Re: [Qemu-devel] Re: qcow2 corruption observed, fixed by reverting old change

Jamie Lokier
2009-02-15T02:27:26Z

Dor Laor wrote:
> Both qcow2 and vmdk have the ability to keep 'external' snapshots.

I didn't see any mention of this in QEMU's documentation. One of the
most annoying features of qcow2 is "savevm" storing all VM snapshots
in the same qcow2 file. Is this not true?

> In addition to what you wrote, qcow2 is missing journal for its meta
> data and
> also performs poorly because of complex meta data and sync calls.
>
> We might use vmdk format or VHD as a base for the future high
> performing, safe
> image format for qemu

You'll want to validate VHD carefully. I tested it just yesterday
(with kvm-83), and "qemu-img convert" does not correctly unpack my VHD
image (from Microsoft Virtual PC) to raw, compared with the unpacked
version from MSVPC's own conversion tool. There's some patches which
greatly improve the VHD support; I'm not sure if they're in kvm-83.

-- Jamie