Preparing Your Toolbelt

You have a variety of tools at your fingertips to help work out the cause of a problem. Over time you will expand what is in your toolbelt, but to start with you must know how to use each of these:

• top, vmstat, iostat, systat, sar, mpstat help you see the current state of the system - what is running, what is using cpu, memory? Is the disk being heavily used? There is a great deal of information, and knowing how these tools work will help you pick out the bits you should focus on.

• tcpdump, ngrep If you suspect you have a network-related problem, tcpdump and ngrep can help you confirm it.