Re: zero out blocks of freed user data for operation a virtual machine environment

Thomas Glanzmann
2009-05-25T10:50:36Z

Hello Ron,

* Ron Yorston <rmy@tigress.co.uk> [090525 09:49]:
> I've written a tool to zero freed blocks in ext2/ext3 filesystems, as well
> as a (half-baked) kernel patch. Details here:

> http://intgat.tigress.co.uk/rmy/uml/sparsify.html

nice work! While talking about sparse files: Do you know if there is an
option for qcow2 to reclaim zeroed out blocks (like a sparse in
userland)? I hope that this functionality hits upstream. It could also
used to provide a secure file deletion.

Thomas