Open Stack

Thank you much.
I try to understand it. I will feedback if I can do something,
Nguyen Huu Khoi


On Thu, Jul 13, 2023 at 6:45 PM Gorka Eguileor <geguileo at redhat.com> wrote:

> On 13/07, Nguyễn Hữu Khôi wrote:
> > hello.
> > Thank you for your valuable information, I got this problem.
> > Can you help me see how nova will be updated? I ask about something
> which I
> > can touch or modify at nova manually,
> >
> > Nguyen Huu Khoi
> >
>
> Hi,
>
> This is not something that can be easily fixed in the OpenStack code.
>
> There's always the manual hacking mechanism of changing things manually
> in libvirt using virsh without Nova knowing about it.  I don't know the
> exact commands to run because I work on Cinder, but it's probably
> related to this old spec [1].
>
> Making the code changes in OpenStack is non trivial, as it would
> require:
>
> - Add a new external event type to the Nova code to change the QoS for
>   an instance.
>
> - Changing Cinder to do the following when QoS is updated:
>
>     - Check volume types that use the updated QoS
>     - Check volumes using those volume types
>     - Check which volumes are connected to instances
>     - For each of those volumes:
>       - Update the connection information in the DB
>       - Call Nova with the new external event type to update the
>         instance.
>       - If it's multi attached it may require making multiple calls
>         for the same volume.
>
> Cheers,
> Gorka.
>
> [1]:
> https://specs.openstack.org/openstack/nova-specs/specs/rocky/implemented/enhanced-kvm-storage-qos.html
>
> >
> > On Thu, Jul 13, 2023 at 5:10 PM Gorka Eguileor <geguileo at redhat.com>
> wrote:
> >
> > > 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.
> > >
> > >
> > >
>
>
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