By Nerino Petro at 4 May, 2007, 2:21 pm
We have all been asked or wondered at one time or another, how to securely delete data from a hard drive to ensure that it's not recovered by someone else. Simply erasing the data or deleting it doesn't actually destroy the data, but simply removes the index for where the data is located; until the physical sectors on the hard drive have new data written to them this data still exists. Wikipedia has a good explanation of file shredding here. For those who want to take absolutely no chance of any confidential information being recovered, the only proper way to ensure this is through destruction of the physical drive itself. This can be accomplished either through the use of a large grinder such as the government uses or through severe percussive impact (think beating it with a sledgehammer and remember to wear safety glasses). Others prefer to these use a drill to drive through the hard drive or to pound nails through it. These methods will guarantee the drive cannot be accessed by an unauthorized party; however, it also results in the destruction and usability of the hard drive.
For those who wish to take a less forceful approach, you can use wide array of data destruction utilities such as the free DBAN a.k.a. Darik's Boot and Nuke , or the commercial StompSoft Drive Washer, Nova Development Dry Erase Pro and Acronis Drive Cleanser, to name a few, all of which provide different erasure methodologies including US Department of Defense standards for the erasure and deletion of information. For more information, check out Wikipedia’s explanation here.
PC World has created a relatively short and useful video available on YouTube on how to erase data from your hard drives.
If you’re not up to do it yourself data erasure, you can contract with a company such as EMC to do this for you and provide written certification that the data has been destroyed.