The hardware version of a virtual machine reflects the virtual machine's supported virtual hardware features. These features correspond to the physical hardware available on the ESXi host on which you create the virtual machine. Virtual hardware features include BIOS and EFI, available virtual PCI slots, maximum number of CPUs, maximum memory configuration, and other characteristics typical to hardware.

When you create a virtual machine, you can accept the default hardware version, which corresponds to the host on which you create the virtual machine, or an earlier version. You can use an earlier hardware version in the following situations:

  • To standardize testing and deployment in your virtual environment.

  • If you do not need the capabilities of the newer version.

  • To maintain compatibility with older hosts.

Virtual machines with hardware versions earlier than version 8 can run on ESXi 5.0 hosts, but do not have all the capabilities available in hardware version 8. For example, you cannot use 32 virtual processors or 1011GB of memory in virtual machines with hardware versions earlier than version 8.

The vSphere Web Client or the vSphere Client allows you to upgrade virtual machines only to the latest hardware version. If virtual machines do not have to stay compatible with older ESX/ESXi hosts, you can upgrade them on ESXi 5.0 hosts. In this case, they are upgraded to version 8.

  • To maintain virtual machine compatibility with ESX/ESXi 3.5 hosts, upgrade the virtual machine on an ESX/ESXi 3.5 host, which results in a virtual machine upgrade to version 4.

  • To maintain virtual machine compatibility with ESX/ESXi 4.x hosts, upgrade the virtual machine on an ESX/ESXi 4.x host, which results in a virtual machine upgrade to version 7.

A virtual machine can have an earlier hardware version than that of the host on which it runs in the following cases:

  • You migrate a virtual machine created on an ESX/ESXi 4.x or earlier host to an ESXi 5.0 host.

  • You create a virtual machine on an ESXi 5.0 host by using an existing virtual disk that was created on an ESX/ESXi 4.x or earlier host.

  • You add a virtual disk created on an ESX/ESXi 4.x or earlier host to a virtual machine created on an ESXi 5.0 host.

You can create, edit, and run different virtual machine versions on a host if the host supports that version. Sometimes, virtual machine actions on a host are limited or the virtual machine has no access to the host.

Table 1. ESXi Hosts and Compatible Virtual Machine Hardware Versions

Version 8

Version 7

Version 4

Compatible with vCenter Server Version

ESXi 5.0

Create, edit, run

Create, edit, run

Edit, run

vCenter Server 5.0

ESX/ESXi 4.x

Not supported

Create, edit, run

Create, edit, run

vCenter Server 4.x

ESX Server 3.x

Not supported

Not supported

Create, edit, run

VirtualCenter Server 2.x and later

Version 3 virtual machines are not supported on ESXi 5.0 hosts. To make full use of these virtual machines, upgrade the virtual hardware.

Note:

Virtual machine hardware version 4 might be listed as VM3 in documentation for earlier versions of ESX/ESXi.