live migration doesn't work for VMs in rescued state

[Loganathan Parthipan]

I'd expect live-migration to migrate instances in rescued state as they're online VMs anyway, as opposed to those that are shutoff or suspended. However, I see that it's currently disabled in the compute API.

nova live-migration --block-migrate b32b0eb4-b8aa-4204-b104-61e733839227 overcloud-novacompute0-aipxwbabgq7a
ERROR: Cannot 'os-migrateLive' while instance is in vm_state rescued (HTTP 409) (Request-ID: req-5eea8f1c-5602-4d48-9690-929baff3b560)

This is stopped by this decorator:

    @check_instance_state(vm_state=[vm_states.ACTIVE])
    def live_migrate(self, context, instance, block_migration,

However, there are more to it than fixing the decorator.

Should we treat this as a feature or bugfix?

[Daniel Berrange (berrange)]

For paused VMs this is certainly a bug - there's no reason to restrict this for paused VMs.

For rescued VMs, it is a little more complicated, but again the VM is "active" from the POV of the user so I'd expect migrate to be allowe & o succeed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/97797

[Loganathan Parthipan (parthipan)]

Could someone please review this patch to fix paused live-migrations?
https://review.openstack.org/#/c/97797/

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: master
Review: https://review.openstack.org/97797
Reason: this has not addressed comments in over 1.5 months, abandoning

[Sean Dague (sdague)]

Upstream patch stalled

[Matthew Gilliard (matthew-gilliard-u)]

I have agreed with Parthipan that I will continue his fix. I would like to confirm with Dan Berrange and others whether the approach taken there is still correct. Thanks.

[Davanum Srinivas (DIMS) (dims-v)]

Fix proposed again.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/97797
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=22dde6e56b2d93d9aa3776952eb7fc0792e220dc
Submitter: Jenkins
Branch: master

commit 22dde6e56b2d93d9aa3776952eb7fc0792e220dc
Author: Loganathan Parthipan <email address hidden>
Date: Mon Dec 15 14:23:18 2014 +0000

    Support live-migrate of instances in PAUSED state

    Live migration enables one to migrate an active VM that consumes
    system resources such as memory and CPU.

    Nova currently allows only those in ACTIVE vm_state to migrate. This
    patch adds support for PAUSED vm_state. Essentially a paused state is
    identical to a running state except the stopped CPUs.

    Co-Author: "Matthew Gilliard <email address hidden>"

    Partial-Bug: #1305062
    Change-Id: Ib38eaf412cb51a9cbfc443c5ec15c5797265ddae

[Bartosz Fic (bartosz-fic)]

Here is doc related to vm states and transitions:
http://docs.openstack.org/developer/nova/devref/vmstates.html

Do you think, that this change has impact on this doc ?

[Pawel Koniszewski (pawel-koniszewski)]

Matthew, do you also work on LM of VMs in rescued state?

[Matthew Gilliard (matthew-gilliard-u)]

Hi Pawel

   Yes, I expect to have a patch up for this soon (next couple of
weeks). It's a more complicated case though, sadly.

   Matthew

On 02/04/15 13:46, Pawel Koniszewski wrote:
> Matthew, do you also work on LM of VMs in rescued state?
>

[Sujitha (sujitha-neti)]

Allowing live migration for rescue state would come under feature enhancement. So I think it has to be moved to Wishlist.

[John Garbutt (johngarbutt)]

This feels like a bug fix.

[Markus Zoeller (markus_z) (mzoeller)]

After double-checking with danpb this is still a valid bug report and
it should be fixed for rescued instances.

Dear assignee, please provide a (WIP) patch in the next weeks. If you
stop working on this report, please remove yourself as assignee and
switch the status back. If you need assistance, reach out on the
IRC channel #openstack-nova or use the mailing list.

[Sean Dague (sdague)]

There are no currently open reviews on this bug, changing
the status back to the previous state and unassigning. If
there are active reviews related to this bug, please include
links in comments.

[Matt Riedemann (mriedem)]

There is a blueprint for this:

https://blueprints.launchpad.net/nova/+spec/live-migrate-rescued-instances