Re: [Qemu-block] using "qemu-img convert -O qcow2" to convert qcow v1 to v2 creates a qcow v3 file?

[Peter Maydell]

On 13 November 2017 at 17:14, Peter Maydell <address@hidden> wrote:
> I have a qcow v1 file which I created by mistake (forgetting that
> you need to tell qemu-img create 'qcow2' and not just 'qcow'),
> which I want to convert to a v2 file so I can put snapshots into
> it. But when I try to do this with qemu-img convert it creates a
> v3 file instead:
>
> $ file hda-old.qcow
> hda-old.qcow: QEMU QCOW Image (v1), 5368709120 bytes
> $ build/x86/qemu-img convert -O qcow2 hda-old.qcow hda.qcow2
> $ file hda.qcow2
> hda.qcow2: QEMU QCOW Image (v3), 5368709120 bytes
>
> and if you then try to use that in QEMU it complains:
>
> qemu-system-aarch64: -drive if=none,file=hda.qcow2,format=qcow,id=hd:
> Unsupported qcow version 3

ah, this means it wants "format=qcow2".

This is pretty confusing, especially the error message, the
output of "file", and the fact that "format=qcow" can't just
DTRT if it gets a qcow version 3 (2?), since it can clearly
identify what it's got.

thanks
-- PMM