Alarms in vSphere

In vSphere, alarms are notifications that occur in response to certain events or conditions that occur with an object in vCenter Server. It is possible to create alarms for vCenter Server objects such as VMs, ESXi hosts, networks, and datastores. Based on the object, these alarms can monitor resource consumption or the state of the object and alert you when certain conditions have been met, such as high resource usage or low disk space. Alarms are very useful because they allow you to be more proactive in the administration of your vSphere environment.

Each alarm type has three types of actions in common:

  • Send a notification email – informs you of the condition by email.
  • Send a notification trap – informs you of the condition by Simple Network Management Protocol (SNMP) trap.
  • Run a command – runs a script in order to correct the problem the object is experiencing.

vCenter Server has a number of built-in alarms. They can be used for generic purposes, such as informing you when a host’s power status changes, a datastore runs low on disk space, a VMs CPU usage is high, etc. You can also create your own alarms, if the default alarms are too generic for your purposes.

Alarms can’t be created by connecting directly to an ESXi host; vCenter Server is required for the alarm functionality.
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