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How To Check Your Hard Drive For Bad Sectors And Avoid Data Loss

Updated on April 2, 2013
Picture showing the parts inside a hard drive
Picture showing the parts inside a hard drive

Hard Drives And The Need For Back-Up

Your computer system stores data in your hard drive; everything you save in your system, including documents, music files, video and programs, are stored in this device. It is obvious, as a result, that a possible problem with your hard drive can eventually inflict data loss and even though many companies or specialized software brag that they can recover your files, it sometimes is too expensive and too hard - at times, even impossible.

They say that your data is as valuable as your last back-up; and this saying is absolutely true. For data that we cannot afford to lose, it is advised that we back-up regularly, in multiple means of storage - ideally on CD/DVD, USB flash drive, and on another hard drive (maybe an external one). Some might reach to the point of advising an additional method, cloud storage; personally I would only choose that way if my files are not personal and private. After all, they would be stored on another system to which I do not have physical access and I cannot be sure that other people won't have access to them.

The Bad Sectors Problems

Failures in hard drives have much to do with what is called bad sectors; these are sectors of the drive which have been corrupted or permanently damaged and are inaccessible. Essentially, the data which were stored in those sectors are inaccessible too. The more bad sectors a hard drive has, the more problems it will cause. Frequent freezes, unwanted restarts and crashes, even Blue Screens Of Death (BSODs) can all be a sign that the hard drive is showing some serious problematic behavior. Of course, all the mentioned system problems could also be caused by other hardware in a computer system, such as CPU, RAM, motherboard problems or others, software related.
Troubleshooting your system for possible RAM problems has already been covered here.

This time we will show how we can troubleshoot a hard drive, to test its condition and prevent future data loss.


HDAT2 is a powerful tool which can be used to scan hard drives for bad sectors; it also states that it can attempt to fix the bad sectors it finds, but it is rather hard to manage to repair a hard drive which has many bad sectors. Either way, it can offer a great help to people who want to find out what is causing issues with their system; if a hard drive is checked and found to contain bad sectors, it is probably the culprit. Depending on the amount of the bad sectors it contains, it could be used for some time (with more frequent back-up) but will eventually need replacement.

HDAT2 is included in a must-have programs assortment called Ultimate Boot CD (UBCD).

This CD - which can be downloaded for free as bootable ISO file and recorded on CD or USB flash drive- brings to you a large variety of programs which will, at some time, be useful to you. With it you can scan your hardware for malfunctions, stress test your CPU to ensure its cooling is sufficient, boot to alternate systems and many more. All you have to do is have your system boot from the device you recorded UBCD onto; you will come across UBCD menu list, from which you can reach all the programs.

While you are free to check around all programs in this list, at the moment we will show how HDAT2 can be ran.
To start with, it is located in HDD option, along with other programs that offer similar functionalities. When you choose it, you will need to type "hdat2" to go on with the program.

Devices list from HDAT2. Picture taken from the application's website at
Devices list from HDAT2. Picture taken from the application's website at

Examining Your Drive With HDAT2

The first screen will show the devices in your system; if you have more than one hard drive, or if you also have optical drives such as CD or DVD-ROMs, they will all be listed here, along with some information about them (LBA, capacity for the hard drives and the type of the device). You need to select the hard drive you want to examine, then press Enter.

Menu options inside HDAT2. Picture taken from the application's website at
Menu options inside HDAT2. Picture taken from the application's website at

Menus And Options

THe main menu of the program shows what you can do with HDAT2 on the selected drive. There is a list of tools that allow particular settings of the hard drive to be altered or other kinds of options, such as enable and check SMART, change the security settings of the drive, wipe device etc.

Since we are interested in examining the drive and attempting a repair of bad sectors (if found) we need to follow Device Tests Menu> Check And Repair Bad Sectors. Press enter after selecting this option.

The hard drive examination screen - picture taken from
The hard drive examination screen - picture taken from

Testing The Drive For Bad Sectors

Examination of the drive will begin as you are presented with the testing screen; at top part of the screen there is some generic information on your hard drive. The center part of the screen has a bar which indicates the total capacity of the drive. The "cursor arrow" which shows the current part of the drive that is been examined starts at the left side and finishes at the right side. As the arrow moves to the right, the bar changes colour to blue if the drive has been found healthy; if a bad sector has been found, the computer case speakers will ring, and at that spot of the bar a red B sign will be created, as the cursor moves forward to examine the next sectors. If a suspicious or worrying part of the hard drive has been identified, the spot will be covered with yellow colour and a W letter.

As the examination of the drive continues and finishes, you will have a coloured bar; the blue parts indicate a healthy drive, the yellow are sectors which might get damaged soon, and the red are bad sectors. The findings will also be noted below the bar, with the number of Warning points and the number of bad sectors. The program will also note if it has managed to repair some bad sectors; however, do not feel too secure if you are shown that all the drive's bad sectors have been fixed. It is really hard if not impossible to correct physical damage on the drive, so most probably the problem still exists - at least you now know there is a problem and can take measures against it, such as buying a new hard drive (I suggest getting a fast SSD which is the latest technology, with no moving parts and promise higher performance and reliability).
You can opt to re-run the test, if you feel like it; this way you will find out if the bad sectors were really fixed or not, too.


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    • Viss profile image

      Vishal Chaudhary 

      4 years ago from New Delhi, India

      Very nice article written but sometimes inspite of taking lot of care, hard drive detect bad sectors. So, best way is to keep the back up of the data.

    • ib radmasters profile image

      ib radmasters 

      5 years ago from Southern California


      So true.

      I wrote and managed firmware for a tape backup company before moving onto the disk drive world.

      The only people that backed up anything with the backup product were the IT people. We didn't need any stinkin backups.

      So, we are the problem, I know better but...


    • CyberFreak profile imageAUTHOR


      5 years ago

      Totally agreed... as I had stated in the text, a drive with bad sectors is already a goner, even if it eventually lasts for a couple of weeks or months. Back-up is necessary and must be frequent too; but at least someone can have some peace of mind if HDAT2 indicates no bad sectors found.

    • ib radmasters profile image

      ib radmasters 

      5 years ago from Southern California

      When you have a drive with that many bad sectors, it is time to save what you can and bail.

      Disk drives come with a defect management scheme. It starts at the factory, and then there is reserved locations for find bad sectors and redirecting them to the reserved location.

      There are unrecoverable and there are recoverable sectors. This has a lot to do with servoing, and the firmware, and servo code will try to find where the data has moved. There are retries, and if it recovers it is a soft error, if not it is a hard error and the code will replace that sector with another one in the reserved defect area.


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