By keeping historical records, trends that will lead to problems can be nipped in the bud. Knowing that a disk is nearing capacity allows some quick file cleaning or additional storage to be added, before the system comes to a screeching halt. Managing Problems When They Occur After the detection of a problem, the persons responsible for the equipment or function in question should be notified, typically via e-mail or pager messages. The faster the notification, the greater the chance that the problem can be fixed without affecting customers or users. When implementing a notification scheme, remember that if the scheme can be disabled by the same problems that are being monitored, notification may not succeed.
Notification is fine, automatically correcting problems is even better.
A hung Web server process can be automatically restarted, a nearly full disk can have temporary files automatically cleaned off of it, or a flaky machine can be automatically rebooted. Automatically fixing as many problems as possible ensures minimum down time, and reduces the need for human intervention. Collecting and Using Historical Data Historical data allows the correlation of several sets of monitor readings, leading to a quicker diagnosis of problems. For example, if the CPU utilization of the Web server machine is very high, then failures to retrieve URLs during that period of time may be related to Web server overload rather than the failure of the Web server process itself. Historical data can also uncover trends that are useful in preventative maintenance.