High Fibre Programming

I recently upgraded my Ubuntu install to the latest Karmic Koala, and to be honest I’ve not been totally impressed.   A range of little bugs that had been fixed before seem to have reappeared – just little things such as problems with icons in Gnome panel, nothing I couldn’t live with.

However, yesterday I got a message saying that there was less than 2GB left on my hard drive.   The last time I checked I had over 20GB free, so where did it all go?   After a bit of investigating I found two giant 10GB kernel log files /var/log/kern.log.

It seemed that the computer was constantly logging the same messages:

CPU0: Temperature above threshold, cpu clock throttled (total events = 208[ 8973.550089] CPU0: Temperature/speed normal

CPU0: Temperat cpu clock throttled (total events = 2080190)

I had a look on Google and it turns out that it is a bug with the new Karmic Koala update:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/453444

So far there’s no patch for it, so the best solution I came up with was just to turn off the logging.

Step 1:
Look in /etc/rsyslog.conf and it will either have the configuration for system logging, or in the case of my machine it points to include all files in /etc/rsyslog.d/   In my case there was only one file in here so it made things simpler.

Step 2:
Open the configuration file in an editor and find the line which specifies kernel logging and comment it, something like:

#kern.*                         -/var/log/kern.log

Step 3:
Now restart the system log daemon:   sudo restart rsyslog

It is the logging which hogs the processor so by turning it off the problem is at least not noticeable.

We decided it would be a good idea to be able to periodically log server load so we can identify potential problems So I wrote a little script that outputs the current server load along with a timestamp in CSV format which can easily be called via CRON and send the output to a log file which can then be imported into a spreadsheet.

getload.c

Just compile it and run it. The output should be something like:

"1251834476","0.21"

It turns out that Nagios logs server load anyway, but not quite as accurately as this.

I was looking for a way to get rsync to copy all the files in a particular directory and not recurse into the sub-directories.   Unfortunately I couldn’t find an appropriate parameter and a quick search on Google turned up nothing (apart from a lot of other people asking the same question!)

So as a last resort I decided to use my brain, and I came up with a simple solution that works.   It’s of the form:

rsync -avc --exclude "*/" ./source/* ./destination/


The above will copy all the files from the directory called “source” into the directory “destination” and will not recurse into any subdirectories of “source”.