Backing up system

[Roberto Ragusa]

Bill Crawford wrote:
> On Friday 27 March 2009 09:01:30 Michael D. Setzer II wrote:
> 
>> It does work best if you clear unused space before doing an image to reduce
>> space since the null filled sectors compress to almost nothing.
> 
> How do you do that?

head -c 100000000 /dev/zero >100mega

will create a file with 100 million zeros.
You create as many files as your free space requires, until
the disk is almost full.

Then you delete them all. The disk blocks will keep their
values (zeros) and most of your free space will now be clean.

Slow if you have a lot of free space, but the trick works with
any kind of filesystem (if it is not compressing or encrypting,
that is).

Best regards.
-- 
   Roberto Ragusa    mail at robertoragusa.it