On 11/13/2017 11:29 AM, Peter Maydell wrote: > On 13 November 2017 at 17:14, Peter Maydell <peter.mayd...@linaro.org> 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".
Oh, I should have read this followup before writing my other reply. > > 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. Indeed, making the qcow driver smart enough to reopen with the qcow2 driver (for both v2 and v3 images) might be an interesting ease-of-use hack. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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