Server overloaded? Or is it a bug?

[Daniela]

On Tuesday 03 June 2003 21:55, Erik Paulsen Skaalerud wrote:
> > > Did you try looking at its console?
> > > It probably have lots of pretty messages of whats going on..
> >
> > Can't look at the console. It hangs completely.
>
> Hm. If its running X on the console, have you tried forcing it to a vty?
> (ie, alt+f2 or similar). If that doesnt work, I really dont know what to
> say but to reboot it and see if you are lucky, -maybe- "dmesg -a" have some
> errors in it from the failure. Or maybe /var/log/messages. It depends on
> what the failure was really.

I just rebooted, but there are no messages.

About one minute before the crash, when I wasn't able to run any more 
programs, I looked at the console (nothing special there), tried to login on 
ttyv6 (could enter the username, but no password prompt) and went back to X.
There I tried to find out what has happened.

The cd command was working as expected, but top and ps (for example) did just 
nothing. When I opened a new terminal session, it showed up, but I didn't get 
a prompt.

> > > > I don't have much running, just KDE with about 10
> >
> > programs on each
> >
> > > > of the 16 desktops, and a few background processes. This
> >
> > seems much,
> >
> > > > but I often have much more stuff running, and it is not even slow.
> > > >
> > > > It does respond when I ping it, but won't let me in over SSH. The
> > > > processor doesn't sound busy, so I suspect that the scheduler has
> > > > gone away, or there is some bug in the kernel, or some
> >
> > system table
> >
> > > > is too small.
> > >
> > > Hm. What kind of sound does a busy CPU make? :-)
> > >
> > > > How do I find out what the problem is? (Never had any
> > > > before.)
> > >
> > > Yeah, attach a console and find out whats going on.
> >
> > How can I do that?
> > It doesn't respond to ctrl+alt+backspace and ctrl+alt+del, I
> > can still move
> > the mouse, but I can't click anything.
>
> See above
>
> >(I known I shouldn't run X11 on a server.)
>
> You're right, the console of a server should not run X11 :(
> If you insist on running X11 on the console, maybe you should try to always
> keep an xterm open with console messages? (see /etc/syslog.conf)

X11 doesn't run on the console, it runs on ttyvb. And it doesn't run always. I 
only need it when I have to see graphics (I'm a command-line freak :-)).

> > > > FreeBSD has always managed the highest loads, even
> > > > on normal PC hardware. Is it possible to bring the server back
> > > > without rebooting? I would lose a lot of unsaved data if I had to
> > > > reboot. I'm running 4.8-STABLE.
> > >
> > > When a server responds to ping, but ssh times out etc it
> >
> > often relates
> >
> > > to hdd problems. Atleast in my experiences it has been so
> >
> > (dead disk).
> >
> > > And if it is hdd problems, and FreeBSD couldnt get the disk
> >
> > to wake up
> >
> > > again, you probably already have lost data.
> >
> > That could be the cause. One minute before the crash I could
> > still enter shell
> > builtin commands, but external commands did just nothing.
> >
> > Is it possible that the process table is full (I had more
> > than 450 processes
> > last time I ran top) or I ran out of memory (512M RAM + 1024M swap)?
>
> Well. Lets say that all the users use the same application. And all the
> users got the same bug with the application, wich made it forkbomb and
> consume large amounts of memory. 450 user-procs on the runaway could make
> this happen, but its very unlikely. FreeBSD is good at locking down things
> like this. But then again, if you run out of swap you're busted.

I guess it's something with the processes. I'm pretty sure the kernel was 
still alive.
The maximum number of processes is (maxusers * 20) + 18, right?