Thanks for your responses and help.

From: Manuel Bouyer <bouyer@antioche.eu.org>
Subject: Re: kern/14007: uncorrectable data error reading fsbn -- problems with IDE hard disk
Date: Wed, 19 Sep 2001 22:29:01 +0200

...

> > BTW, both hard disk are IBM hard disks and the machines I tried 
> > this on are ThinkPads (600E and X20).
> > 
> > I hope someone else can reproduce this but searching the archives
> > and pr forms didn't turn up anything for me.
> 
> Well, your disk is obviously dead.

That may be true, but it's been two disks for me in rapid succession
on two different machines with two different power supplies, and I'd
like to figure out how to avoid toasting further disks -- not to
mention getting a stable environment back ;-)

In case I presented the sequence of events poorly, here's another
attempt:

1) Problem occurs on ThinkPad X20 w/ an IBM hard disk.

2) Suspecting the problem was with the hardware, I did a fresh install
   of 1.5.2 on a ThinkPad 600E with a completely new hard disk (also
   IBM) and a different power supply.

3) After installation on the 600E, I put the old hard disk in the
   extra bay to do a data transfer -- I transferred my /home directory
   (which when done using bulk methods failed, but copying individual
   files interlaced w/ syncs did work) and /usr/pkgsrc.

4) Then I built and installed some packages on to the new hard disk.

5) Some time afterwards, when trying to work on some packages in
   /usr/pkgsrc, I started getting the problem on areas of the disk
   which had been used to build and install packages earlier (but
   also other areas, so far only located in /usr/pkgsrc).

BTW, both machines were sitting on desk surfaces when the problems
were noticed and I almost always have the power supplies plugged in
(and the batteries are nearly always close to fully charged).

> Now, the problem is to find why it died. 

Yes, I'm very anxious to do this.

> Does it get enouth power ?  Doesn't it get too hot ?

How can I determine the answer to these questions meaningfully?  FWIW,
I don't particularly notice the machines getting hot.

Should I disable Ultra DMA on any new disks that I use?  If so, is it
enough to recompile a kernel w/ the following sorts of settings?

  wd* at pciide? channel ? drive ? flags 0x0fac

[ Is there some way to change this setting dynamically?  May be using
the kernel debugger? ]

> It's quite possible that windows won't push it that hard.

That's possible.  Ah, you mean and that's why the problem may not have
been noticed more widely?