Q. Do I have to create a cluster in VMware vSphere to perform vMotion?

A. No. Clusters exist in vSphere, but they're only there for high availability and automated distribution of resources. You can actually perform a migration of virtual machines (VMs) that aren't part of any cluster, as you can see here with vMotion.

The only requirement is that the VMware hosts are running compatible processors and have access to the storage containing the VM, since you can't perform storage vMotion and normal vMotion at the same time.

Think of vMotion as a means to migrate active state without downtime. Think of clusters as features than can utilize vMotion to achieve their goals, primarily to move VMs between hosts for the purpose of balancing resources.

Remember that with vSphere, there are two uses for a cluster. (Both can be enabled for a single cluster.):

As you can see, vMotion is really only used in the DRS scenario, not in a host failure situation.

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