[openstack-dev] what code in cinder volume driver supports volume migration between two backends of same type but having different volume types?

Avishay Traeger avishay at stratoscale.com
Wed Jan 21 19:51:23 UTC 2015

On Mon, Jan 19, 2015 at 8:01 PM, Nikesh Kumar Mahalka <
nikeshmahalka at vedams.com> wrote:

> do cinder retype (v2) works for lvm?
> How to use cinder retype?

As far as I remember, LVM doesn't really leverage volume types.  What types
did you define, and what command are you running?

> I tried for volume migration from one volume-type LVM backend to
> another volume-type LVM backend.But its failed.
> How can i acheive this?

It should work.  Please provide the commands you ran, the result, and all
relevant logs.

> Similarly i am writing a cinder volume driver for my array and want to
> migrate volume from one volume type to another volume type for my
> array backends.
> so want to know how can i achieve this in cinder driver?

There are several driver APIs that you can implement.  First, you are most
likely inheriting generic migration/retype from the base driver class.
This works by creating a new volume, and moving data from the original to
the new either using the hypervisor (for an attached volume) or by
attaching  both volumes to a server running cinder-volume and running dd.
Your driver may be able to do more optimized migrations/retypes by
implementing the respective APIs.  The IBM storwize/svc driver implements
both, as do several others - I suggest you look at them for examples.


*Avishay Traeger*
*Storage R&D*

Mobile: +972 54 447 1475
E-mail: avishay at stratoscale.com

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