You can upgrade the vCenter Server Appliance from version 5.5 or 6.0 to version 6.5. You can upgrade the Platform Services Controller appliance from version 6.0 to version 6.5.
When you run the GUI or CLI upgrade, the process includes:
Deploying a new appliance of version 6.5 with temporary network configuration
If you are upgrading a vCenter Server Appliance, you must select a deployment size for the new appliance that is suitable for your vSphere environment size. You must also select a storage size for the new appliance that is suitable for the vCenter Server Appliance database. If the source vCenter Server Appliance uses an external database, see Determine the Oracle Database Size and the Storage Size for the New Appliance.
Exporting the services and configuration data from the source appliance of version 5.5.x or 6.0.x. that you want to upgrade
You must select the data types that you want to transfer to the new appliance.
If you are upgrading a vCenter Server Appliance that uses an external Update Manager instance, you must ensure that the Migration Assistant is running on the Update Manager machine, which facilitates the export of the Update Manager configuration and database.
Transferring the exported data to the newly deployed appliance
Non-ephemeral distributed virtual port groups are not migrated. After the upgrade, you can manually connect the new appliance to a non-ephemeral distributed virtual port group.
If the source vCenter Server Appliance uses an external database, the database is migrated to the embedded PostgreSQL database of the new appliance.
If you are upgrading a vCenter Server Appliance that uses a Update Manager instance, the Update Manager instance is migrated to the embedded VMware vSphere Update Manager Extension of the new upgraded appliance.
Powering off the source appliance. The new upgraded appliance assumes the network configuration of the source appliance.
If your current appliance version is earlier than 5.5, you must upgrade to 5.5 or 6.0 before upgrading to version 6.5.
For the new appliance requirements, see System Requirements for the New vCenter Server Appliance and Platform Services Controller Appliance.
For the appliance upgrade preparation, see Preparing to Upgrade the vCenter Server Appliance and Platform Services Controller Appliance.
For the appliance upgrade procedures, see Upgrading the vCenter Server Appliance and Platform Services Controller Appliance.
For the appliance post-upgrade procedures, see After Upgrading or Migrating vCenter Server.