that volume
type or QoS is created.

Cheers,
Gorka.