Nova on RBD Device

Nova on RBD Device

[Mandell Degerness]

Can anyone point me in the right direction for setting up Nova so that
it allocates disk space on RBD device(s) rather than on local disk as
defined in the --instances_path flag?

I've already got nova-volume working with RBD.

I suspect that I need to modify _cache_image and _create_image in
nova/virt/libvirt/connection.py.

Regards,
Mandell Degerness

Re: Nova on RBD Device

[Florian Haas]

On Tue, Feb 7, 2012 at 8:01 PM, Mandell Degerness
<mandell@pistoncloud.com> wrote:
> Can anyone point me in the right direction for setting up Nova so that
> it allocates disk space on RBD device(s) rather than on local disk as
> defined in the --instances_path flag?
>
> I've already got nova-volume working with RBD.
>
> I suspect that I need to modify _cache_image and _create_image in
> nova/virt/libvirt/connection.py.

Hmmm. Wouldn't that most likely be a question for the openstack list?
http://wiki.openstack.org/MailingLists for details on how to
subscribe, if you haven't already.

Cheers,
Florian

-- 
Need help with High Availability?
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Re: Nova on RBD Device

[Josh Durgin]

On 02/07/2012 11:01 AM, Mandell Degerness wrote:
> Can anyone point me in the right direction for setting up Nova so that
> it allocates disk space on RBD device(s) rather than on local disk as
> defined in the --instances_path flag?

You probably want to use the boot-from-volume api extension. I think 
there's support in nova-client for this now.

> I've already got nova-volume working with RBD.
>
> I suspect that I need to modify _cache_image and _create_image in
> nova/virt/libvirt/connection.py.

Nova itself doesn't know how to do I/O to volumes - it just knows how to 
configure a hypervisor to use one. You'll need to attach the volume to 
an existing vm to write an image to it, or use a hack like:

rbd rm pool/image && qemu-img convert -f raw -O rbd /path/to/img 
rbd:pool/image

In the future, once rbd layering is implemented, we'd like to be able to 
store images in rbd via glance, and clone them into bootable nova volumes.

> Regards,
> Mandell Degerness