Alan Cox (alan@lxorguk.ukuu.org.uk) writes:
> > Reading this thread, I see that many have a misconception. Bad blocks
> > will not be found when someone tries to write to a bad sector! As
>
> Actually on IDE and modern SCSI disks they will be. The drive does it for
> you without you knowing. It also schedules its own I/O, it lies about
> geometry and it does transparent block remapping.
Feel free to correct me, but it is my understand that:
- Bad sectors are automatically remapped to another track
- There is a limit to how many bad sectors that can be remapped
- There can be a number of sectors already remapped when you buy the drive new
- There are very few drives out there that are totally error free - if there
were, you'd be paying a lot more for drives
- Consequently, most drives aren't error-free when they come out of the box
Now, the question is, what happens when that remap track gets full? The
drive reports an error back to the OS, and that's where the problem starts. So this idea that "toss the drive if you have one bad block" is dumb, because they *all* have bad blocks, and getting an error on a block is no guarantee that your drive is failing - drives generally have an advertised error rate - and while it's close to zero, it's not zero, and even if it's 10E33, you're going to hit that sooner or later.
-
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This archive was generated by hypermail 2b29 : Sat Apr 15 2000 - 21:00:19 EST