Resolution - ClearCube R1200 Technical Document

A number of factors contribute to this problem. First and most significantly, firmware inside the C/Port rec-
ognizes but does not always accurately report the existence of a USB device attached to the Blade, even
though the C/Port is itself a USB device. So when the Blade reboots, it polls the USB ports and locates the
C/Port as a USB device, and configures it appropriately. If other USB devices such as a keyboard, mouse,
or mass storage device (assuming mass storage has been activated on the host Blade for the connected
C/Port) are connected to the C/Port at reboot, they are recognized as well. Notably, PS/2 input devices are
recognized as a part of the C/Port, and will properly wake up the Blade if they were plugged in at startup.
However, if users or administrators hot-swap cables on the C/Port, including using a Switching Backpack
to reassign either the Blade or the C/Port, incorrect USB power settings can cause the C/Port to become
inaccessible. If the USB Root Hubs are set to "save power" (see Figure 1), the system may recognize the
momentary disconnection of any USB device to mean that all USB devices have been disconnected,
including the C/Port itself. Thus, all control at the C/Port can be lost completely until the system is rebooted
locally.
The likeliest culprit among the USB Root Hubs is the third hub in the list shown in Figure 1. This list typi-
cally has either three or four hubs. The third hub must remain unchecked. This hub can become checked
without notice when one of the following situations occurs:
• A hyperthreaded drive image has been installed on a system with a non-hyperthreaded processor.
• Drive image defaults have been incorrectly set for the processor.
• Unknown USB or KVM hardware has been hot-swapped at the C/Port after WIndows has booted. Win-
dows will not recognize new KVM hardware until restart, and may not recognize new USB hardware
uness the device works with one of the default USB drivers in Windows.
ClearCube drive images are specially prepared to prevent these problems or to mitigate their effects. Drive
images are configuration-specific, and while many organizations have significant reasons to develop cus-
tom configurations and images, changing some settings may cause unpredictable results.

RESOLUTION

Follow the procedure on the first page of this Technical Bulletin to reset USB power-saving to "off" each
time this problem re-occurs until your drive image has been corrected.
Use the correct drive image for your Blade. Do one of the following:
• Use ClearCube-supplied drive images.
• Use the correct image.
• Do not apply a hyperthreaded image on a Blade that has a non-hyperthreaded processor (e.g., a Cel-
eron processor).
• If you develop your own drive images, ensure that you correctly specify hyperthreading in the images
you create. Work with your ClearCube systems engineer and with ClearCube technical support to
ensure that your custom configurations use valid, tested settings.
Configure your hardware and system correctly.
• Ensure that power saving for the third USB Root Hub is always turned OFF.
• Ensure that the correct drivers are loaded on your system, and test drivers for devices that cannot use
the default Windows drivers. ClearCube cannot test every driver written for every peripheral device
available for Windows systems.
• Be aware that your Blade may not reliably recognize a new and previously unknown USB device that
is hot-plugged into a C/Port after Windows completes booting. Should this occur, the most practical
resolution is to reboot the Blade locally. This issue is documented in Tech Bulletin SE0053CP, Hot-
Plugging the Digital Link after Booting Windows.
• Do not attach a USB device at the Blade to circumvent this behavior. PS/2 mice and keyboards will be
recognized if they were present at the last reboot, but other peripheral USB devices at the C/Port may
be disabled. This issue is described in Tech Bulletin SE0052CP, USB Devices on Blade Front Panel
Disables C/Port USB Storage.
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ClearCube Public Technical Document
Document Code: SE0062JS