Only the host system or the virtual machine can have control of a particular USB device at any one time. Device control operates differently, depending on whether the host system is a Linux or a Windows computer.

When you connect a device to a virtual machine, it is disconnected from the host system or from the virtual machine that previously had control of the device. When you disconnect a device from a virtual machine, it is returned to the host system.

Under some circumstances, if a USB storage device is in use on the host system, for example, one or more files stored on the device are open on the host, an error appears in the virtual machine when you try to connect to the device. You must let the host system complete its operation or close any application connected to the device on the host system and connect to the device in the virtual machine again.

On Windows XP and Windows Server 2003 host systems, a message might appear that says the device can be removed safely when you connect a USB network or storage device to a virtual machine. This is normal behavior and you can dismiss the dialog box, but do not remove the device from the physical computer. If the network or storage device does not disconnect from the host system, use the appropriate system tray icon to disconnect it. On Windows XP and Windows Server 2003, the system tray icon is called Safely Remove Hardware.