You can use the default vSAN alarms to monitor the cluster, hosts, and existing vSAN licenses.
The default alarms are automatically triggered when the events corresponding to the alarms are activated or if one or all the conditions specified in the alarms are met. You cannot edit the conditions or delete the default alarms. To configure alarms that are specific to your requirements, create custom alarms for vSAN. See Creating a vCenter Server Alarm for a vSAN Event.
For information about monitoring alarms, events, and editing existing alarm settings, see the vSphere Monitoring and Performance documentation.