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From: Robert Eckardt <roberte@mep.ruhr-uni-bochum.de>
Message-Id: <199610312031.VAA00837@ghost.mep.ruhr-uni-bochum.de>
Subject: Re: server death when swap space is all gone.
In-Reply-To: <29680.846740897@orion.webspan.net> from Gary Palmer at "31. Oct. 96  0:45:21"
To: gpalmer@freebsd.org (Gary Palmer)
Date: Thu, 31 Oct 1996 21:31:06 +0100 (MET)
Cc: robh@imdb.com, freebsd-questions@freebsd.org
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> > A couple of time now I've seen Freebsd (2.1.0 and 2.1.5-STABLE) collapse
> > into a smouldering mess after user processes consume all available swap space.
> > 
> > A web server went belly up last night because of this.
> > Why can't the OS recover from this ?. The memory hungry processes die
> > off eventually, but instead the machine locks up and needs to be rebooted.
> 
> I'm curious to hear this ... I often run my workstation out of memory
> (too conservative on swap allocation) and NEVER have a lockup
> problem. Same with the news box, which sometimes runs out of memory
> for some strange reason.

I also experienced mysterious lockups.

Running 2.1.5 on 16MB with 80 MB Swap, I was almost always short of
memory (after a few days uptime). When some jobs required more memory
(Netscape, Reduce, ghostscript) it caused several times one of the
first processes to be killed -- which was usually Xserver, xdm, ...
(I think so.)

Thus, sometimes I would find the video card messed up (having to reboot
blindly), sometimes I would find myself in text mode (but everything
else was also killed :-( :-( ).

On other occasions the machine was simply irresponsive, only hitting reset
or power cycling would help. (the X-screen was simply frozen)
I think something else must have been killed.
However, maybe something else caused a panic and I was dropped to the
debugger, which was "hidden" under the graphics screen ???
(How do people handle panics under X with debugger compiled in ?)

Now I'm using 100MB swap and add sometimes a 40MB file on a DOS partition
as swap. No problems since then, as I keep an eye on swap now.

Hope, this description gives an idea.
Any suggestions ?


Robert

-- 
Robert Eckardt                \\ FreeBSD -- solutions for a large universe.(tm)
RobertE@MEP.Ruhr-Uni-Bochum.de \\       What do you want to boot tomorrow ?(tm)
http://WWW.MEP.Ruhr-Uni-Bochum.de/~roberte
For PGP-key finger roberte@gluon.MEP.Ruhr-Uni-Bochum.de