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Why does an HDD get bad sectors? Do they corrupt data?

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Bad sectors are small clusters of data that cannot be accessed on your hard disk. Moreover, if they increase over time, it will cause stress to the reading arm of the HDD, which in turn may cause physical harm to your HDD. Such physical failures are termed as catastrophic, and an HDD cannot recover from them.

A sector is just a unit for storing information. Your HDD stores things in ‘ sectors instead of creating a pool full of floating data. The international standard of a sector is 512 bytes.

Bad sectors occur with the ordinary use of computers and in a world full of defects are relatively prevalent; however, it is possible to take several easy measures to prevent and fix small HDD bad sectors. Bad sectors don’t help in improving software efficiency.

Types of bad sectors

There are two types of bad sectors: hard and soft.

Hard bad sectors are the ones where the HDD is physically harmed, which may occur because of a collision in the head, or in a set magnetic state. A ‘hard bad sector’ could be created when your machine is pushed or aggressively moved while the hard disk is scanning information, or is subjected to intense heat, or has a defective mechanical portion that allows the head to touch the disk surface. Hard bad sectors cannot be fixed but can be prevented.

Soft bad sectors happen when the sector-related error correction code (ECC) does not match the sector information. It is a logical failure and not a physical one. Viruses and other malware can also cause soft bad sectors by unexpectedly accessing your hard disk. These can be fixed by overwriting the entire hard drive or hard formatting it to zeros.

Also read: Is partitioning your Hard Disk Drive (HDD) a good idea? Pros and Cons

4 reasons why an HDD get bad sectors?

Why does an HDD get bad sectors? How to check for them?There are various reasons why an HDD gets bad sectors, and we’ve listed four below:


  • Overheating: Overheating is one of the leading causes that can internally damage an HDD. Usually, HDDs work perfectly in a temperature range of 20-25℃.
  • File System Errors: Error in the file system may cause weak hard disk areas. When your file system is affected, logical mistakes could happen and eventually cause bad sectors on your hard disks.
  • Improper Shut Down of PC: Hard disks are usually operating in a high-speed condition when in use. And the drive head remains in various places on the disk to read information. So the device head will be forced to come back to its initial condition if you stop your computer unexpectedly. And the device head can brush against the computer in this phase, which may contribute straight to bad sectors caused by friction. You should, therefore, make a practice of correctly turning off the computer.
  • Dust and Static Electricity: Dust is one of the biggest causes of hard drive failures. Accumulation of dust in and around the drive can cause bad sectors. Also touching or handling the HDD without sufficient knowledge can induce static electricity between you and the HDD and in-turn damage your disk. Use anti-static bags or gloves to handle any computer component.

Also read: Master Boot Record (MBR) vs GUID Partition Table (GPT): Which method to use for your SSD

How to check for bad sectors or HDD errors

A tool called “Chkdsk” has been included in Windows. It is advisable to run this tool every once in a while. You scan the drive for disk errors, logical errors, and detect malfunctions so Windows won’t attempt to use the bad sectors anymore. This process, however, requires a lot of time to complete depending on the type and size of the disk.

To access Check Disk, follow the steps mentioned below:

  • Open My Computer from your desktop or start menu.
  • Select and right click on the disk you want to check and open Properties.
  • Select the Tools tab and click on Check Now.
  • A dialogue box will open prompting to start the process. Click on Start. You may get a message saying that Chkdsk wants exclusive access to your hard drive, click on OK.
  • Restart your PC.

Can bad sectors corrupt the data of your entire HDD?

No, bad sectors will not corrupt the data of your entire HDD, but they can accidentally corrupt the part of it that is important and can cause an immediate disk failure. Having a bad sector on your HDD puts your data at risk perpetually. It is best advised that you backup your HDD as soon as possible if you detect a bad sector.

Also read: What does the ‘Defragment and Optimize drive’ app on Windows do?

Rajiv Kulkarni

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