David Alcock has a script to create SQL Agent alerts for common errors:
These alerts cover a range of errors from potential IO subsystem problems to failed logins, all of which are things a DBA needs to know about, and quickly too.
As well as error notifications you can set up alerts to cover performance conditions. The final statement in the script below sets up an alert that triggers when Page Life Expectancy drops below 1000. In all honesty I don’t set up these performance alerts that often but I wanted to show you the kind of thing that is possible and would be handy if you don’t have any third party monitoring.
He follows this up with a post on appropriate response:
But what do I mean by sensible? Typically I see a number of problems with alerting setups; either alerts are inadequate and don’t cover the necessary errors (or there are none at all) but I also see the notifications to alerts not being set up correctly meaning problems go backwards and forwards delaying any fixes.
The other problem I see is an over provision of alerts. This usually is because one or more other monitoring systems have been deployed and error notifications have been duplicated as a result. Imagine having an operational tool like System Centre, some SQL monitoring software and native alerting all pinging the same message to the one recipient mailbox. Now on top of that let’s say the alerts have not been configured correctly so information emails are being issued every second. It’s a scary thought but it is easy to see how a critical error might be missed in this scenario.
If you don’t have automatic alerts for high-severity errors, this is an easy way of gaining insight into the problems your server is experiencing.