Not supported for direct upgrade

You must upgrade version 3.x ESX and ESXi hosts to ESX or ESXi v 4.x before you can upgrade them to 5.1

See the vSphere 4.x upgrade documentation

Alternatively, you might find it simpler and more cost effective to do a fresh installation of ESXi 5.1

Not supported.

The VMFS partition cannot be preserved. Upgrading or migration is possible only if there is at most one VMFS partition on the disk that is being upgraded and the VMFS partition must start after sector 1843200. Perform a fresh installation. To keep virtual machines, migrate them to a different system.

Supported. See Upgrade or Migrate Hosts Interactively.

The installer wizard offers the choice to upgrade or perform a fresh installation. If you upgrade, ESX partitions and configuration files are converted to be compatible with ESXi.

Supported. See Installing, Upgrading, or Migrating Hosts Using a Script.

In the upgrade script, specify the particular disk to upgrade on the system. If the system cannot be upgraded correctly because the partition table is incompatible, the installer displays a warning and does not proceed. In this case, perform a fresh installation. Upgrading or migration is possible only if there is at most one VMFS partition on the disk that is being upgraded and the VMFS partition must start after sector 1843200.

Partially supported.

You can upgrade the host as you would a normal ESX 4.x host, but no provisions will be made to optimize the partitions on the disk. To optimize the partition scheme on the host, perfrom a resh installation.

Not supported.

The most likely reasons for a missing Service Console are that the SC is corrupted or that the VMFS volume is not available, which can occur if the VMFS was installed on a SAN and the LUN is not accessible. In this case, on the disk selection screen of the installer wizrd, if you select a disk that has an existing ESX 4.x installation, the wizard prompts you to perform a clean installation.

Supported with ESXi Image Builder CLI.

If a 4.x host contains customizations, such as 3rd party VIBS or drivers, upgrading with the standard VMware installer ISO will result in the loss of those customizations and possibly an unstable system. See Upgrading Hosts that Have Third-Party Custom VIBs. You can use ESXi Image Builder CLI to create a customized ESXi installer ISO file that includes the VIBs or drivers. See the information on Image Builder in teh vSphere Installation and Setup documentation.

Supported.

When you upgrade an ESXi 5.x host that has custom VIBs to version 5.1, the custom VIBs are migrated. See Upgrading Hosts That Have Third-Party Custom VIBs.

Methods supported for direct upgrade to ESXi 5.1 are:

• vSphere Update Manager
• Interactive upgrade from CD, DVD or USB drive
• Scripted upgrade
• Auto Deploy. If the ESXi 5.0 host was deployed using Auto Deploy, you can use Auto Deploy to reprovision the host with an ESXi 5.1 image
• esxcli