Hard Drive Bad Sectors

I have a few questions on this. My understanding is that having a few bad sectors is not he end of the world. A hard drive can last years (with that said I think it is always a good idea to have two backups of important data.)

Now I have been reading in some places that if you have a few bad sectors then it is an indication that the hard drive is failing and you must buy a new one no matter what, (is this paranoid or an attempt to scare people to make money?) However in other places I am reading, for example here Bad Sector , that having a few bad sectors is normal in many cases.

Quote:

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Hard drives contain millions of sectors. It is very normal for some of these sectors to be bad sectors, even when the drive is first manufactured.

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What are peoples thoughts on this? I have, currently, four hard drives. Three of the four have bad sectors according to the Linux Disk utility. Now two of them, one has 11 bad sectors the other has 22. The third however has -1 bad sector (-1?) The one with 22 bad sectors, the Linux Disk utility had previously told me that it was failing and needed to be replaced. Now with newer versions of the Disk Utility it is all green and fine. It just says a few bad sectors. All my hard drives work fine and I am not seeing any increase in bad sectors let alone a fast and large increase in bad sector numbers.

Thoughts on all of this?

Having a few bad sectors is one thing, but if a drive is continually gathering additional bad sectors, I'd recommend backing up as soon as possible, then replacing the drive. I usually check my own drives with S.M.A.R.T., and with the diagnostics utility provided by the hard drive manufacturer.