Patent ID: 7908403

Claim:
A computer program product for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: receiving a command message at the control unit from a first operating system of the plurality of operating systems via the one or more channels, wherein the command message includes an I/O operation command for a device in communication with the control unit; receiving a device busy indicator from the device, wherein the device busy indicator notifies the control unit that the device is reserved by a second operating system of the plurality of operating systems; queuing the command message on a device busy queue in response to the device busy indicator; initiating a device busy timer in response to queuing the command message on the device busy queue; monitoring the device for a device end indicator, wherein the device end indicator notifies the control unit that the device is ready to receive a new I/O operation command; servicing the device busy queue to perform the I/O operation command in response to the device end indicator; reading a value of the device busy timer in response to servicing the device busy queue to perform the I/O operation command, the reading performed by the control unit; and outputting the value of the device busy timer in a transport response information unit message to the first operating system via the one or more channels.