From: Daniel Denes (dd@speedlink.de)
Date: Tue Sep 17 2002 - 07:09:52 EDT
Hi List,
i've come across this thing yesterday on one of the production machines.
It has been reported to happen roughly once every month. As there is no
backup machine for this one, i didnt have a lot of time to examine the
problem but here is what i saw; maybe someone knows it.
The Machine is a E450 with 2 CPU's and 1.5GB RAM, configured with almost
5GB swap attached to a netApp filer i have no details about so far.
(attached = mounting stuff via NFS) The machine is running Solaris 8 and
is said to have a decent patch level.It is running several
configurations of apache 1.3.26, with the focus on mass virtual hosting
(using mod_vhost_alias). Furtheron it is running some version of exim
along with the qmail pop-daemon, and ncftp as well as mySQL. This is how
a typical top output looks like:
load averages: 3.50, 3.17, 2.61
13:00:16
264 processes: 261 sleeping, 1 running, 2 on cpu
CPU states: 20.3% idle, 39.2% user, 39.1% kernel, 1.4% iowait, 0.0%
swap
Memory: 1536M real, 750M free, 350M swap in use, 4733M swap free
Now, once every 4 weeks or so, the load goes up dramatically to 15 or
so, while the CPU usage state goes to about 75-80% usage in kernel mode.
There is no single process in the list that seems responsible; they all
hang around 1% CPU. I've tried killing single proc's, as well as
shutting down whole services, with an eye on the load; only when
shutting down the virtual-hosting-apache, the kernel load went down to
40-50% (which seems quite a lot, as there should be practically no load
on the machine when that apache is stopped).
I am new to the setup but the more experienced people here report that
several experts have had a look at that machine, to no avail.
Any ideas? How to proceed analyzing next time it happens? Can i
determine the process that slows the machine down somehow, or is it a
kernel problem?
Regards,
Daniel
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