Multi-Attached volume support

Registered by Akihiro Motoki

Nova and Cinder Queens release finally support multi-attached volume.

It is originally filed as bug 1751564 but it turns out we need more effort with multiple commits, so this blueprint is filed.

Blueprint information

Akihiro Motoki
Vishal Manchanda
Vishal Manchanda
Series goal:
Accepted for 16.0.0-train
Milestone target:
milestone icon train-3
Started by
Akihiro Motoki
Completed by
Vishal Manchanda


Status as of Aug 8, 2019 -- amotoki

The main patch has been merged.
Only remaining item looks like the following minor improvements:
- The table of "Manage Attachments" dialog from the volume table is wrong when a multi-attach volume is being attached to multiple server instances. I see a single server name twice when a volume is attached to two servers. (bug 1700034 looks like the one.)


Initial patch with basic support:

This blueprint needs to be updated to follow the blueprint template

Gerrit topic:,topic:bug/1751564,n,z

Addressed by:
    Use microversion 2.60 when attaching a multiattach volume

Notes from Akihiro on what should also be addressed in this blueprint:

* Depending on qemu and libvirt versions, even though the nova API and volume multiattach attribute say the multi-attach is supported, there is a case where the multiattach cannot be used. We need to raise a clearer error message for that case. At now, "Unable to attach volume." is shown.
* multi-attachable volumes attached to other instances are not listed in "Attach Volume" form from the instance table.
* "Manage attachments" action of the volume table needs to take into account multi-attachable volumes.
* allow_multiattach attribute needs to be specified during volume creation.

-- mriedem 20180424

For anyone interested in working on this, here is a short demo on setting up a devstack environment and working with multiattach volumes:

Addressed by:
    Allow to select multiattach volume that has been attached

Gerrit topic:

Gerrit topic:

Addressed by:
    Wrong list of attached vms are shown in manage volume attachments


Work Items

Work items:
Attach multiattach capable volumes to server using compute API version 2.60: DONE
Improve error handling for specific multiattach failures: TODO
Show all instances attached to multiattach volume in "Attach Volume" form in instance table: TODO
"Manage attachments" action of the volume table needs to take into account multiattach volumes: TODO
Add the ability to create multiattach-capable volumes during volume creation (this might not be necessary since you can already do this in Horizon today): TODO

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