Sometimes a server’s regular memory usage is fine. But there are those times when the server will run out of memory (OOM). And when that happens you may lose trace of what caused the server to run out of memory. Today, we will show you how to log possible memorry errors and see what can cause a problem for your VPS or Dedicated Server.

You can set up a script that will regularly log your server’s memory usage. And if there is a problem you can check the logs to see what was running. This additional log can be used in combination with the defaul tserver logs.

Type in the following, to create the needed file:

cat << EOF > /root/memmon.sh

When the file is ready, use your favorite text editor – vi, nano – to enter the following content

#!/bin/bash
date;
uptime
free -m
vmstat 1 5
ps auxf –width=200
if which iptables 2>&1 > /dev/null; then
iptables -L | diff iptables_default – | awk ‘{print “IPTABLES: ” $0}’
iptables -L > iptables_default
else
echo “IPTABLES MISSING”
fi
dmesg | diff -u dmesg_default – | grep ‘^+’ | awk ‘{print “DMESG:” $0}’
dmesg > dmesg_default
EOF

Now, make this file executable with the following command:

chmod +x /root/memmon.sh

It’s time to set up a cron job, which will execute this file every few minutes to check for the memory usage.

echo ‘0-59/10 * * * * root /root/memmon.sh >> /root/memmon.txt’ > /etc/cron.d/memmon

Then, restart the cron service:

/etc/init.d/cron* restart

The last thing to do is to create a logrotate entry for the new script, to avoid the file getting too large and taking too much disk space:

echo ‘/root/memmon.txt {}’ > /etc/logrotate.d/memmon

Tags: dedicated servers, OOM, VPS

This entry was posted on Monday, March 15th, 2010 at 10:17 am and is filed under Dedicated Hosting Services. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.