Open Stack

On 29/08, Albert Braden wrote:
> We’re replacing controllers, and it takes a few hours to build the new controller. We’re following this procedure to remove the old controller: https://docs.openstack.org/kolla-ansible/train/user/adding-and-removing-hosts.html
>
>  After that the cluster seems to run fine on 2 controllers, but approximately 1/3 of our volumes can’t be attached to a VM. When we look at those volumes, we see this:
>
> | os-vol-host-attr:host          | qde4-ctrl1.cloud.ourdomain.com at rbd-1#rbd-1                            |
>
> Ctrl1 is the controller that is being replaced. Is it possible to change the os-vol-host-attr on a volume? How can we work around this issue while we are replacing controllers? Do we need to disable the API for the duration of the replacement process, or is there a better way?
>

Hi,

Assuming you are running cinder volume in Active-Passive mode (which I
believe was the only way back in Train) then you should be hardcoding
the host name in the cinder.conf file to avoid losing access to your
volumes when the volume service starts in another host.

This is done with the "backend_host" configuration option within the
specific driver section in cinder.conf.

As for how to change the value of all the volumes to the same host
value, you can use the "cinder-manage" command:

  cinder-manage volume update_host \
    --currenthost <current host> \
    --newhost <new host>

Cheers,
Gorka.