[Openstack] Cinder: Migrate Volume to VMDK backend

Oisin O'Malley oisin.omalley at iocane.com.au
Mon Aug 21 05:44:00 UTC 2017

Hi Vanay,

Thanks for the suggestion. I've used "qemu-img convert" before to manually migrate the other direction VMDK -> RAW/COW2. It's a great tool.

Specifically, I'm curious if the volume migration process can be managed by Cinder.

For instance, we currently have 2 Cinder backends in production, NetApp NFS and HPE 3Par FC. A Cinder type is associated with each Cinder backends, you can then migrate a cinder volume between these via the command "cinder retype <volume-id> <volume-type> --migration-policy on-demand". In this case, the Cinder-volume service converts the volume from a .RAW file on a NFS filesystem, to a Fibre Chanel LUN on the 3par or visa-versa.

If I had a VMDK backend in Cinder setup as another Cinder volume type, can you use Cinder to change the volumes backend and migrate the volume? For instance, can I do a "cinder retype/migrate <volume-id>" to convert the volume from a .RAW on a NetApp backend to a .vmdk on VMDK backend?

The Cinder documentation is quite unclear about this.

> You should be able to do this. I've done this many times using the qemu-img tool and using the covert option. It should allow you to convert the volumes from raw to vmdk's.
>Additionally, if you are not doing anything too fancy and not at scale you can also possibly look at the VMware Converter product. (I don't work for VMWare).
>Hope this helps.
>- Vinay


Oisin O'Malley
Systems Engineer
Iocane Pty Ltd
763 South Road
Black Forest SA 5035

Office:+61 (8) 8413 1010
Fax:+61 (8) 8231 2050
Email:oisin.omalley at iocane.com.au

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