Retype a volume

If you created a volume with the wrong storage type you are able to retype it. Perhaps you’ve noticed that a disk was to heavily utilised causing IO-wait on your instances because it was placed on HDD storage and would like to change it to SSD. The other scenario might be a volume has grown and is to expensive to host on SSD.


NVMe volumes are different! They are locally placed on the hypervisors and cannot be retyped. If you need to move to NVMe, you would need to setup an instance based on a NVMe flavor, attach your current volume, move the data and then de-comission the old volume.

The following two requirements must be met to re-type volumes that are attached to instances:

  • The instance must be running.

  • There must not be snapshots on the volume.

Any deviations will cause a silent fail. A volume that is not attached also cant have any snapshots but will otherwise be possible to just retype at convenience. A retype may take several hours, the instance is available during this time but may have reduced IO during the swap-over. We recommend doing this procedure during the night time (when IO is likely less).


As retyping involves copying all the data of the instance, we strongly recommend first backing it up before proceeding.

Cloud management portal

Its currently not possible to retype volumes using the cloud management portal.

OpenStack Horizon

To retype a volume using OpenStack Horizon, follow these steps:

  • Under “project”, click “compute” and then “instances” in the sidebar menu.

  • Press the name of the instance from which you want to remove a volume.

  • At the bottom, under the “volumes attached” section, press the volume you want to retype.

  • Select “Change volume type” in the dropdown in the top right corner.

  • Select the new type.

  • In migration policy dropdown, select “On demand”.

  • Press “change volume type”.

  • A progress bar will show during the retype procedure (which may take several hours).

OpenStack Terminal Client

To retype a volume using the OpenStack terminal client, follow these steps:

  • Run this command: openstack server list, save the name of the instance to which the volume you want to extend is connected.

  • Run this command: openstack server volume list [NAME_OF_INSTANCE], replacing the name with that from previous step.

  • Run this command: openstack volume type list, save the name of the new volume type you want to use (ssd or hdd).

  • Run this command: openstack volume set --type [TYPE_NAME] [VOLUME_ID] --retype-policy on-demand, replacing the items in angle brackets with the type name (hdd/ssd) and the ID of the volume from previous steps.

  • Run this command to verify: openstack volume show [VOLUME_ID] -c status, when the status changes from “retyping”, the retype is done.