Hey hareshn,
I typically create two custome alarms for this:
1.) From your cluster or vCenter level in the alarms definitions view right click and create a new alarm
2.) In the General Tab name your alarm and under the monitor drop down select Hosts
3.) Under the hosts selection select Monitor for specific events occuring on this object, for example, vm power on radio button
4.) Make sure the alarm is enabled
5.) Under the Triggers tab in the events section near the end of the event colum click the drop down arrow, it usally invisiable or hiding till your mouse is over it, then select Lost Storage Path Redundacy, you don't need any advanced conitions
6.) Under the Actions tab setup a email notification and the actoins to take. I set mine up for: Once from green --> Yellow, Once for Yellow --> Red
Repeat this process for the second alarm however at step 5.) in the drop down select Datastore Path Redundacy
There is a bunch of others in the drop down list that you can pick from.