Open Stack

On 22/08, Sean McGinnis wrote:
> >
> > The solution is conceptually simple.  We add a new API microversion in
> > Cinder that adds and optional parameter called "generic_keep_source"
> > (defaults to False) to both migrate and retype operations.
> >
> > This means that if the driver optimized migration cannot do the
> > migration and the generic migration code is the one doing the migration,
> > then, instead of our final step being to swap the volume id's and
> > deleting the source volume, what we would do is to swap the volume id's
> > and move all the snapshots to reference the new volume.  Then we would
> > create a user message with the new ID of the volume.
> >
>
> How would you propose to "move all the snapshots to reference the new volume"?
> Most storage does not allow a snapshot to be moved from one volume to another.
> really the only way a migration of a snapshot can work across all storage types
> would be to incrementally copy the data from a source to a destination up to
> the point of the oldest snapshot, create a new snapshot on the new volume, then
> proceed through until all snapshots have been rebuilt on the new volume.
>

Hi Sean,

Sorry, I phrased that wrong. When I say move the snapshots to the new
volume I mean to the "New Volume DB entry", which is now pointing to the
old volume.

So we wouldn't really be moving the snapshots, we would just be leaving
the old volume with its snapshots under a new UUID, and the old UUID
that the user had attached to Nova will be referencing the new volume.

Again, sorry for the confusion.

Cheers,
Gorka.