How does bad sector reallocation work?

WD Internal Drives Desktop & Mobile Drives
1

Hello,

I would like to know briefly how the process of reallocating bad sectors works.

Does an hard drive identify (and reallocate) bad sectors directly during write operations, or is a previous read operation required to determine that the sector is bad?

Does it happen like this:
Read operation > if the sector is bad it is marked as “pending” (in SMART) > the next time the pending sector is written, it gets reallocated.

I was curious to know what happens when data is written to unused space: if a sector is bad, should data get reallocated at once, or will the hard drive not recognize the bad sector, and thus the written data will be corrupt?

Thanks.

2

Hello, as far as I know sectors only get relocated when a write operation fails, most of the time a read operation will only give a I/O Error. If the data is to be written in a bad sector, the sector should be reallocated, however as you mentioned if a sector with data gets damaged the information will be corrupted.