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Repairing a Bad Sector on Your Hard Drive

written by: D Lamberti•edited by: Simon Hill•updated: 10/22/2011

Have you ever wondered what bad sectors are all about? If they scare you and you want to fix them, or you just want to know more about them, then read on.

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    What is a Hard Drive Sector?

    Hard Drive 

    Before going into the whole process of repairing bad sectors, it is better to discuss some general information that will help you understand the nature of this issue.

    A sector is a very small area on the surface of your hard drive and is also the smallest storage area on it. Each of them stores a fixed amount of data, the standard sector size has been 512 bytes, but some newer hard drives on the market are using larger sector sizes. In fact, according to some internet sources, manufacturers will implement 4096 bytes as the new standard sector size.

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    What is a Bad Sector?

    Since a hard drive contains millions of sectors, it is actually normal some of these turn out to be bad sectors, even if the hard drive is very new. Generally, a bad sector cannot be used due to permanent damage such as physical damage to the disk surface.

    When a bad sector occurs, the data in those sectors may be lost, but keep in mind that other data will be unaffected by it. They can't be repaired, but they pretty much can be avoided by marking them as unusable. Once we do this, the operating system will not attempt to store any information in the identified bad sectors.

    Keep in mind that modern hard drives actually come with many spare sectors which are used to replace bad ones. When the firmware of a disk controller finds one, it remaps the local sector to a different physical sector. So in theory, if your SMART is working, you are safe from random bad sector appearance.

    However, if they are caused by a faulty hard drive - then we are in some serious trouble.

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    How to Repair a Bad Sector

    Now, first of all, I remind you again that in case your bad sectors are the result of some physical damage, this can't be repaired, you won't have your sector back. But as we discussed above, you can 'cheat' and mark that sector as unusable and then the operating system will ignore it.

    Since I have no idea what operating system are you using, I will try to generalize the fixing process.

    1: Open up Windows Explorer or My Computer so you can see your partitions. Right Click one and select Properties.

    2: Click on the Tools tab, you will see Error-checking, Defragmentation and Backup on the most modern systems. What we need is Error-checking.

    3: If you are running Vista or Windows 7, and you probably are, check both options - Automatically fix file system errors and Scan for and attempt recovery of bad sectors. Now run the scanner.

    Manually this can be done from the Command Prompt with the CHKDSK and I suggest you to run it with the 'R' attribute, in other words CHKDSK /r.

    This is also not the very best method to get things done. However, the other techniques require you to be generally more experienced. When you mess up with hard drives, sectors, clusters and partitions things can go bad really easily.

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    Recovering Bad Sectors - Some Personal Tips & Tricks

    Assuming that you are a bit more tech savvy and you know what you are doing, there are a bunch of software products that do a great job when it comes to hardware damage. They work without the operating system interfering, the so-called low level. Some of them are very slow, but they really get the job done.

    HDD Regenerator - One of my favorite products, according to its authors it manages to recover a lot of physical damage on your hard disk. It runs slow but it's great for recovering information.

    SpinRite - A powerful tool for scanning magnetic data storage devices, recovering data and refreshing their surfaces. It also attempts to recover lost data from hard disks that might not be readable via the operating system. However, this software is rather complex and you really need to know what you are doing.

    In addition, keep your laptops and desktops stable, don't throw them around and be very careful if you are transporting them. When reinstalling your operating system it is better to use the normal format rather than the quick, this might help you fix some small problems. Check the SMART status with the right software so you can always be ahead of the problems. If you are doing very important tasks on a computer, best thing to do is to backup your information more often.

    And please, do not download random software from the Internet that matched your Google results, if you are not sure what it does, and what you do, leave it.