[Thincrust-devel] packaging of sparse raw disk images

[David Lutterkort]

On Fri, 2008-11-14 at 13:47 -0500, Perry Myers wrote:
> In the latest appliance-tools you can use .tar.bz2 among other formats for 
> packaging up your appliances.
> 
> I've tried building appliances with sparse raw disks and a disk that 
> should have been empty ends up being non sparse (and 20GB of zeros) after 
> extracting from the tar.bz2.
> 
> Doing a stupid sanity check, I did the following:
> qemu-img create -f raw foo.img 100M
> tar -cvf foo.tar foo.img
> tar -xvf foo.tar
> 
> And the image is non-sparse.

IIRC, if you pass --sparse to tar it behaves a little better; but it's
not ideal, and I think --sparse is a GNU extension.

David