Path: utzoo!utgpu!water!watmath!clyde!bellcore!decvax!ucbvax!ucdavis!caldwr!kwongj
From: kwongj@caldwr.caldwr.gov (James Kwong)
Newsgroups: comp.sys.apollo
Subject: Re: DSP90/MSD-500 Disk Errors
Keywords: MSD-500, disk errors, disk address 1
Message-ID: <312@caldwr.caldwr.gov>
Date: 17 Feb 88 18:05:15 GMT
References: <8802151918.AA11087@EDDIE.MIT.EDU> <3392@super.upenn.edu>
Organization: California Department of Water Resources
Lines: 58

In article <3392@super.upenn.edu>, adam@hyper.lap.upenn.edu (Adam Feigin) writes:
> Well, I'm starting to suspect that there's something wrong with the
> disk controller (either the multibus SMD board or the drive electronics
> itself) as the MSD-500 was replaced in June with a BRAND NEW CDC drive,
> and yet these errors keep occuring (I'm thankful that Apollo ISN'T
> vanilla U**X, as errors on the first disk address would be disastrous !!)
> When you get these errors, are they at the first address on the disk, or
> are they at various places on the media (We also get errors at assorted
> disk addresses, but the errors at the first disk address happen at least
> once or twice a week) ??
> 
> 						Adam
> 
> ------------------------------------------------------------------------------


We're having the same problem here with our DSP90/Control Data Corp.500 mb. 
storage module except the header errors always occur on vol. 1 addr 1.

A service rep. came out and moved the label to another spot on the 
storage module (ran some kind of fix_vol or something like that) and 
salvol the disk to no avail.

We still get the disk block header error now and then. I noticed that
if I partnered the DSP 90 to a diskless node the frequency of the 
error messages increased from once every several months to once every
few days.

I was told basically the same thing; the problem was probably caused 
by a grounding problem somewhere, that it was common among the DSP 90s 
and that the errors probably occurred when the disk is in a reading 
mode, and not writing mode and as such I should not have to worry too
much about the integrity of the data. 

Still though, I would feel less paronoid if these errors didn't crop up 
now and then. In your case with the errors occuring at different spots,
your assessment of the cause sounds reasonable. I take it that these
header messages (other that vol. 1 addr 1) also refer to the the storage 
module and not the error messages caused by specifying non-existing 
devices on the DSP 90 such as a cartridge drive or floppy drive.

Excerpt from our 'lsyserr':
Friday, December 18, 1987
   3:45:19 pm (PST)  disk error
      storage module, volx=1, daddr=1: disk block header error (OS/disk manager)
Monday, December 21, 1987
   3:14:54 pm (PST)  disk error
      storage module, volx=1, daddr=1: disk block header error (OS/disk manager)


James Kwong  Calif. Depart. of H2O Resources, Sacramento, CA 95802
ucdavis.edu!caldwr!kwongj (Internet) ...!ucbvax!ucdavis!caldwr!kwongj (UUCP)

-- 
James Kwong  Calif. Depart. of H2O Resources, Sacramento, CA 95802
ucdavis.edu!caldwr!kwongj (Internet) ...!ucbvax!ucdavis!caldwr!kwongj (UUCP)
"Our program who art in memory, HELLO be thy name.. "
The opinions expressed above are mine, not those of the State of California or the California Department of Water Resources.