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

[tmetro-blu-5a1Jt6qxUNc at public.gmane.org (Tom Metro)]

Richard Pieri wrote:
>> tar -cf - /path/to/sparse | gzip --rsyncable > sparse.tgz
> 
> 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.

That would be true if tar read the sparse file as an ordinary file, but 
I'm assuming it knows how to properly skip over the holes. I see there 
is an option to handle sparse files:

        -S, --sparse
               handle sparse files efficiently

I would expect with that option, you'll never see the junk that happens 
to be occupying the unused sectors.

  -Tom

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Tom Metro
Venture Logic, Newton, MA, USA
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