The alerting framework in vRealize Operations is a very powerful feature of the solution. The ability of Symptoms, Recommendations, and Actions to come together to create meaningful and actionable alerts is something that was missing from previous versions.
As with Symptoms, Recommendations, and Actions, there are a lot of preconfigured Alert Definitions in Content, which are provided by the Solutions you install and configure.
If you navigate to Content | Alert Definitions you can see a list of all the Alert Definitions available.
Now, let's look at how Alert Definitions are constructed. The best way of doing this is to look at one of the more interesting out-of-the-box alerts: