[libvirt-users] Create RBD Format 2 disk images with qemu-image

[Josh Durgin]

On 10/17/2013 05:28 AM, Jon wrote:
> Hello,
>
> I would like to use RBD Format 2 images so I can take advantage of layering.
>
> However, when I use "qemu-img create -f rbd rbd:data/foo 10G", I get
> format 1 RBD images. (Actually, when I use the "-f rbd" flag, qemu-img
> core dumps, but it looks like that feature may have been deprecated [1])
>
> Is there any way to have qemu-img create RBD Format 2 images or am I
> better off using `rbd` to create the image then booting from the disk
> and performing the install, etc.?

If you're using recent cuttlefish or dumpling releases of ceph, you can
add settings to ceph.conf to make qemu-img and anything else using
librbd create format 2 images. In the [client] or [global] section of
/etc/ceph/ceph.conf, add:

rbd default format = 2

Josh

> Thanks for the assist.
>
> Best Regards,
> Jon A
>
>
> [1]
> http://lists.ceph.com/pipermail/ceph-users-ceph.com/2013-June/002131.html
>
>
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