With vSphere vMotion, you can migrate powered on virtual machines from one physical server to another without service interruption. The result is a more efficient assignment of resources, and you can avoid using an out-of-hours downtime model of maintenance.

When you use vMotion, you do not have to wait until a downtime window to perform maintenance. vMotion enables you to move a virtual machine from one host to another without powering off the virtual machine. You can use vMotion to move virtual machines off a host so that you can perform host maintenance without virtual machine downtime. You can perform fundamental maintenance during business hours without service interruption.

In addition, vSphere Distributed Resource Scheduler (DRS) uses vMotion to balance the resource load in clusters of physical hosts, managing a cluster as a single compute resource.

Before you can migrate a virtual machine with vMotion, you must configure both the source host and destination host. You can also configure a cluster of hosts for vMotion.

Whether you configure vMotion in hosts independently or within a cluster, vMotion has a set of requirements covering licenses, storage, and networking. See Host Configuration Requirements for vMotion.

Setting up a host for vMotion includes verifying that vMotion is licensed on the hosts, and configuring networking for either vSphere standard switches or vSphere distributed switches. See Set Up a Host for vMotion.

DRS places virtual machines so that the load across a cluster is balanced, and cluster-wide resource allocation policies (for example, reservations, priorities, and limits) are enforced. As cluster conditions change (for example, load and available resources), DRS uses vMotion to migrate virtual machines to other hosts as necessary.

Setting up a cluster for vMotion includes setting up individual hosts, but also entails creating the cluster and adding managed hosts to the cluster. See Set Up a Cluster for vMotion.

You use the Enhanced vMotion Compatibility (EVC) feature to ensure vMotion compatibility between the hosts in the cluster. See About Enhanced vMotion Compatibility.