This property is not read-only, but the client cannot control its value. Persistent device keys are always assigned and managed by the server, which guarantees that all devices will have non-negative key values.

When adding new devices, it may be necessary for a client to assign keys temporarily in order to associate controllers with devices in configuring a virtual machine. However, the server does not allow a client to reassign a device key, and the server may assign a different value from the one passed during configuration. Clients should ensure that existing device keys are not reused as temporary key values for the new device to be added (for example, by using unique negative integers as temporary keys).

When editing or deleting a device, clients must use the server-provided key to refer to an existing device. @since VI API 2.5

Normally, two devices on the same controller may not be assigned the same unit number. If multiple devices could exist on a controller, then unit number has to be specified to configure respective devices. @since VI API 2.5

The virtual video device can use hardware acceleration and software rendering. By default, VMware products determine whether or not to use hardware acceleration based on the availability of physical graphics devices. Certain workloads can benefit from explicitly specifying if hardware acceleration is required. For example, 3D intensive workloads may indicate to run on systems with graphics hardware.

There are three settings.

(automatic) - The virtual device chooses how to render 3D graphics (default). (software) - The virtual device will use software rendering and will not attempt to use hardware acceleration. (hardware) - The virtual device will use hardware acceleration and will not activate without it. @since vSphere API 5.1