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

[Richard Pieri]

On Feb 17, 2010, at 2:24 PM, Tom Metro wrote:
> 
> If you have adequate space on the target system, you could always use a 
> hack with tar to "de-sparse" the file, and then incrementally back it up 
> using some other tool, like rsync.
> 
> tar -cf - /path/to/sparse | gzip --rsyncable > sparse.tgz
> 
> (You'll need a gzip port with the --rsyncable patch too.)

For optimal performance with this trick you should zero out freed sectors on the sparse image and then compact the image.  Very efficient usage of the storage, but it's slow and tedious.

--Rich P.