Subject: Re: kern/10430: Wd driver cannot handle bad144 table properly?
To: Greg A. Woods <>
From: John Hawkinson <jhawk@MIT.EDU>
List: netbsd-bugs
Date: 06/24/2000 14:43:17
It is unreasonable to expect automatic bad block mapping
of drives to work reliably in all cases:

   a)	  bad-block maps can fill if disks are very bad. It is
          still desirable to be able to use NetBSD on those disks,
	  and bad-block mapping should be possible at a higher layer.

   b)	  bad-block mapping by the hardware is transparent and there is
	  little visiblity into it. When it fails (i.e. one continually
	  gets read errors on a given block), it is hard to know if the
	  bad-block mapping is broken, or if a) is in force, or some
	  unknown. Again, it is desirable to be able to recover from
	  this case.

   c)	  "Trust no one"; "Be liberal in what you accept and consrevative
	  in what you send."

bad144 should work in all cases, for these reasons.

  (who has had to use multiple nested ccds to make "holes" in his IDE disks
  to avoid bad blocks because 1) bad144 didn't work 2) the drive did not
  auto-remap, and is therefore bitter.)