Erasing Data from an Old PC

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The Background

As businesses upgrade PCs and laptops when old machines either run out of steam or fail, the question of what to do with an old computer arises.

If a machine isn’t too old, it may be re-usable, perhaps as a PC for home use or it might even be possible to sell on eBay. If the machine is too old to be of further use, it will need to be disposed of.

Whether it’s re-use or disposal, what about the data on the disk? The company’s financial records, the customer accounts, the detailed records of your business may all stored on the hard drive and any information needs to be removed before you and it part company.

If you're getting a PC support business to take away old kit, check with them on how any disks will be cleaned. You could ask them to do this before the kit is removed, or even ask them to leave the disks with you for distruction. See Physical Shredding at the end of this article and maybe take a look at the video...

How Windows Works

Think of the way Windows Explorer and the files it lists a bit like how your local library works.

In a library, the index catalogue shows you what books are available and where they’re kept. When you see a book you want, the index tells you which shelf you can find it on and over you go, pull out the book and open it up.

Throwing away the index wouldn’t remove the books from the shelves and it’s a similar situation with the Windows and disk drives.

Windows Explorer shows a catalogue of files on your hard drive. Deleting a file doesn’t remove the data it contains from the hard drive, it simply tells Windows that the space is available to re-use when needed. When you create a new file it may use some or all of the space that was used by the file you deleted. Or it may not!

Simply deleting files and folders in Windows Explorer doesn’t remove the data from the disk!

Scrubbing your Disk

To delete a file in a way that not only removes its entry in Windows Explorer, but also the data in the file (think: remove the card index entry from the library index and then shred the book) the free, open source software package Eraser is available from http://eraser.heidi.ie/ can be used.

However, when disposing of a PC, erasing everything securely from where you store your data – usually “My Documents” – may not be enough!

Windows can store copies of your files in different places to make it easier and quicker for you to get to your data. Internet Explorer can store a great deal of what you access on the Internet to speed up your browsing. Where it puts all this data isn’t in places that you’ll be able to find easily.

If you’re disposing of a PC or laptop, you need to make sure that the whole disk drive has been erased.

Shredding your Disk

As Windows uses the disk for its own internal processes, you can’t wipe the disk when Windows is running. Instead, some disk wiping software is loaded from a CD instead of Windows when the machine starts and this can be used to wipe the disk or disks in the machine.

One free utility that will do this is DBAN, which can be downloaded from http://sourceforge.net/projects/dban/ in a format that Windows should be able to write a CD from.

Booting from this CD then enables the whole disk to be wiped in a secure way, while enabling the disk to be reused.

Physical Shedding

Of course, another way to make the data on a hard drive unreadable might involve a large hammer!

This is straightfoward for a small business, but for those with larger disposal requirements, physical disk shedders are available - click here to take a look at one!