Originally Posted by PeterJD
So can I just use the dd command as described by Valery Reznic? And how long will it take? Otherwise it just seems too complicated. I'm not really paranoid.
I recently wiped my external harddrive with dd method. You can use the approach described in earlier posts. Two things I would recommend additionally:
1. tell dd to use a block-size of 1MB. This will speed up the process.
Using pixelany's suggestion:
# enter "dd if=/dev/urandom of=junk bs=1M"
# wait until it is done
# enter "rm junk"
# (optional) enter "dd if=/dev/zero of=junk bs=1M"
Although I did three passes first filling with zeros, then random and finally with zeros again.
2. To avoid locking up your system you could run the commands from a liveCD. You would have to mount your linux partition and create the output file on that partion:
mount /dev/sdxx /mnt
dd if=/dev/zero of=/mnt/junk bs=1M
where /dev/sdxx is your linux partition, e.g. /dev/sda2 or /dev/sdb4 ...
As for the time it will take, writing zeros happened at a speed of appr. 30MB/s, writing random was 4MB/s. So doing the math this results in 5 minutes/GB if you first fill random and then zeros.