[Techtalk] bad blocks

[R. Daneel Olivaw]

Hi again,

> >It occurrs, because of the small size, that some parts loose their
> >ability to store magnetic information. Therefore, some 'blocks' are
> >bad, after a number of read/write cycles.
> >
> There is yet another reason. Because we are talking moving parts, it
> can  happen that the tracks start wandering. This can be seen by
> getting bad  blocks on a track (cylinder) order. This happens because
> positioning is  - though very accurate - still something with an error
> margin. And at  times that margin works out wrong. Some drives are
> more sensitive to  this than others. When this happens, the bad blocks
> can sometimes be  recovered by writing to the complete tracks, and
> that way "resetting"  the track location signals on the platter. On a
> SCSI disk with this  problem, giving the low level SCSI format command
> will also solve this.

I fully agree, and would add that some motherboards used to have low
level formatting utility built-in that permitted such an operation on
EIDE drives. Besides, I remember some hard drive manufacturers providing
a low level format utility, run from DOS.
I however would rather trust the mechanics of a hard drive, than
the physical magnetic layer consistency.

good night everybody (well, at least, it's night here :p)

R. Daneel Olivaw,
The Human Robot Inside.