In this article we will learn how to create and manage alarms in VMware vCenter server. We will cover the following topics:

  • What is a vCenter alarm?
  • How to configure alarms
  • Working with alarms
  • How to setup email alerts

What are vCenter Alarms?

VMware vCenter alarms are important parts of a proactive monitoring system that can automatically create alert notifications that occur in response to selected events, conditions, and states that happen with objects in the inventory.

VMware Training – Resources (Intense)

The vCenter Server system is configured with a set of predefined alarms that monitor clusters, hosts, datacenters, datastores, networks, and virtual machines. It is also configured with alarms that monitor vCenter Server licensing. Set correctly, these vCenter alarms can improve response time and help prevent downtime or degraded VM performance.

The image below shows a pre-configured alarm at the data center level:

When you set an alarm on a parent object, such as a vCenter Server, a datacenter or a cluster, all applicable child objects inherit the alarm. You can also set an alarm on a folder to propagate the same alarm to all objects contained in that folder. You cannot change or override an alarm that is set on a child object from its parent object though; you must change the alarm on the child object itself.

How to Configure Alarms

When working with VMware vCenter alarms, it is important to determine the scope of each alarm. You can create alarms at the data center level, the cluster level, the host level or even for a specific VM.

STEP 1 – Navigate to the level of the vSphere infrastructure where you want to create an alarm; in this example, we will create an alarm at ESXi host level.

STEP 2 – Select the ESXi host and go to the Alarms tab and from there, the Alarm Definitions view.

STEP 3 – Right-click and select New Alarm.

STEP 4 – Give the alarm a useful and descriptive name and select the correct alarm type.

STEP 5 – Now select the second tab “Triggers” and configure the options per requirement. To add a trigger, right-click in the client area and select “Add Trigger.”

STEP 6 – Now select the “Reporting” tab and configure the range and frequency. In the final tab “Actions” we need to specify the type of action that vCenter needs to take. In this example, we want it to send out an email notification alert. We need SNMP configured for the email notification to function properly, which will be covered later in this article.

Working with Alarms

We have looked at the default alarms created in the vCenter under “Definitions” and we also covered the process of create custom alarms.

In the event that an alarm is triggered during a host failure, the alarm would be featured in the “Triggered Alarms” tab. The example below highlights an ESXi host failure:

Let’s assume the ESXi in this example was brought offline for hardware maintenance and it can be safely ignored. We can acknowledge the alarm by right-clicking it and selecting “Acknowledge Alarm.”

VMware uses colors to denote alarm severity:

  • * Normal: green
  • * Warning: yellow
  • * Alert: red

How to Setup Email Alerts

The first thing we have to do is configure vCenter to send out email and SNMP alerts.

Navigate to Home > vCenter Servers Settings, select “Mail” from the left-hand side and enter the required details. Then select SMTP and enter your SMTP Server details:

If you need the Management Information Base (MIBs), these can found at %ProgramFiles%\VMware\Infrastructure\VirtualCenter Server\MIBS if the default installation path has been used.

MIBs describe Object Identifiers (OIDs ) for SNMP. This is useful for monitoring applications so they know what they’re looking at. MIBs also include definitions for the kind of data returned by a specific OID.


In this article, we learned that creating a new alarm in vCenter is easy by following simple steps. VMware has pre-configured and enabled alarms that we can already use. We also saw how to work and acknowledge alarms and locate MIB files.

It is crucial for vSphere administrators to understand how alarms work in order to properly monitor their virtual infrastructure and to be alerted of issues that need to be resolved.

I hope you enjoyed reading this topic on VCP5 preparation and thank you for reading!