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 ESX/ESXi host on which you create the virtual machine. Virtual hardware features include BIOS, number of 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 always corresponds to the host on which the virtual machine is created, or an earlier version.

Selecting an earlier hardware version is useful when you want to maintain compatibility with older hosts. 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 3.x or earlier host to an ESX/ESXi 4.x host.

You create a new virtual machine on an ESX 4.x host using an existing virtual disk that was created on an ESX/ESXi 3.x or earlier host.

You add a virtual disk created on an ESX/ESXi 3.x or earlier host to a virtual machine created on an ESX/ESXi 4.x host.

Virtual machines with hardware versions earlier than version 4 can run on ESX/ESXi 4.x hosts, but have reduced performance and capabilities. In particular, you cannot add or remove virtual devices on virtual machines with hardware versions earlier than version 4 when they run on an ESX/ESXi 4.x host. To make full use of these virtual machines, upgrade the virtual hardware as described in the Upgrade Guide.

Virtual Machine Hardware Versions lists virtual machine hardware versions; the ESX/ESXi versions on which they can be created, edited, and run; the vCenter Server versions on which they are fully supported; and a brief description of the hardware version’s capabilities.

Virtual Machine Hardware Versions

Version 7

Version 4

Version 3

Compatible with vCenter Server Version

ESX/ESXi 4.x

create, edit, run

create, edit, run

run

vCenter Server 4.x

ESX Server 3.x

create, edit, run

run

VirtualCenter Server 2.x and higher

ESX Server 2.x

create, edit, run

VirtualCenter Server 1.x and higher

Note

Virtual machine hardware version 4 might be listed as VM3 in documentation for earlier versions of ESX and ESXi. Virtual machine hardware version 3 might be listed as VM2 in documentation for earlier versions of ESX.