Favorite Head Crash (was Re: modern removable media drives)

From: Bill Sudbrink <bill_at_chipware.com>
Date: Mon Nov 16 14:55:49 1998

> > units. Every minute or so, one of the drives would
> > puff out a small orange cloud. I was told that each
> > puff was a head crash. The drives would expel the
>
> Not a real headcrash (because IMHO that implies the heads don't take off
> again), but more like HDI (Head-Disk interference). This can, indeed, be
> non-fatal - in fact some hard disks are designed so the heads hit the
> surface when they load and then fly from there. It always worried me, but
> it seems to be OK.
>
> On the other hand, if each drive experiences HDI at 3 hour intervals (on
> average), then I would suggest there's something wrong. Possibly they are
> in need of filter changes or something.

Hmmm... maybe once a minute is a little exaggerated. We probably stood
there for 15 minutes and saw two puffs.

>
> > orange oxide that had been scraped from the surface,
> > the head would almost always be undamaged and the
> > drive would keep right on going. The bad blocks
> > would be noticed and marked by the OS and when a pack
> > had enough bad blocks it would be pulled and sent out
> > to be resurfaced.
>
> Minor HDI doesn't even cause bad blocks...
>
> But the idea that bad blocks are continuously being created and then
> ignored by the OS also worries me. What if there's some important data
> there that needs to be read back. Of is this a WORN (Write Once, Read
> Never) system :-)

I don't know. I'm not even sure what kind of machine was driving them
(although I believe it was IBM). I was hoping someone who worked at SSA
Baltimore might pipe in.
Received on Mon Nov 16 1998 - 14:55:49 GMT