Re: [Libguestfs] How to use libguestfs access LVM as non-root user?
On 06/01/2013 02:27 PM, Richard W.M. Jones wrote:
On Sat, Jun 01, 2013 at 01:28:20PM +0800, Qiu Yu wrote:
> For others who might interests, if you use qcow2 image with OpenStack and
> choose LVM as image backend, nova libvirt driver will convert it raw when
> creating a new instance.
IIUC, that's the reason, why it converts to raw --
https://github.com/openstack/nova/commit/ff9d353b
-------------------------
"This uses 'qemu-img' to convert images that are not 'raw' to be
'raw'.
By doing so, it
a.) refuses to run uploaded images that have a backing image reference
(LP: #853330, CVE-2011-3147)
b.) ensures that when FLAGS.use_cow_images is False, and the libvirt
xml written specifies 'driver_type="raw"' that the disk referenced
is also raw format. (LP: #837102)
c.) removes compression that might be present to avoid cpu bottlenecks
(LP: #837100)
It does have the negative side affect of using more space in the case where
the user uploaded a qcow2 (or other advanced image format) that could have
been used directly by the hypervisor. That could, later, be remedied by
another 'qemu-img convert' being done to the "preferred" format of the
hypervisor."
-------------------------
It also does it during nova-image-create. A small write-up on how/why --
http://kashyapc.wordpress.com/2013/03/11/openstack-nova-image-create-unde...
However, data injection using libguestfs will
> still assuming the it is qcow2 format, hence hit the above issue.
Not sure
> it is a bug or not, probably one should specify "use_cow_images = False"
to
> avoid the problem in this case.
Yes, this sounds like a Nova bug.
Rich.
--
/kashyap