Upgrade a single/complex PSC installation

If you have a complex vSphere environment with more external PSCs, and perhaps with multi-site deployment, the upgrade process can be a little more critical.

To upgrade a vSphere environment, there is a general order that must be followed. For the basic vSphere components, perform the following:

1. External PSC: Upgrade each SSO or PSC, one by one. Applicable only in external PSC deployments.
2. vCenter Server: Upgrade each vCenter Server, one by one.
3. ESXi hosts: Upgrade each ESXi host, one by one.

For the PSC components, it's usually preferable to upgrade them during the maintenance windows, to avoid authentication issues. But, if all external PSCs are configured in a high availability configuration, with external load balancers, you can perform upgrades on PSCs one by one, without interruptions.

For more information about each transitional step, including diagrams, see the Upgrade or Migration Order and Mixed-Version Transitional Behavior for Multiple vCenter Server Instance Deployments section in the vSphere Upgrade Guide (https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.upgrade.doc/GUID-FDF1D082-36EB-41EB-9D97-A48D33A1D843.html).

For the vCenter Server appliance (for both vCenter and PSC), the update and upgrade process can be managed from the VAMI UI. The update is quite simple (for example, using an external URL), and the upgrade requires the VCSA 6.5 ISO.

The VCSA GUI upgrade is a two-stage process (like the installation). The first stage is a deployment wizard that deploys the OVA file of the new appliance on the target ESXi host or vCenter Server instance. After the virtual appliance deployment finishes, you are redirected to the second stage of the process, which sets up and transfers the services and configuration data from the old appliance to the newly deployed appliance.

For more information, see KB 2147686 (https://kb.vmware.com/s/article/2147686)—Best practices for upgrading to vCenter Server 6.5.