If you want to remove all the info from a partition, you don't need to unmount it. You can overwrite the whole of it (that's even more secure because the information about which file was where will be also removed). All you need is the partition name (like /dev/hda1). Find it out (you have probably already done it).
Then look if you have openssl installed. It has a nice option, rand, that produces random values. You can overwrite the whole partition this way. To learn more about it, run 'man rand'.
The command will be rather simple (but make sure you're using right partition name, because you'll remove everything!). It's something like
openssl rand -out /dev/hda1 100000
The last parameter is size (in bytes). You can test it with smaller one first to see if it works correctly (because it'll take some time when run on N GB).
Edit: if you want it really impossible to recover, repeat ten times or so.
Last edited by Mara; 12-09-2005 at 04:12 PM.