bad sectorss

[mrintech]

dear friends

will any one from you will plz tell me what are the various causes of bad sector on a hard drive?

[pimpom]

The main causes are -

1. Power failure or fluctuation, especially when you're accessing the hard disk, i.e., if you're reading or saving some data when the power fails.

2. Mechanical shock, especially while the computer is running. HDDs can tolerate more physical shock when power is off than when it's on.

3. Virus. Some viruses can create what appears to be bad sectors.

[AlienTech]

Modern hard drives do not have bad sectors. These are hidden and remapped to unused sectors on the drive. But if you run out of spare sectors the drive will have problems. The only way to develop bad sectors is for the drive platters coating to become loose somehow. Mainly by sticktion. When the drive gets too hot the oil changes form and then when you shut it down, the head picks up these oil and it is actually gunk and becomes as hard as super glue and gets stuck to the drive platter. So when power is applied a lot of force is used to turn the platter while the head is stuck to it with this gunk. Sometimes, the magnetic material comes loose and you develop bad sectors there. But since this area is not used to store data the problem is this particles fly around and gets stuck at some place else and then you develop bad sector problems.
IF a large patch of material comes off then you have problems even booting the drive since it usually takes out your fat and boot areas.