nova can't detach volume after force detach in cinder

[wanghao]

There is use case: we have two nova components（call them nova A and nova B） and one cinder component. Attach a volume to an instance in nova A and then services of nova A become abnormal. Because the volume also want to be used in nova B, so using cinder api "force detach volume" to free this volume. But when nova A is normal, nova can't detach this volume from instance by using nova api "detach volume" , as nova check the volume state must be "attached".

I think should we add "force detach" function to nova just like "attach" and "detach", because if using force detach volume in cinder, there is still some attach information in nova which can't be cleaned by using nova api "detach".

[Nikola Đipanov (ndipanov)]

I'd say this is a reasonable thing to propose, although since forcing in cinder is an admin only command - I am thinking this should be as well. Also I fear there could be edge cases where we really should not allow even the force detach (see https://bugs.launchpad.net/nova/+bug/1240922 where we might want to disable attach for suspended instances).

Having all this in mind makes me think this needs to be a BP rather than a bug - so I will move this to Won't fix, and the reporter might propose this as a Bluepring for Juno.

[wanghao (wanghao749)]

Thanks for suggestion, there is the BP: https://blueprints.launchpad.net/nova/+spec/add-force-detach-to-nova