Hardware
Version
The hardware version of a virtual machine
indicates the lower-level virtual hardware features a virtual machine supports,
such as BIOS, number of virtual slots, maximum number of CPUs, maximum memory
configuration, and other hardware characteristics.
For a newly created virtual machine, the default
hardware version is the most recent version available on the host where the
virtual machine is created. To increase compatibility, you might want to create
a virtual machine with a hardware version older than the highest supported
version. You can do so by specifying the
VirtualMachineConfigSpec.version
property
during virtual machine creation. For existing virtual machines, call the
VirtualMachine.UpgradeVM_Task
method.
The hardware version of a virtual machine can be
lower than the highest version supported by the ESXi host it is running on
under the following conditions:
- You migrate a virtual machine to a newer version of ESXi after it was created on a host that was running an earlier version of ESXi.
- You create a virtual machine on a newer version of ESXi by using an existing virtual disk that was created on a host that was running an earlier version of ESXi.
- You add a virtual disk created on a host that was running an earlier version of ESXi to a virtual machine created on a newer version of ESXi.
Virtual machines with hardware versions lower
than 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 lower than 4 when they reside on an
ESX/ESXi 4.x host. To make full use of these virtual machines, upgrade the
virtual hardware.