Open Stack

On Tue, Nov 12, 2013 at 10:24 AM, Trivedi, Narendra
<Narendra.Trivedi at savvis.com> wrote:
> Hi All,
>
>
>
> Could someone please explain the Cinder multi-backends feature (as of
> Havana)? Specifically, I had the following questions:
>
>
>
> 1)      Can I attach multiple physical storage backends (let’s say one all
> SSD, another all SATA for instance) to a single host?
>
> 2)      How does migration between different multiple backends work? Let’s
> say the an SSD volume is attached to a VM I want to migrate all the data in
> the SSD volume to a SATA volume without bringing down the interface. Do I
> have to manually mount/un-mount the persistent volume to the instance- how
> do paths are maintained? For instance, let’s say the persistent volume was
> /dev/vdx mounted to /mnt/vol0 , how does it re-appear ?
>
>
>
> Thanks a lot in advance!
>
> Narendra
>
>
>
>
>
>
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Hi Narendra,

Yes, the whole point is in fact that you can have multiple physical
backends controlled by a single host.  Of course it still needs to be
a cinder supported backend/driver.  To configure this you can check
out the following link [1].

With respect to the migration, you should be able to run "migrate
<volume-id> <host>", where host is the hostname of the backend you
want to migrate too.

John

[1] https://wiki.openstack.org/wiki/Cinder-multi-backend