How to Completely Erase a Hard Disk Drive

If you’re ready to invest in a new computer, and your thinking about donating your old computer to a charity, local group or school, it’s important to make sure your computer’s hard drive is completely free of data.

In the “no good deed ever goes unpunished” department, you need to ensure that you don’t donate more than you planned. The last thing you want is to pass on a PC when sensitive business information, or even personal information such as stored passwords, personal documents and credit card numbers that could be retrieved. When you donate a computer, you don’t know where it may end up or if it will go through the hands of a malicious person with the capability to restore previously recorded and deleted data.

There are many ways to keep your data from being retrieved. Obviously, you can choose to physically smash the drive, but there are alternatives that enable you to keep the system intact so you can donate a complete system.

Erasing and Formatting — Just Not Secure Enough

Simply erasing all the data on your hard drive and formatting it is not enough security. You can spend hours going through your hard drive and deleting all the files and documents you want but, in Windows, using the delete key on your keyboard basically only removes the shortcuts to the files making them invisible. Deleted files still reside on the hard drive and a quick Google search will show many system-recovery software programs that will allow anyone to reinstate that data.

Formatting the hard drive is only slightly more secure than erasing the files. While formatting erases only the address tables, not the data on the disk, it makes it much more difficult to recover the files. However a computer specialist would be able to recover most or all the data that was on the disk before the reformat.

If you accidentally reformat a hard disk, being able to recover most or all the data that was on the disk is a good thing. However, if you’re preparing to retire or donate a system, this obviously makes you more vulnerable to data theft.

For some businesses and individuals, a disk format may be something you consider secure enough, depending, of course, on the type of data and information you saved to your computer. As long as people understand that formatting is not a 100 percent secure way to completely remove all data from your computer, then they can make an educated choice between formatting and even more secure methods. If you have decided a disk format is a good choice, at the very least to do a full format rather than a quick format.

Disk Wiping Options (a.k.a. Data Dump)

Even more secure than reformatting is a process called disk wiping. The term disk wiping is not only used in reference to hard drives but with any storage device such as CDs, RAIDs or thumb drives. Disk wiping is a secure method of ensuring that data, including company and individually licensed software on your computer and storage devices is permanently deleted before recycling or donating the equipment.

The right software applications can restore previously stored data, so the disk wiping process will actually overwrite your entire hard drive with data, several times. Once you format the newly wiped drive, you’ll find it all but impossible to retrieve the data that was on the drive before the disk wipe.

While disk-wiping algorithms differ from product to product, they all generally write the entire disk with a number (zero or one), after which you’ll need to reformat the drive. The more times the disk is overwritten and formatted the more secure the disk wipe is, but the trade-off is the extra time to perform additional rewrites.

The government standard (DoD 5220.22-M), considered a medium-security level, specifies three iterations to completely overwrite a hard drive six times. Each instance makes two write-passes over the entire drive; the first pass inscribes ones (1) over the drive surface and the second inscribes zeros (0) onto the surface. After the third iteration, a government-designated code of 246 is written across the drive, and then a final pass verifies the process.

You can buy or download a variety of products to perform more secure disk wipes. If time to perform the disk wipe is a consideration, there are also tech security companies who offer disk wipe services.

Adapted from webopedia.com.