PC Hell: Deleting Hard Drive Data vs. Physically Destroying Hard Drive

What if your old hard drive ends up in the wrong hands? Your tax return, financial records, intimate photos, and more could be used against you.

During the 2007 NBA Playoffs, an interesting article appeared. It seems the San Antonio Spurs guard, Bruce Bowen, and his wife had filed a lawsuit against a local computer firm when their hard drive and data ended up on another person's computer. The recipient of the hard drive contacted Mr. Bowen and informed him of the breach of privacy. As a computer consultant myself, I see a huge breach of computer privacy with this case and I could see Mr. Bowen winning the lawsuit easily.

Now what can you do to avoid a similar situation as Mr. Bowen's? First you have to decide if you want to permanently erase the data or destroy the drive. If you decide to permanently erase the data, you have several options. However let's go over what you DON'T want to do.

What Not To Do

Don't just delete your data and empty the recycle bin
Don't just format the hard drive
Don't just format and reinstall Windows or another operating system

Why don't you want to do the above? It seems this would be enough to make sure your data isn't compromised.

Let's take a step back and understand how data is stored on a hard drive. When information is written to a drive, the location of the information is stored in a file that resembles a table of contents for a book, On computers running DOS and Windows operating systems, the File Allocation Table (FAT) or the Master File Table (MFT) holds this information. When a file is deleted, the FAT or MFT table is updated to tell the computer the space on the hard drive is available, however the actual data is not deleted until it is overwritten with new data. This is why you read about computer forensic teams, the FBI, and other law enforcement being able to recover data to solve crimes or incriminate individuals. Using software undelete tools, you can restore files that were accidentally or otherwise deleted. In more severe case, services such as Drive Savers are used to recover data that has been physically or electronically destroyed.

You can use the procedures below to erase or destroy your data so the average individual won't be able to recover anything from your computer hard drive.

Using Wipe Utilities

In order to prevent data from being recovered, you should use data wiping software to completely erase the information. Disk wiping overwrites each individual sector on a hard drive multiple times to erase the data from the entire hard drive. How many times to overwrite the data is always an interesting topic of discussion, recommendations will range from 1 pass, 3 pass, 7 pass, up to 30 or more passes. The exact number of times to overwrite the data has changed throughout the years. My advice is to just use the default setting for any of the programs below and fully erase the data. I recommend the following free tools to sanitize or wipe a hard drive of information:

Secure Erase/HDDerase
Darik's Boot and Nuke - a program that can be booted from floppy or CD to completely erase a hard drive
Eraser by Heidi Computers Limited
Active@ KillDisk

If you plan on giving your computer away, selling it, or otherwise disposing of it, please destroy the data on it by using one of the above wiping utilities. For all practical purposes, wiping the drive with one of the utilities above will be sufficient in making sure your data does not fall into the wrong hands.

Degaussing a Hard Drive

An extra step is to degauss the hard drive. Degaussing is a process whereby the magnetic media is erased using a reverse magnetic field to scramble the electronic data and make it unreadable. Unfortunately degaussing machines are rather expensive ($2000.00 or more) and are not realistic purchases for the average consumer. However, you can send your hard drive to a degaussing company like Garner Products or SEM and for a few dollars can have your hard drive completely degaussed and/or destroyed. If your data security is important enough, this is a wise step. A hard drive that is degaussed is rendered useless.

Physically Destroying a Hard Drive

Physically destroying a hard drive is by far the most effective method to ensure the safety of their data. If you choose this method, please wear protective glasses and other gear to keep yourself safe. It can be a dangerous activity that I don't recommend to everyone. Also, as a precaution, wrap the hard drive in a towel so the parts don't fly off and do more damage.

There is actually a Do-it-Yourself kit for physically destroying a hard drive called the Diskstroyer, it comes with all the tools and things needed to magenetically and physically destroy the hard drive.

Whether its smashing the hard drive with a sledgehammer, drilling holes into the drive, tearing the drive apart and destroying the platters, shredding the drive, or other methods your sensitive data will be safe.

For the most security, I recommend doing as many of the above procedures (wiping the drive, degaussing it, and destroying it) as you can. If a drive is wiped, degaussed, and destroyed the chances of recovering the data is almost nil.

Conclusion

If a computer store, consultant, or other qualified computer tech tells you your hard drive is crashed and the data is unrecoverable, ask for them to return the original drive to you. This way you can wipe it clean, degauss it, or physically destroy it and dispose of the drive to your satisfaction and avoid situations like Mr. Bowen's where your data suddenly appears on someone else's computer screen.

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Deleting Hard Drive Data vs. Physically Destroying Hard Drive

What Not To Do

Using Wipe Utilities

Degaussing a Hard Drive

Physically Destroying a Hard Drive

Conclusion

Links to Other Important Information