By: Alexander G. Chamandy, Managing Member, Envescent, LLC

February 26, 2015 7:55 pm EST

Four dreaded words.

“My hard drive crashed.”

For the average computer user, we often don’t understand why it happened, but we live with the catastrophe of the aftermath. Files and data often irretrievably lost and years of information evaporate in what seems to be blink of the eye. But often the warning signs are apparent, long before a hard drive becomes a total loss. It starts with bad sectors.

Data recovery technicians are no stranger to hard drives with bad sectors.  In fact it’s one of the more common forms of hard drive damage that we see from consumer storage devices.  So what exactly are bad sectors (or media errors) and how do they affect a hard drive? Knowing some of the rudimentary answers to these questions can help you anticipate problems with your own computer and act before it becomes a crisis. That is the purpose of this article – to arm you with knowledge before you potentially experience a hard drive loss yourself.

What is a hard drive sector?

Let’s start with the basics.  Hard drive sectors hold tiny chunks of information.  Each sector is just a small section of magnetic media on the surface of the hard drive.  This surface is referred to as the platter of the hard drive.

Data is broken up and physically stored across a hard drive’s sectors. For older drives, each sector will hold up to 512 bytes of information, and on modern drives they are 4096 bytes in size.

Your actual data, such as documents, photos and music, is broken up and stored in multiple sectors as a collection of fragments.  When these stored data fragments are reassembled properly, your data is accessible to read, edit and save.  But when any of these fragments of data cannot be accessed properly, it may be due to bad sectors.  And those bad sectors may actually get worse as the drive is repeatedly used.

How do hard drive sectors go bad?

Most of the time hard drive storage sectors go bad because of wear and tear. Hard drives spin around from approximately 5,400 RPM up to 15,000 RPM, depending on the make and model of the drive.  This centrifugal force, combined with the heat of the motor and the action of reading and writing data all cause the hard drive to begin to stress itself on a molecular level.

The surface on which that data is recorded is a microscopic layer of magnetic materials that is electroplated onto the hard drive’s platter.  It is quite fragile and can actually begin to degrade or even flake off over time into tiny bits of metal.  Sectors may also degrade due to direct physical damage, manufacturer defects or other problems.

A sector is considered “bad” when it takes too long to access, becomes no longer readable or writable, or otherwise becomes compromised. Because bad sectors are a sign that a hard drive is failing, it is recommended that a hard drive should be retired as soon as the number of bad sectors become significant. Once bad sectors start to develop, a hard drive will functionally deteriorate over time until it is no longer operational.

How can I avoid bad sectors?

You can’t reliably avoid bad sectors, but you can try to protect yourself by keeping your data on multiple storage devices, so that when (and not if) your hard drive dies, you have a copy of your data located somewhere that is still reliable (and from where you can recover your files).  To ensure that your hard drive has a long, healthy life, you can be mindful of avoiding extreme temperature changes, high humidity, physical shock and excessive movement while the hard drive is powered on.

If I didn’t backup, is my hard drive’s data permanently lost?

Even if you don’t have a copy of your data stored elsewhere when a hard drive fails, don’t lose hope! There are methods that an experienced data recovery expert can use to pull files from damaged hard drives. Prices and vendor diligence widely vary across those who claim expertise in this area. Find a resource who will exhaust every option to re-unite you with your data and won’t take advantage of you in what they charge during what will usually be a stressful situation.


Hard drive designs are a magnificent technical achievement for storing your data and they are continually being improved. However, most hard drives inevitably will wear out with use, often evidenced by bad sectors. If you keep aware of this possibility and keep on the lookout for the warning signs, your computer technical resource can help you minimize the impact of this recurring issue on your life.

The views and opinions expressed herein are those of the author(s). Core Compass’s Terms Of Use applies.

About the author

Alexander G. Chamandy is a seasoned information technology professional with more than two decades of experience in the industry.  He is a managing member of Envescent, LLC, a business IT solutions provider serving the Washington, DC area.

hard drive sectorscomputer hard drives
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