Learn What is Bad Sector in Depth and How to Repair Them

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Hard Disk is a most useful name for all types of hardware used in Computer. There will be the replacement of another device easily without loss of information spending some money. But If Hard disk damaged completely then Data can’t be retrieved after spending money. Hard Disk is a storage memory used for storing information i.e. Audio, video, documents, image etc.

How to find bad sector and repair them

Tracks and Sectors

There is a circular disk in the Hard disk that revolves at a certain speed depending on Hard disk construction/company. It also depends on Device. Disk surface is divided into some ring-shaped tracks which are accessible by read/write arm. Read/write head moves one track to another. Each track is also divided into sector containing a minimum amount of bits usually 512 bytes of the hard drive rather than 2048bytes of CDs or DVDs.

Hard Disk tracks and sectors

Bad Sector: When we store any data into a Hard disk then this operation is called write operation. When we open or copy any files with the help of application from Harddisk is called read operation. Whereas Data is read or written on the sector of the hard disk, it must remain healthy all time. But when problems like a scratch or magnetic pole error occur in this sectors, then Computer cannot read/write on that sector at the right time. These problems increase day by day. Sudden shutting down PC and scratch by injury of the Hard disk(like the CD or DVD scratch) are the main causes for the Bad sector.

The bad sector is of two kinds-

  1. Logical Bad Sector: This is caused by software while reading or writing data on Hard disk such as sudden shutting down, not allowing software to be properly read or write. So, this can be fixed by repairing tools.
  2. Physical Bad sector: When the Hard disk is hit by the big amount of force suddenly, then one or more scratch would be noticed on the disk surface. Scratch damages sector/s badly. This type of bad sector cannot be fixed due to permanent damage.

Why are Bad sectors created?

Logical or Physical Bad Sector happens due to certain reasons that should be taken into consideration while using PC.

  1. Shaking of Hard Disk: It is very harmful to physical sectors especially for Laptops moving from a different dimension. It is a more dangerous problem running PC because read/write head is still moving.
  2. Power supply problem: If proper voltage and current rating are not ensured for Hard disk, it will be a probable condition for hard disk bad sectors. Especially for portable hard disk, sometimes USB cable is so long or problem in USB port causes Bad Sector.
  3. Overheating: If proper air cooler is not confirmed for PC or laptop and PC is running for 10-15 hours long then Bad sector may appear.
  4. Replace/Overwrite: It can cause Bad sector while replacing or overwriting any files repeatedly. After closing all application running currently, restart PC.
  5. Fragmentation: Fragmentation is also a cause for the Bad sector. So Defragmentation should be done regularly.
  6. Virus: Virus is always a flip-flop program that makes computer busy for flip-flop process. So, Hard disk spinning may be faster than normal condition. The bad sector may occur in that case.

Bad Sector Test

There are many tools for testing purposes especially tools of every brand of Hard disk. However, you can assume Bad sectors by some symptoms:

  1. Lately, Computer is running slow or hung almost times. Treatment of slow Computer is not also working. Then you can assume it may have bad sectors.
  2. Blue Screen of Death(BSOD)may appear while running PC suddenly. It is because operating system can’t read important files that were in that bad sector like system files, page files etc. Although BSOD is shown for RAM and driver problems, you can assume probably.
  3. If the computer can not boot from Hard disk then it may have a bad sector on the system drive. It stops showing blank or black screen or showing “Hard disk not found” as well as can’t read files. If Bios detection is not possible due to Bad sectors then this problem may occur.
  4. The hard disk is not found while windows setup or showing the blue screen of Death. PC is restarting again and again. But Hard disk is found using partition tools or DOS(Disk Operating system) tools. Even Windows setup is continuing but interrupts in the middle.
  5. Partition formatting or creation would be interrupted, or PC hang during formatting partition and it’ll not be finished either.
  6. In the case of Physical Bad Sector, Sound can be heard from Hard disk.

How to repair Bad sector:

There are many ways to repair Bad Sectors. Some of them below here-

  1. Repair tools: You can repair bad sector by using repair tools available over the internet. Most popular Repair tools are Check Disk, ScanDisk, Formatting, HDD utility tool (HDD Regenerator, HDAT2 etc.)
  2. If above technic is not successful then with the help of FDISK in DOS mode, the New partition can be created by deleting all partition of the Hard disk. The size of Partition should be small if possible i.e. 10GB, 20GB, 30 GB etc. All partition have to format in DOS mode and must be normal formatting not “Quick formatting”. Normal formatting time is very much larger than Quick formatting time. So don’t stop formatting being bored because it will be harmful to the Hard disk drive.  Now find out which drives are not formatting and assume this drive has a serious bad sector that can’t be repaired.
  3. As a next try, You can do a Low-level formatting to the Hard drive. This is a very strong format which deletes all data of Hard disk permanently and not keeping any tail. No data can be found after doing low-level formatting. Each and every sector is rearranged and zero fill is done in this format. If you are a new user, then you should be very careful to do Low-Level Formatting because entire Hard disk may be damaged if wrong steps are taken. Every Hard disk company creates their own HDD utility software, you should use that utility.You can use universal utility tool to do low-level formatting. My favorite tools are-

Moreover, Every famous company like Samsung, Toshiba, Seagate (Maxtor earlier)  has their own utility tools.


Before doing all the steps ensure first that your PC will not be stopped or shut down during Bad sector repair process otherwise you may lose data permanently.

Final Verdict

In my views, If soft bad sector found, You can perform these steps given above but if Hard bad sector found, don’t do it. Best of all, replace Hard Disk with a new one and copy all data to the new Hard drive. It will be safer for future use. The hard disk has a time limitation. After several years, Bad sector or at least weak sector may be found. Be careful, Don’t lose your valuable data.

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