Backing up sparse files ... VM's and TrueCrypt ... etc

[blu-Z8efaSeK1ezqlBn2x/YWAg at public.gmane.org (Edward Ned Harvey)]

Does nobody backup sparse files?  I can't believe there's no good way to do
it.  Of particular interest, I would like to backup:

.         TrueCrypt sparse files in Windows (Truecrypt calls this
"Dynamic.")

.         Virtualbox, or VMWare Workstation sparse ("expanding") virtual
disks in windows

.         VMWare Fusion or Parallels sparse virtual disks in Mac

 

I would like to back these up frequently, and efficiently.  If I have a 50G
container file that occupies 200M on disk, the backup should be close to
200M, and when I modify 1M in the middle of the file and then save, I don't
want the incremental backup trying to send the whole 50G again.

 

On the mac, the Sparsebundle concept solves this problem.  It's just like a
truecrypt image, but it's broken up into a whole bunch of little 8M chunks.
So when I modify 1M in the middle of the volume and save, my next backup
will send one updated 8M chunk for backup.  A little bit of waste, but well
within reason.

 

I currently have Virtual Machines and TrueCrypt images excluded from the
regular Time Machine and Acronis True Image backups of peoples' laptops.
But I'm not comfortable simply neglecting the VM's and TrueCrypt volumes, as
if they're not important.

 

I haven't found anything satisfactory yet.  The closest I found so far was
Crashplan.  It does "byte pattern differential" and "continuous real-time
backup," which means it can detect blocks changing in the middle of a file,
and only send the changed blocks of a sparse file during incrementals,
instead of sending the whole 50G again.  Unfortunately, crashplan can't
restore a sparse file.  D'oh!!!   :-(   Actually, that's a fib.  It can
restore sparse files, but they won't be sparse anymore.  So . IMHO . that's
not useful.

 

I've also tried rsync.  People all over the place say it should do well, but
in practice, I found that doing a single incremental takes 2x longer than
doing the whole image.  So again, IMHO, not useful.  Unless I am simply
using it wrong.  But I put plenty of effort into making sure I was using it
right, so I'm really pretty sure I didn't get that wrong.

 

Anybody doing anything they're happy with, to backup sparse files on a
regular basis, quickly, efficiently, frequently?

 

Thanks.