6.5.1

USB 3.0 Device Requirements
Starting with vSphere 5.5 Patch 3, USB 3.0 devices are available for passthrough not only from a client
computer to a virtual machine, but also from an ESXi host to a virtual machine. USB 3.0 devices still have
the following virtual machine configuration requirements:
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The virtual machine that you connect the USB 3.0 device to must be configured with an xHCI
controller and have a Windows 8 or later, Windows Server 2012 and later, or a Linux guest operating
system with a 2.6.35 or later kernel.
Avoiding Data Loss
Before you connect a device to a virtual machine, make sure the device is not in use on the client
computer.
If the vSphere Web Client disconnects from the vCenter Server or host, or if you restart or shut down the
client computer, the device connection breaks. It is best to have a dedicated client computer for USB
device use or to reserve USB devices connected to a client computer for short-term use, such as
updating software or adding patches to virtual machines. To maintain USB device connections to a virtual
machine for an extended time, use USB passthrough from an ESXi host to the virtual machine.
Connecting USB Devices to a Client Computer
You can connect and chain any multiple low, full, and high- or super-speed USB hubs and devices to a
client computer. Careful planning and knowledge of hub behavior and limitations can help ensure that
your devices work optimally.
USB physical bus topology defines how USB devices connect to the client computer. Support for USB
device passthrough to a virtual machine is available if the physical bus topology of the device on the client
computer does not exceed tier seven. The first tier is the USB host controller and root hub. The last tier is
the target USB device. You can cascade up to five tiers of external or internal hubs between the root hub
and the target USB device. An internal USB hub attached to the root hub or built into a compound device
counts as one tier.
The quality of the physical cables, hubs, devices, and power conditions can affect USB device
performance. To ensure the best results, keep the client computer USB bus topology as simple as
possible for the target USB device, and use caution when you deploy new hubs and cables into the
topology. The following conditions can affect USB behavior:
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Connecting or chaining multiple external USB hubs increases device enumeration and response time,
which can make the power support to the connected USB devices uncertain.
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Chaining hubs together increases the chance of port and hub error, which can cause the device to
lose connection to a virtual machine.
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Certain hubs can cause USB device connections to be unreliable, so use care when you add a new
hub to an existing setup. Connecting certain USB devices directly to the client computer rather than to
a hub or extension cable might resolve their connection or performance issues. In some cases, you
must remove and reattach the device and hub to restore the device to a working state.
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