target removal on detaching volume with multi-attach flag

[Chris Gacsal]

Cinder-volume removes target on detaching volume with multi-attach flag even
if the volume still has attachments.
This bug has been found during the development of volume-multi-attach support for nova.

To reproduce it in devstack:
- get multi-attach support for nova: https://review.openstack.org/#/c/153038/
- create a volume with multi-attach flag: cinder create 1 --allow-multiattach
- create two instances (host was the same for both vms in our case)
- attach volume to the instances
- check iscsi target: tgtadm --lld iscsi --mode target --op show
- check iscsi session: iscsiadm -m session -P 3
- detach the volume from one of the vms
- check iscsi target/session again

[OpenStack Infra (hudson-openstack)]

Change abandoned by Chris Gacsal (<email address hidden>) on branch: master
Review: https://review.openstack.org/198400

[Sean McGinnis (sean-mcginnis)]

A cinder detach should not be called if it is just being removed from an instance on the same host. Detach is only needed when a hypervisor host no longer needs the volume for any instances.

[Ildiko Vancsa (ildiko-vancsa)]

As multi-attach use cases are handled now on per instance basis this bug is still valid and needs to be fixed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/255595

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/266006

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/266006
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=3632173486f89d541c121be8e041a1da636edf32
Submitter: Jenkins
Branch: master

commit 3632173486f89d541c121be8e041a1da636edf32
Author: Walter A. Boring IV <email address hidden>
Date: Mon Jan 11 03:43:09 2016 -0800

    Allow host and instance_uuid at attach

    This patch removes the restriction on passing both
    host name and instance_uuid during os-attach call.

    Change-Id: I2a66920a76d3abfd6da384d2dd963f054ce61c03
    Partial-Bug: #1471278

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/256273
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d31bb4be8edbce6719258ae1cbbb583a2c3c3a28
Submitter: Jenkins
Branch: master

commit d31bb4be8edbce6719258ae1cbbb583a2c3c3a28
Author: Ildiko Vancsa <email address hidden>
Date: Thu Dec 10 21:29:11 2015 +0100

    Pass host when call attach to Cinder

    The lvm driver needs the host name information in order to be able to
    provide detach properly. This patch adds the host information to the
    attach call under virt/block_device and in volumer/cinder.

    Partial-Bug: #1471278

    Change-Id: I2c19f7a09299ceb266921f97f40354fb2ed76716

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/300684

[OpenStack Infra (hudson-openstack)]

Change abandoned by Scott DAngelo (<email address hidden>) on branch: master
Review: https://review.openstack.org/300684
Reason: We're taking a new path for fixing issues with Volume multi-attach. This is no longer needed.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean McGinnis (<email address hidden>) on branch: master
Review: https://review.openstack.org/255595
Reason: This review is > 4 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.

[Maciej Szankin (mszankin)]

This bug report has an assignee for a while now but there is no patch
for that. It looks like that the chance of getting a patch is low.
I'm going to remove the assignee to signal to others that they can take
over if they like.
If you want to work on this, please:
* add yourself as assignee AND
* set the status to "In Progress" AND
* provide a (WIP) patch within the next 2 weeks after that.
If you need assistance, reach out on the IRC channel #openstack-nova or
use the mailing list.

Also tagging as New. It is old and requires to be verified.

[Sean Dague (sdague)]

Is this still a known issue? If so, please put in the Confirmed state.

[Ildiko Vancsa (ildiko-vancsa)]

We are on our way to implement a lock mechanism on top of the built-in protection on the Cinder side not to remove targets when there are still active connections.

References:

shared_targets flag to volume details: https://review.openstack.org/#/c/509005/
multiattach spec for Nova: https://review.openstack.org/#/c/499777/

[Ildiko Vancsa (ildiko-vancsa)]

Multi-attach functionality is now implemented in both Cinder and Nova, which should make this bug invalid. In case the symptom appears again the bug shall be re-opened.

Blueprint page with more details: https://blueprints.launchpad.net/nova/+spec/multi-attach-volume