Upgrading is a multistage process in which procedures must be performed in a particular order. Follow the process outlined in this high-level overview to ensure a smooth upgrade with a minimum of system downtime.


Make sure that you understand the entire upgrade process before you attempt to upgrade. If you do not follow the safeguards, you might lose data and lose access to your servers. Without planning, you might incur more downtime than is necessary.

You must complete the upgrade process in a specific order because you can lose data and server access. Order is also important within each upgrade stage.

You can perform the upgrade process for each component in only one direction. For example, after you upgrade to vCenter Server 5.x, you cannot revert to vCenter Server 4.x. With backups and planning, you can restore your original software records.

You must complete one procedure before you move to the next procedure. Follow the directions within each procedure regarding the required sequence of minor substeps.

Because certain commands can simultaneously upgrade more than one stage, VMware recommends that you understand the irreversible changes at each stage before you upgrade your production environments.

To ensure that your datacenter upgrade goes smoothly, you can use vCenter Update Manager to manage the process for you.

vSphere upgrades proceed in the following sequence of tasks.


If your vSphere system includes VMware solutions or plug-ins, make sure they are compatible with the vCenter Server version that you are upgrading to. See the VMware Product Interoperability Matrix at http://www.vmware.com/resources/compatibility/sim/interop_matrix.php.


If you are upgrading vSphere components that are part of a VMware View environment, see Upgrading vSphere Components Separately in a Horizon View Environment.


Make sure your system meets vSphere hardware and software requirements.

See System Requirements.


If your vSphere deployment includes vCenter Server, upgrade vCenter Server.

See Upgrading to vCenter Server 5.1.


If you use VMware Update Manager, upgrade VMware Update Manager.

See Upgrading Update Manager.


Upgrade your ESXi hosts.

See Upgrading and Migrating Your Hosts. vSphere 5.1 provides several ways to upgrade hosts:

Use vSphere Update Manager to perform an orchestrated upgrade of your ESXi hosts. See Using vSphere Update Manager to Perform Orchestrated Host Upgrades.

Upgrade a single host at a time, interactively, from an ESXi ISO installer image stored on a CD, DVD, or USB flash drive. See Upgrade or Migrate Hosts Interactively.

Use a script to perform an unattended upgrade for multiple hosts. See Installing, Upgrading, or Migrating Hosts Using a Script

If a host was deployed using vSphere Auto Deploy, you can use Auto Deploy to upgrade the host by reprovisioning it. See Using vSphere Auto Deploy to Reprovision Hosts.

Upgrade or patch ESXi 5.0 hosts by using esxcli commands. See Upgrading Hosts by Using esxcli Commands.


Reapply your host license.

See Reapplying Licenses After Upgrading to ESXi 5.1.


Upgrade virtual machines and virtual appliances, manually or by using VMware Update Manager to perform an orchestrated upgrade.

See Upgrading Virtual Machines.