Top Nav

Performance Monitoring

Here are some handy commands that I used recently to debug a server performance issue:

Also “sar -A” give more useful info.

For sar to work, you need a cronjob like this:

The cronjob can go in a file at /etc/cron.d/sysstat on Redhat and similar systems.

Another useful command is “vmstat”:


Preferences vs. Command Line Options

Here’s my question answered by the author of DSpam – Jonathan Zdziarski:


Relay Control

In qmail, relaying is usually controlled by the tcpserver wrapper which uses a config file at either /etc/tcp.smtp or /home/vpopmail/etc/tcp.smtp.

The config file must be compiled into a binary format – “tcp.smtp.cdb” for actual use. Here’s the command line:

You don’t need to restart qmail after rebuilding the database.