Troubleshooting

If your server goes down, and you get a message like:

Feb 16 03:00:12 server kernel: INFO: task httpd:16101 blocked for more than 120 seconds.

Verify memory usage:

sar -r

Verify CPU usage:

sar -u

For me the culprit was CPU reaching %idle reaching 99.18

Source

About this series

The typical UNIX® administrator has a key range of utilities, tricks, and systems he or she uses regularly to aid in the process of administration. There are key utilities, command line chains, and scripts that are used to simplify different processes. Some of these tools come with the operating system, but a majority of the tricks come through years of experience and a desire to ease the system administrator's life. The focus of this series is on getting the most from the available tools across a range of different UNIX environments, including methods of simplifying administration in a heterogeneous environment.