vSphere is a sophisticated product with multiple components to upgrade. For a successful vSphere upgrade, you must understand the sequence of tasks required.
Upgrading vSphere includes the following tasks:
Read the vSphere release notes.
Verify that your system meets vSphere hardware and software requirements. See Upgrade Requirements.
Verify that you have backed up your configuration.
If your vSphere system includes VMware solutions or plug-ins, verify that they are compatible with the vCenter Server or vCenter Server Appliance version to which you are upgrading. See VMware Product Interoperability Matrix at http://www.vmware.com/resources/compatibility/sim/interop_matrix.php
Upgrade vCenter Server.
You can connect vCenter Server instances with external Platform Services Controller instances in an Enhanced Linked Mode configuration.Important:
Although you can select to join a vCenter Single Sign-On domain, you should consider vCenter Server with an embedded Platform Services Controller as a standalone installation and do not use it for replication of infrastructure data.
Concurrent upgrades are not supported and upgrade order matters. If you have multiple vCenter Server instances or services that are not installed on the same physical server or virtual machine (VM) as the vCenter Server instance, see Migration of Distributed vCenter Server for Windows Services During Upgrade to vCenter Server 6.0 and Mixed-Version Transitional Environments During vCenter Server Upgrades
Upgrade vCenter Server on a Windows VM or physical server or upgrade the vCenter Server Appliance. For the vCenter Server for Windows upgrade workflow, see About the vCenter Server 6.0 for Windows Upgrade Process. For the vCenter Server Appliance workflow, see About the vCenter Server Appliance Upgrade Process.
Prepare your environment for the upgrade. See Before Upgrading vCenter Server
Create a worksheet with the information that you need for the upgrade. See Required Information for Upgrading vCenter Server for Windows or Required Information for Upgrading the vCenter Server Appliance.
You can upgrade vCenter Server 5.0 to an embedded or external Platform Services Controller deployment. For vCenter Server 5.1 or 5.5 upgrades, your deployment outcome after upgrade depends upon your initial deployment. For more information on deployment details and how they affect upgrades, see About the vCenter Server 6.0 for Windows Upgrade Process,Upgrading the vCenter Server Appliance, Patching the vCenter Server Appliance and Platform Services Controller Appliance, and vCenter Server Example Upgrade Paths.
After upgrading vCenter Server, complete the post-upgrade tasks. Depending on your configuration details before upgrade, you might need to complete some reconfiguration tasks. See After Upgrading vCenter Server.
If you are using vSphere Update Manager, upgrade it. See Upgrading Update Manager.
Upgrade your ESXi hosts.
Determine the ESXi upgrade option to use. See Upgrade Options for ESXi 6.0.
Determine where you want to locate and boot the ESXi installer. See Media Options for Booting the ESXi Installer. If you are PXE-booting the installer, verify that your network PXE infrastructure is properly set up. See PXE Booting the ESXi Installer.
After upgrading ESXi hosts, you must reconnect the hosts to the vCenter Server and reapply the licenses. See After You Upgrade ESXi Hosts.
Consider setting up a syslog server for remote logging, to ensure sufficient disk storage for log files. Setting up logging on a remote host is especially important for hosts with limited local storage. See Required Free Space for System Logging and Configure Syslog on ESXi Hosts.
Upgrade your VMs and virtual appliances, manually or by using vSphere Update Manager, to perform an orchestrated upgrade. See Upgrading Virtual Machines and VMware Tools.