Disk Gobble-d-gook

[Chris Lewis]

In article <1839 at wasatch.utah.edu> kessler%cons.utah.edu at wasatch.utah.edu (Robert R. Kessler) writes:

>One of our customers had a strange occurrence that I was wondering if
>anyone else has seen....

>One evening, they were quitting for the day and doing their nightly
>backup.  This is accomplished by getting everyone out of the system,
>doing a shutdown, then logging in as backup and putting in the tape.
>When the tar finished, she pulled the tape out and suddenly the system
>just shut itself down.  Odd.  Anyway, she then rebooted (doing an
>fsck, which she said found lots of problems ...

etc.

We have seen the occasional machine go down when you physically touch the
tape and/or tape drive (or in some cases simply stand up or sit down within
5 feet of the system).  We call it the "stand up, sit down, crash, crash, 
crash" crash ;-{

In our case, the system behaves *EXACTLY* as if you had hit the reset button.
Memory tests, Wangtek tape drive resets, the works.  (this is AT-style 386
by the way)

At least in our case, this appears to be related to static discharges.  If
you took a static hit while the disk was writing or something like that,
your disk could be severely scrambled - eg: zaps in the superblock or inode
table.  Depending on how bad it is, fsck may not be able to recover anything
sane.

We've been able to (cross-our-fingers) completely eliminate this problem
by:

	- make sure that every internal peripheral has a ground strap.
	  (yeah, I know, the manufacturer doesn't think these are necessary
	  any more, but their machines are crashing)
	- make sure that every external connector that has a metal shell
	  is firmly grounded.  (In our case, the COMM port studs didn't
	  make electrical contact to the chassis, so we put star washers
	  under 'em).

I assume that your PS-2/80 is probably okay w.r.t. the above, but you may
want to check into the grounding of other things like the multi-port boards.
-- 
Chris Lewis, R.H. Lathwell & Associates: Elegant Communications Inc.
UUCP: {uunet!mnetor, utcsri!utzoo}!lsuc!gate!eci386!clewis
Phone: (416)-595-5425