Suggestion: bmap files and bmaptool

[Richard W.M. Jones]

On Thu, Aug 15, 2013 at 12:34:26PM -0500, Eric Sandeen wrote:
> But then there's the issue of transporting these sparse files
> around.  We have had the same problem in the past with large e2image
> metadata image files, which may be terabytes in length, with only
> gigabytes or megabytes of real data.  e2image _itself_ creates a
> sparse file, but bzipping it or rsyncing it still processes
> terabytes of zeros, and loses all notion of sparseness.

xz preserves sparseness.  We use it for preserving and compressing
virt-sparsify'd images.

> Another approach which might (?) be more robust, is to somehow
> encode that sparseness in a single file format that can be
> transported/compressed/copied w/o losing the sparseness information,
> and another tool to operate efficiently on that format at the
> destination, either by unpacking it to a normal sparse file or
> piping it to some other process.

qcow2 :-)

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)