[pups] Strange problems on an uPDP 11/53+

Martijn van Buul pino at dohd.org
Tue Feb 6 17:39:28 AEST 2001

Steven M. Schultz wrote:
> Hi -
> > From: Martijn van Buul <pino at dohd.org>
> > After 52 days, my uPDP 11/53+ has suddenly been acting rather strange.
> > /usr/include got 'replaced' by /usr/new, to be precise. At the time,
> 	Oops!   

Well, strange things are afoot indeed. About the same time, 1 machine
crashed (A DEC Alpha running OpenBSD), 2 started acting very strangely,
and had to be rebooted (My PDP, and a Wintel box running Windows 2000),
and a 4th machine (A Wintel box running Minix-VMD) suddenly had some
problems reading his harddisk and using its network (but recovered). The
strange thing is that these machines aren't related in any way but one:
they're standing quite near to eachother. Do I hear EMC somewhere?

> > Any hints?
> 	How much memory is on the system now after the reboot.

1.5 MB. 798 Kilowords. 

>       The only thing that pops into mind is that the system is running
>       without enough memory.    If part of the memory on the system dropped
>       out earlier that would (possibly) explain the strange behaviour was
> 	seen.   Rebooting/reseting the system would cause the system to
> 	recount memory.

Well, the machine had 1.5 MB before it crashed.. It's doubtlessly some
memory fault, but it *seems* to be a temporal one.

> 	"sysctl hw" will give several lines of output - the two you'd be
> 	interested in are 
> 	hw.physmem = 2097152

hw.physmem = 1572864

> 	hw.usermem = 415744

hw.usermem = 313472

> 	'physmem' is the amount of memory physically present and 'usermem' is
> 	the amount current free and available for user programs.

Should be enough. 'cc' works without problems - only my ps with debug
info seems to be affected; it might not be a memory issue, but a "ps can't
determine the right amount of processes"-issue.. 

I've checked it, and this seems to be the case. Ps thinks that there are
0 processes running, and does a 
 outargs = (struct psout *)calloc(nproc, sizeof(struct psout));
on that. With 'nproc' being 0, this returns a NULL pointer, but doesn't
mean that the process is out of memory.

Having no ps is very annoying; finding back those 4 children spawned
by a httpd can be a nuisance then. pstat -p works, but it isn't comfortable:)

> 	"pstat -s" will give a swap space usage summary.

15/59 swapmap entries
910 kbytes swap used, 6263 kbytes free

    Martijn van Buul -  Pino at dohd.org - http://www.stack.nl/~martijnb/
	 Geek code: G--  - Visit OuterSpace: mud.stack.nl 3333
   Kees J. Bot: The sum of CPU power and user brain power is a constant.

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