In a cold migration upgrade, you power off or suspend the virtual machines that you move to a new host. When you use cold migration to move virtual machines, more downtime is required for the virtual machines.

This scenario assumes that the hosts do not have vMotion capabilities.

Upgrades using cold migrations are useful for situations that require a multistep upgrade, such as upgrades from versions lower than ESX 4.x.

Verify that one or more machines meets ESXi 5.1 requirements.

Verify that empty host storage is sufficient to hold a portion of your production virtual machines. Ideally, the storage is large enough to hold all of the migrated virtual machines. A larger capacity for virtual machines on this extra storage means fewer operations are required before all your virtual machines are migrated.

If your environment has vCenter Guided Consolidation, uninstall it before upgrading.

Run the vCenter Host Agent Pre-Upgrade Checker. See Run the vCenter Host Agent Pre-Upgrade Checker.

Upgrade vCenter Server 4.0 to vCenter Server 5.1. See Upgrading to vCenter Server 5.1.

Install the version 5.1 vSphere Client or vSphere Web Client. See Upgrade the vSphere Client.

If your environment has vCenter Update Manager, upgrade it to the latest version.


Add the ESXi 5.1 host to vCenter Server 5.1.


Add the ESX 4.x/ESXi 4.x hosts to vCenter Server 5.1.


Power off or suspend the virtual machines on the ESX 4.x/ESXi 4.x hosts.


Move the virtual machines to the ESXi 5.1 host.

For all hosts and virtual machines in the migration upgrade, take the following actions.

Upgrade your virtual machines. See Upgrading Virtual Machines.

Upgrade your product licenses:


Get your new license keys by email, or by using the license portal.


Apply the new license keys to your assets using the vSphere Client (or vCenter Server if you have it).