Downtime always brings significant costs to any environment, so implementing a high availability solution is always necessary. Traditionally, however, it brings complexity in terms of manageability and cost.

VMware vSphere High Availability (vSphere HA) makes it simpler, easier, and cheaper to provide high availability for your applications. You can configure it with a couple of simple steps through VMware vCenter Server. You can create a vSphere HA cluster with multiple ESXi Servers, which will enable you to protect VMs and the services running on them. In the event of a failure of one of the hosts in the cluster, impacted VMs would be automatically restarted on other ESXi hosts within that same VMware vSphere Cluster.

There are many details to consider when configuring your HA cluster:

• Determining the size of your vSphere HA cluster
• Determining the number of resources to keep in reserve
• Determining when to use vSphere Fault Tolerance (FT)
• Determining when to use Distributed Power Management (DPM)

In this chapter, you will learn what you need to know about these to make sure you are running a balanced environment and thus achieving good performance in your vSphere Cluster.