Sys V terminals lock up

[John M. Ritter]

[ *** ]

Well, here's my tale of woe...

I have a VAX 11/785, running System V 2.0v2, 3 RA-81 drives and 3 RA-60
drives. Also, there are 10 DZ-11 boards (count 'em) for 80 terminals and/or
printers. As there are RA drives, there's also the whole DEC UDA-50 mess.

The problem I have is, at irregular intervals, the system decides to lock
up some terminals. Whenever the terminals go, the always go in groups of 8,
so I can identify a single DZ board. Well, it's never the same board. The
ones that go may have anywhere from one to eight users at the time.
Naturally, all hardware passes all diagnostics test.

The processes on the system continue: even the users on the locked up
terminals are shown as active, although ALL their jobs just hang. It is
impossible to kill any of these user processes.

The only (fairly) consistent thing throughout this problem is system usage.
Although the number of users vary, (10 - 25 average through the day) the
system maintains a consistent level of usage: normally 70% usr, 30% sys,
0% waiting for i/o, 0% idle. We manage to keep it pretty busy all day
long.

Any ideas what could be causing this problem? If it were an intermittent
problem, I wouldn't be overly concerned, but I find myself re-booting the
system AT LEAST every other day.

All help and suggestions are greatly appreciated. Please reply via mail,
and if I ever get this thing figured out, I'll post the results.
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"I enjoy working with human beings, and                         John M. Ritter
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 {bellcore,bunker,cuuxb,harpo,ihnp4,infopro,mergvax,princeton,sys1}!motown!jmr
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