What are bad sectors?

by Jane / Mon Dec 18 2017 / UPDATED in Disk Surface Test

What are disk sectors

Before we go to bad sectors, it’s better to know what sectors are.

You might have seen the platter in the hard drive box and the following image is what is on the hard drive platter:


Disk Structure:

  • A Track
  • B Geometrical sector
  • C Track sector
  • D Cluster

This image is from wikipedia , you can read more from that page, history sectors versus blocks, zone bit recording and advanced format, or you can try to understand it like this:

A sector is a tiny cluster of storage space

Bad Sectors

When sectors become bad, they can not respond to hard drive read and write requests, which may result in slow operating speed, unexpected clicking noise or even system crash.

There are two kinds of bad sectors: the physical damages ones, also known as the Hard bad sector, and the software damages ones, called Soft bad sectors.

Both Magnetic hard drives, like HDD and HHD, and solid-state drives, SSD can have bad sectors

A bad sector on a hard drive is simply a tiny cluster of storage space — a sector — of the hard drive that appears to be defective. The sector won’t respond to read or write requests.

There are many reasons to cause bad sectors, which will be in the next post.