Using Ubuntu installer CD to securely erase a hard drive
In most instances, when you have an old hard disk you want to erase, I would say go and download the latest version of DBAN (http://www.dban.org/) and wipe away! However, I have found that on occasion, depending on the hardware being used, you may not be able to boot off the DBAN disk. I had one such instance where I was trying to erase the hard drive in a Lenovo ThinkPad T61. DBAN kept crashing during boot, presumably as it tried to come to terms with the fact the machine has an inbuilt SD card reader. In the end I gave up on DBAN and did the following:
1. Downloaded an ISO of the latest Ubuntu installer releast, in this case 11.04, and burnt it to CD.
2. Booted off the CD.
3. When asked if I wanted to Try Ubuntu or Install Ubuntu, I chose to Try it!
4. Once into the Ubuntu environment, I fired up the Terminal program.
5. Became the root user
6. Used shred to erase the drive:
/usr/bin/shred -f -v -z -n 7 /dev/sda
This will run 7 passes of random data over the drive and then zero the whole drive, while showing you the status. I let it run overnight and in the morning I had a nice clean drive :)