Orchestrated upgrades allow you to upgrade the objects in your vSphere inventory in a two-step process: host upgrades, followed by virtual machine upgrades. You can configure the process at the cluster level to automate more of the process, or you can configure it at the individual host or virtual machine level for granular control.
For example, you can define a host upgrade baseline to upgrade an ESXi 4.x host to ESXi 5.x, or you can define a virtual machine upgrade baseline to upgrade the VMware Tools and the virtual machine hardware to the latest version. Use wizard-based workflows to first schedule host upgrades for an entire cluster and then schedule a virtual machine upgrade for all the virtual machines.
You cannot use Update Manager to upgrade a host to ESXi 5.x if the host was previously upgraded from ESX 3.x to ESX 4.x. Such hosts do not have sufficient free space in the /boot partition to support the Update Manager upgrade process. This problem also affects some 4.x ESX hosts, even if they were not previously upgraded from ESX 3.x. Hosts must have more than 350MB of free space in the /boot partition to support the Update Manager upgrade process. If the host that you are upgrading does not have more than 350MB of free space in the /boot partition, use a scripted or interactive upgrade instead.
After you upgrade or migrate your host to ESXi 5.x, you cannot roll back to your version 4.x ESX or ESXi software. Back up your host before you perform an upgrade or migration, so that, if the upgrade or migration fails, you can restore your 4.x host.
The wizard workflows prevent erroneous upgrade sequences. For example, the wizard prevents you from upgrading virtual machine hardware before you upgrade hosts in a cluster.
You can use Distributed Resource Scheduler (DRS) to prevent virtual machine downtime during the upgrade process.
Update Manager monitors hosts and virtual machines for compliance against your defined upgrade baselines. Noncompliance appears in detailed reports and in the dashboard view. Update Manager supports mass remediation.
The following vSphere components are upgraded by Update Manager.
ESX and ESXi kernel (vmkernel)
Virtual machine hardware
For components that are not listed here, you can perform the upgrade by using another upgrade method, or, for third-party components, by using the appropriate third-party tools.
The following topics describe how to use Update Manager to conduct an orchestrated upgrade of your ESXi hosts.
To use Update Manager to conduct an orchestrated upgrade of virtual machines on your hosts, see the Installing and Administering VMware vSphere Update Manager documentation.