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How to Securely Dispose of Your Old Hard Drives

The hard drive in your PC or laptop holds all of your data and applications. It is kind of like long-term memory for a computer. Just like in the movies, even when you erase that data, remnants are left behind making it often possible to recover the data long after it has been deleted.

How is this possible? Well let me explain how Windows (and some other operating systems) store data on your hard drive. Instead of one giant container, think of your hard drive as being made up of lots of smaller containers or blocks. Each block contains fragments of a single file. As an example, let’s say there is an MS-Word document named “Tennis Schedule.docx” stored on your hard drive, and it is taking up 6 blocks. Windows also keeps an index system which tells it which blocks are being used to hold your Word document. When you delete the document “Tennis Schedule.docx”, only the entry in the index system is removed. The blocks containing the actual document data are still intact. In fact, the blocks will remain intact until Windows decides to reuse those blocks for something else.

You may ask, “why does this matter”? Well, since the file data still exists on this drive the data can often times be retrieved by using sophisticated software or hardware. This means it is possible to take a look at all that personal data on your hard drive you thought you formatted.

Don’t worry; there are some steps you can take to make sure your old data is permanently destroyed.

  • Have your old hard drive commercially destroyed. There are recycling and data destruction facilities with equipment which will literally shred an old hard drive as if it were a piece of paper. With your drive in a hundred pieces it is doubtful that the most dedicated data thieves will have any success getting at your old data.
  • Securely wipe your entire drive. There is software available which can replace the contents of each block with new data. By doing this, the data retrieved should be the last value stored in each block instead of your old data. Active’s Kill Disk (http://www.killdisk.com) has a free version which allows simple hard drive wiping. The paid versions allow for better protection.
  • Drill holes in your hard drive. Drilling three or more holes through the hard drive’s platters (round spinning plates inside the hard drive) at different distances from the spindle (in the center of the platters) will effectively make your drive unreadable. Make sure you use a good drill bit, preferably diamond tipped.

Doing any one of these will help ensure your old data will not be recovered. Whether I’m having the hard drives commercially destroyed, or I’m drilling my own holes, I always prefer to use a secure erase software to replace the data on my drive (for at least a single pass) first.

About the author

Robert Borges

About Robert...

I have been in the IT industry since 1993 focusing mainly in networking. Though I got an early start as an amateur computer enthusiast, and wrote my first database app at age 12, I started my professional career working in the MIS department of one of the largest liquor distributors in the northeast. I started out there as a systems operator on the company’s two mainframe systems. From there I moved into PC support, and help design and implement the company’s first client-server network… This was back in the days of Win NT 3.51. I also worked on my first migration to NT 4.0 back then.

From there I went on to work with Novell 3.x and 4.x along with Windows domains and active directory environments. Working my way up from technician, to specialist, to administrator, and eventually all the way up to Sr. Engineer. I spent many years working for consulting firms, 9 of which I owned and operated my own firm.
Over the years, I have worked with (at an expert level) various versions of: Windows client and server operating systems (including Windows 7 and Windows Server 2008 R2);various virtualization technologies (Hyper-V, Virtual Server, Virtual PC, VMware, etc…); MS-SQL server 6.5- 2008 R2; Exchange 4-2010, and much more.

I am now Director of Information Systems at Bay State Integrated Technology focusing on cloud computing and IT service, with expertise in: IT Infrastructure & Architecture, IT Security, and Cloud Computing platforms & technologies (SaaS, PaaS, and IaaS).

I am in a constant state of learning about new products, and new versions of products. Many of which we end up implementing in lab environments and sometimes for our clients. I have a pretty broad range of expertise and experience. It is my goal to share some of this experience on this blog to help enrich the IT community.

Permanent link to this article: http://www.robertborges.us/2012/04/it-security/how-to-securely-dispose-of-your-old-hard-drives/

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