XenServer 6.5 fails to attach to Cinder volumes

[Bob Ball]

There is a bug when connecting to Cinder volumes over iSCSI with XenAPI where a tapdisk is not correctly spawned. This has been fixed in https://github.com/xapi-project/sm/commit/7a8a158493d03ceeb31bc8a43b7f213e74420bf0 however, users of XenServer 6.5 need a workaround in Nova.

The impact of this is that, without the fix, XAPI is expecting a tapdisk to be spawned, but the Storage Manager does not spawn one. As such, the VM will not be able to connect to this Cinder volume, and may connect to a different volume on the same host.

The correct fix in Nova is to emulate the above commit for users of XenServer 6.5; i.e. set the backend-kind=vbd. This will ensure that the storage manager spawns a tapdisk, and that it can be attached in the correct way

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/231103

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/231103
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=46c55399c04513c1e6b939be46d71036cd81c4fb
Submitter: Jenkins
Branch: master

commit 46c55399c04513c1e6b939be46d71036cd81c4fb
Author: Bob Ball <email address hidden>
Date: Tue Oct 6 11:53:44 2015 +0100

    XenAPI: Workaround for 6.5 iSCSI bug

    XenServer 6.5 doesn't handle iSCSI connections correctly, due to a bug
    introduced when changing the backend support.
    This has been fixed upstream for the next version of XenServer, but
    fix in Nova as well to ensure users of 6.5 can use Cinder-provided
    volumes

    Change-Id: I74e690228690d42e247f948e8be8e82ba1bf4c5b
    Closes-bug: 1502929

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/281341

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/kilo
Review: https://review.openstack.org/281344

[OpenStack Infra (hudson-openstack)]

Change abandoned by Bob Ball (<email address hidden>) on branch: stable/kilo
Review: https://review.openstack.org/281344
Reason: UT need some work if I'm going to cherry-pick to Kilo

[Tony Breeds (o-tony)]

@BobBall: in the description you say:

 > The impact of this is that, without the fix, XAPI is expecting a tapdisk to be spawned, but the Storage Manager does not spawn one. As such, the VM will not be able to connect to this Cinder volume, and may connect to a different volume on the same host.

Can you provide more details on which incorrect volume it will be? Different volume within the same project? or just a different volume on the host regardless of project_id?

[Bob Ball (bob-ball)]

The most likely scenario is that the volume attach will simply fail. However, there may be a rare case where the volume attached could be any volume already attached on the host (i.e. not restricted to being with the same project)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/281341
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=9fbd70660755eae95a400b03c9867fe9e7d3d335
Submitter: Jenkins
Branch: stable/liberty

commit 9fbd70660755eae95a400b03c9867fe9e7d3d335
Author: Bob Ball <email address hidden>
Date: Tue Oct 6 11:53:44 2015 +0100

    XenAPI: Workaround for 6.5 iSCSI bug

    XenServer 6.5 doesn't handle iSCSI connections correctly, due to a bug
    introduced when changing the backend support.
    This has been fixed upstream for the next version of XenServer, but
    fix in Nova as well to ensure users of 6.5 can use Cinder-provided
    volumes

    Change-Id: I74e690228690d42e247f948e8be8e82ba1bf4c5b
    Closes-bug: 1502929
    (cherry picked from commit 46c55399c04513c1e6b939be46d71036cd81c4fb)
    Depends-On: Iefa5b16a3fa1789ed583426ea47ebb22e6cb571e