Ensure that your system is prepared for vCenter Server upgrade by verifying compatibility and completing any necessary database, networking, or other preparation tasks. Verify Basic Compatibility Before Upgrading vCenter ServerVerify that all components meet basic compatibility requirements before upgrading vCenter Server. Preparing vCenter Server DatabasesvCenter Server requires a database to store and organize server data. You can either use the bundled PostgreSQL database that can be installed and configured at deployment time, or you can set up an external database. Verify Network Prerequisites Before UpgradingVerify that your network is set up correctly and meets connectivity prerequisites for upgrading vCenter Server. Verify Load Balancer Before Upgrading vCenter ServerIf you are using a load balancer for high availability for vCenter Single Sign-On, you must verify that it is supported and configured correctly before upgrading to vCenter Server 6.0. Prepare ESXi Hosts for vCenter Server UpgradeBefore upgrading to vCenter Server 6.0, you must prepare your ESXi hosts. Verify Preparations Are Complete for Upgrading vCenter ServerVerify that all components of your environment are ready to upgrade vCenter Server. Required Information for Upgrading vCenter Server for WindowsThe vCenter Server upgrade wizard prompts you for the upgrade information. It is a best practice to keep a record of the values that you entered in case you must reinstall the product. Required Information for Upgrading the vCenter Server ApplianceThe vCenter Server Appliance upgrade wizard prompts you for the deployment information. It is a best practice to keep a record of the values that you entered in case you must reinstall the product.