[Openstack] Migrate volume from Essex to Folsom

pablo fernandez fernandezpablo85 at gmail.com
Thu Jul 4 16:16:45 UTC 2013

Leandro, Brano,

I'm effectively migrating only the openstack installation, the DFM remains
the same. However, if I read Brano's email correctly, besides migrating the
information on openstack DB I also have to change metadata that DFM, is
that right?

Here's an example of a volume I have on Essex right now:


And here's what DFM returns for that volume's LUN:


Is moving the data just from Essex db to Folsom safe in this case?

On Thu, Jul 4, 2013 at 12:08 PM, Leandro Reox <leandro.reox at gmail.com>wrote:

> Pablo,
> On folsom the block_device_mappings table its on novadb too, i totally
> miss the Brano's recommendation of uuid conversion and metadata, asumming
> that you hit the same dfm.
> We had to do that a couple of times, but generally as all our vms are
> stateless, we create them on the "new" cloud, and replicate the content,
> via sharding replicas or other mechanism, without intervention
> Saludos
> On Thu, Jul 4, 2013 at 11:27 AM, Brano Zarnovican <zarnovican at gmail.com>wrote:
>> On Wed, Jul 3, 2013 at 11:24 PM, pablo fernandez
>> <fernandezpablo85 at gmail.com> wrote:
>> > Hi list!
>> >
>> > Any advice on this? Has somebody already tried it (and hopefully
>> succeeded).
>> We did this migration "in-place". On day D, we dumped Essex
>> Openstack/DFM DB and restored in Folsom. I have created a patch for
>> Folsom Netapp driver to recognize Essex volumes/snapshots.
>> I assume that both your clouds are hitting the same DFM. Otherwise,
>> you would have to migrate entries not only between Openstack DB, but
>> DFM DB, too. Would be painful..
>> Folsom Netapp driver has added some meta-data to Openstack datasets
>> (in DFM), so Folsom will not recognize DFM datasets created in Essex
>> (and hence all Essex LUNs would be invisible). I have added that
>> meta-data manually with the attached script.
>> Volume is identified by (host, provider_location). Host is the one
>> running nova-volume, provider_location is an object id in DFM db.. eg
>> ("mgmt-netapp.example.com", 7574).
>> So if you are using the same DFM, provider_location won't change, but
>> you host probably would.
>> Problem would be that you need to migrate id from decimal to UUIDs. In
>> my case, this was done in Openstack DB as part of that in-place
>> migration. The mapping is stored in new table "volume_id_mappings".
>> Same comments apply also to snapshots. However, because of this UUID
>> change, volumes names (LUNs on Netapp) are expected in different
>> format.
>> Essex:
>> /OpenStack_103a49bb861e485ea05aa78f9b0216bd/vol-000009a4/vol-000009a4
>> Folsom:
>> /OpenStack_103a49bb861e485ea05aa78f9b0216bd/vol-dcc14978-4ff1-422b-97e7-f7f668718b9e/vol-dcc14978-4ff1-422b-97e7-f7f668718b9e
>> That was the reason for driver patch, so I did not have to rename
>> existing LUNs on Netapp and DFM.
>> It's almost easier to create all volumes in Folsom and dd the content ;-)
>> Regards,
>> BranoZ
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