Re: [Qemu-devel] storing machine data in qcow images?

[Kevin Wolf]

Am 28.05.2018 um 20:30 hat Richard W.M. Jones geschrieben:
> On Mon, May 28, 2018 at 08:10:32PM +0200, Max Reitz wrote:
> > As someone who is just naive and doesn't see the big picture, I don't
> > see what's wrong with using a tar file that contains the image and
> > additional data.
> 
> FWIW an OVA file is exactly this: an uncompressed tar file containing
> disk image(s) and metadata.

If we combine VM configuration and the disk image this way, I would
still want to directly use that combined thing without having to extract
its components first.

Just accessing the image file within a tar archive is possible and we
could write a block driver for that (I actually think we should do
this), but it restricts you because certain operations like resizing
aren't really possible in tar. Unfortunately, resizing is a really
common operation for non-raw image formats.

And if I think of a file format that can contain several different
things that can be individually resized etc., I end up with qcow2 in the
simple case or a full file system in the more complex case.

Kevin