How to erase data completely
We’ve discussed the ways in which your drive stores files and how they don’t really get removed when you delete them or format your drive. What if there are files on there that you really want to stay deleted, and be excluded from any recovery efforts? We can use a little of our knowledge of file storage to work out how to obliterate old data — the best way to make sure files don’t rise from the dead is to ensure that ‘free’ space on your drive is completely overwritten. You could painstakingly write files to your drive until it’s full, but that’s madness. Better to use a secure deletion tool.
You have a few choices here, but we tend to favor Eraser ( eraser.heidi.ie), which goes overboard in its efforts, overwriting your files several times with specific random data patterns in order to remove them — and on magnetic drives, the microscopic traces they leave behind — completely. We recommend you keep it hanging around: you can securely delete files just by dropping them on the app, or even have it grind through any unused space on your partitions, applying its algorithms to that space to scrub it clean of any ghostly data.
If you really want to get rid of all the data on a drive — if you’re passing your hardware on or recycling it, say — System Rescue CD includes the tool Wipe ( wipe.sourceforge.net), which does an intense, thorough, repeated overwriting of every byte of data on a drive. Or if the hardware doesn’t matter, and you’re absolutely desperate to get rid of it, do as one of APC’s alumni once did: Take a hammer to your drive and throw it in a lake. But think of the fish before you do it.
Eraser can make up to 35 passes over your data for absolute removal.