4.11 Server Locks Up

[Mark Cullen]

Tom Grove wrote:
> Over the past few months I have noticed that our mail server is flat out 
> locking up.  I monitor it via Nagios and about once every two months I 
> get emails saying it is down and when I go over to the console the 
> server is totally unresponsive.  I've gone through logs every time and 
> find nothing at all wrong.
> This is a Dell PowerEdge 2850 with Dual Xeon cpu's and 2GB of memory.  
> Uname replies with:
> 
> FreeBSD colossus 4.11-RELEASE-p13 FreeBSD 4.11-RELEASE-p13 #0: Fri Oct 
> 14 13:34:01 EDT 2005     root at colossus:/usr/obj/usr/src/sys/COLOSSUS  i386
> 
> One, has anyone else had similar problems with boxes just becoming 
> unresponsive under high load?  Two, is there any reason this would occur?
> 
> -Tom Grove
> 
> 
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I have very recently (a couple of weeks a go) had my small home server 
start randomly deciding to lock up, not even under heavy load. It would 
just decide to freeze up for no reason. It would happen usually at least 
once a week, and it was fairly common for it to lock up during the O/S 
boot. It would never lock up in BIOS though.

After replacing every single piece of hardware in the machine, aside 
from the motherboard, nothing seemed to help. Upon further inspection of 
the motherboard, just before looking to buy a new one, I noticed bulging 
/ leaking capacitors around the CPU socket. It looked like *all* of the 
most important caps were knackered. I am suprised it managed to turn on 
and stay up (for a while) at all.

Just the other day I ordered some good brand name caps (Rubycon MCZ's) 
and replaced all but 3 of the original capacitors on the board. It's 
been up for 11 days with no signs of locking up. Before leaving it on 
again I tested it out, just by restarting a fair few times, to see if it 
continued to lock up during O/S boot. Not *once* did it lock up after 
the capacitor replacement jobby I did. It appears to have solved all my 
instability problems!

It may be a long shot, but it's perhaps worth perhaps checking the 
capacitors and making sure they're in good condition. Even a slight 
bulge is the sign of a failing capacitor, as far as I am aware. The tops 
should be *perfectly* flat, and nice and shiny :-) Of course, you may 
not be comfortable taking a soldering iron to your board. If you do 
discover bad caps and would like to have them replaced by someone with 
experience, take a look at www.badcaps.net. They offer a paid service 
for capacitor replacement. Not exactly certified by any motherboard 
manufacturers or anything, but appears to have a lot of experience.