[Gllug] Wiping free space.

[James Courtier-Dutton]

2009/12/28 general_email at technicalbloke.com <general_email at technicalbloke.com>:
> I was wondering how one would go about overwriting empty space on a
> standard ext3 partition. The quickest naive solution would seem to be to
> pipe the output of /dev/random to a file until all the disk space is
> used then delete it but...
>
> a) I've heard bad things may happen if the system disk get completely
> full on unix systems, and...
>
> b) AFAIK, files are block aligned so files which don't divide perfectly
> into the block size may have space at the very end of that the OS
> doesn't regard as free.
>
> Are the above conerns legitimate or just here-say? If the former are
> there any apps I would find in the big 3 repos that overwrite unused
> space while mitigating the above?
>
>
> Roger.
> --

Roger,

I don't know exactly why you would want to do this.
If it is because the data is private and you want to properly delete
it then another approach would be better.
I would recommend encrypting with LUKS or some other tool the entire
partition and store your private data there.
Then, even if the HD crashes, you can still be sure that your private
data is safe.

There are other reasons why one might wish to write zeros, for
example, in order to compress an entire HD backup.

Kind Regards

James
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