You can install or upgrade vCenter Single Sign-On in a basic, high availability, or multisite deployment.

To understand the Single Sign-On basic, high availability, and multisite deployment options, see vCenter Single Sign-On Deployment Modes.

Alternatively, if you are upgrading a version 4.x or 5.0.x vCenter Server installation, you can install vCenter Single Sign-On, upgrade vCenter Inventory Service, and upgrade vCenter Server together on a single host machine using the vCenter Server Simple Install option. This option is appropriate for small deployments. If you are upgrading a version 5.1.x vCenter Server installation, you must upgrade the vCenter Single Sign-On, vCenter Inventory Service, and vCenter Server components separately. See Using Simple Install to Upgrade vCenter Server.