[TUHS] System Economics (was is Linux "officially branded UNIX")

William Pechter pechter at gmail.com
Fri Mar 17 03:26:52 AEST 2017

Norman Wilson wrote:
> William Pechter:
>   VMS source fiche was very common of sites owned by large corporations.
>   Their IT  staff used it to research bugs... and as sample code for
>   writing their own drivers etc...
> =====
> Indeed, I used the VMS source microfiche to learn how to
> handle various sorts of errors (machine checks, memory
> errors) better in UNIX.  Stock VAX systems at the time
> just crashed on any error, but it turned out that many of
> them admitted recovery: some errors were transient,
> others could be ridden over by disabling some piece of the
> hardware.
> This led to an amusing event on the VAX-11/750 that at the
> time handled e-mail as uucp node research!.  (Its internal
> name on our datakit node was grigg.)  People noticed that
> the system was running slowly.  I checked and discovered
> that the CPU itself seemed to be a bit slower.  Then I
> checked logs and discovered that a week earlier, there had
> been a cache error; my new recovery code had turned off
> the failing half of the cache, logged the error, and forged
> ahead.
> o
> At the next convenient time, we took the system down and ran
> DEC's standalone diagnostics.  (Contrary to the rude stories
> one hears, those diags were in fact pretty thorough.)  The
> problem didn't show up, so we booted grigg back up again,
> secure in the knowledge that if the problem was persistent,
> my code would let us know without crashing.  (I don't think
> it ever showed up again.)
> We also learned to pay more attention to console messages!
> Norman Wilson
> Toronto ON
DEC's later diagnostics were excellent.  They were copied by a ton of folks
including Masscomp and Alliant who wrote frighteneningly similar
diagnostic supervisors.

The thing about that is it had a big impact on servicability for those

1.  They had a large number of Field Engineers in the world with DEC
experience who could
come up to speed quickly.

2.  The diagnostics were easy to learn.

Of course the reason they looked like the DEC ones was that ex-DEC
software engineers
and programmers wrote them.

Concurrent Computer's diags looked very similar to the load and run
stuff of XXDP which
required a lot of knowledge of each diag and it's options.  They were
often called the
"No problem found tape" by Field Service -- because the diags would not
find any issues
and the OS running with full interrupt driven OS's would roll over on load.

On the PDP11 there was XXDP's DEC/X 11 system exerciser... On VMS there was
UETP and just looking at the errorlog output.  The only Unix that came
close to
the VMS errorlog in my experience was the errorlogging on AIX was excellent.


Digital had it then.  Don't you wish you could buy it now!
pechter-at-gmail.com  http://xkcd.com/705/

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