Firstly one does not run this as root. run this as a normal user. The system reserves some space for the root user, and this way you will not run out of disk space for critical system. (At least I know this to be true for reiser, ext3 and ext2 filesystems on Linux.

Secondly, anyone paranoid enough to want to do it should never use /dev/zero (Not even when doing it multiple times) since you can still get the data using forensic techniques. Even if you do this multiple times... some drives with advances caching may not even do the successive writes on a very low level (even with only a small sized disk-cache).

Lastly, yes, /dev/random is more cpu intensive... as for a lot more? No it does not:

I did:
(cat /dev/zero > zero &) ; (cat /dev/random > random &) ; sleep 20 ; killall cat ; ls -l zero random

And it showed:

joseki:~ marius$ ls -la random zero
-rw-r--r-- 1 marius staff 222302208 Apr 24 12:27 random
-rw-r--r-- 1 marius staff 666898432 Apr 24 12:27 zero

So, yes, I would suggest using random... a good system-wide anti-entropic engine should be pretty efficient.


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I would think that this could be equally useful using /dev/random or /dev/zero. ramdom would help obscure old data from disk searches. zero would allow for the raw partition to be more easily compressed.

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