Patent ID: 8176222

Claim:
A computer program product for handling early termination of an input/output (I/O) operation at a channel subsystem in an I/O processing system, 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: opening a first exchange and transmitting a Transport control block (TCCB) to a control unit in communication with the channel subsystem, the TCCB specifying an I/O operation to be performed; opening a second exchange and transmitting a purge path Information Unit (IU) to the control unit, wherein the purge path IU includes an error code, the error code indicating to the control unit an error condition comprising a clear subchannel command sent from an operating system to the channel subsystem in the I/O processing system, a halt subchannel command sent from the operating system to the channel subsystem, a storage exception occurring due to an error in fetching or storing data in a host storage of a host system or a combination thereof, the host system including the channel subsystem; receiving from the control unit a purge path response IU associated with the transmitted purge path IU; and responsive to receiving the purge path response IU, transmitting a link level acknowledgment (LACK) to the control unit to close the second exchange.