The Sysadmin's Toolbox: sar
As someone who's been working as a system administrator for a number of years, it's easy to take tools for granted that I've used for a long time and assume everyone has heard of them. Of course, new sysadmins get into the field every day, and even seasoned sysadmins don't all use the same tools. With that in mind, I decided to write a few columns where I highlight some common-but-easy-to-overlook tools that make life as a sysadmin (and really, any Linux user) easier. I start the series with a classic troubleshooting tool: sar.
There's an old saying: "When the cat's away the mice will play." The same is true for servers. It's as if servers wait until you aren't logged in (and usually in the middle of REM sleep) before they have problems. Logs can go a long way to help you isolate problems that happened in the past on a machine, but if the problem is due to high load, logs often don't tell the full story.