I can partially answer myself.
This is a feature, which prevent inconsistencies from nova/cinder.

https://review.opendev.org/c/openstack/nova/+/768352
https://bugs.launchpad.net/nova/+bug/1909120

Now, I am wondering if multiattach could be a partial solution?

Cheers,
Arnaud


On 20.03.25 - 13:49, Arnaud Morin wrote:
> Hey team,
>
> Is there any way to force detach a volume when the nova compute service
> is down? Like when the hypervisor is off, we want to detach the volume
> and attach it to another instance.
>
> Maybe I'm missing the way to do it, but detach action on nova side seems
> a synchronous task that I can't force without admin creds.
>
> Thanks for any help,
>
> Regards,
> Arnaud