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Browse Prior Art Database

Physically Exchanging USB Devices with Minimal Operating System Impact

IP.com Disclosure Number: IPCOM000126510D
Original Publication Date: 2005-Jul-22
Included in the Prior Art Database: 2005-Jul-22
Document File: 1 page(s) / 22K

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This invention uses a number of conjoined methodologies to resolve this issue. The first methodology is the complete duplication of the device to be switched. The second methodology is the timing of the switch over event to coincide with a lull in USB traffic. The third methodology is the timing of the disconnect and reconnect events so as to minimally impact operating system awareness of the event. And the final methodology is a collection of implementations for reducing and/or eliminating operating system awareness.

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Physically Exchanging USB Devices with Minimal Operating System Impact

     On the next generation Blade Center, there will be occasions where the Management Module II will want to switch between a switched USB device path and a concurrent USB device path. The problem with this is that an operating system communicating with the USB device will not automatically switch over to the new USB device without loss of data. What is needed is a method to preserve data integrity as well as switch between the concurrent USB device and the switched USB device.

     The first point is that in order to make the operating system think that the same device is being disconnected and reconnected in a different port (or other as outlined below) we need to completely duplicate the connected device. The vendor id, product id, serial number and descriptor tables will match. The functionality of each interface on the USB device will also match. The only detectable difference would be the performance of the device (which is why we are exchanging the devices in the first place).

     The second point is that we will detect and monitor the USB traffic. At such a point in time that the USB traffic is at a minimum (or absent), the Management Module II will be able to move to the next step which is the disconnect event.

     The third point is that we will be disconnecting the old device prior to connecting the new device. The time between the disconnect reconnect will be such as to make the operating system an...