Processing communication data in a ships passing condition
First Claim
1. A computer program product for processing communications between a control unit and a channel subsystem in an input/output (I/O) processing system, comprising a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
- sending a message in a command mode from the control unit to the channel subsystem of a host computer system, the control unit configured to control an I/O device and receive information from the host computer system and the control unit via a channel path, the command mode using a first protocol that supports Channel Command Word (CCW) channel programs configured to support at least one CCW that specifies a command for performing an I/O operation;
receiving, by the control unit, a command in a transport mode from the channel subsystem at the control unit, the transport mode using a second protocol that supports Transport Control Word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to hold a plurality of commands for performing an I/O operation;
determining, by the control unit, whether the command is responsive to the message;
determining, by the control unit, that a ships passing condition has occurred between the channel subsystem and the control unit based on the command being not responsive to the message and the command being sent on the same logical path as the message; and
based on determining that the ships passing condition has occurred, determining by the control unit whether to perform one of i) executing the command and ii) terminating the command.
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Accused Products
Abstract
Articles of manufacture, apparatuses, and methods for processing communications between a control unit and a channel subsystem in an input/output processing system are disclosed. Embodiments of the invention include an article of manufacture including at least one computer usable medium having computer readable program code logic to processing communications between a control unit and a channel subsystem in an input/output processing system. The computer readable program code logic performs a method including: sending a message in a first mode from the control unit to the channel subsystem; receiving a command in a second mode from the channel subsystem at the control unit; determining whether the command is responsive to the message; and responsive to the command being not responsive to the message, determining whether to perform one of i) executing the command and ii) terminating the command.
194 Citations
20 Claims
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1. A computer program product for processing communications between a control unit and a channel subsystem in an input/output (I/O) processing system, comprising a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
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sending a message in a command mode from the control unit to the channel subsystem of a host computer system, the control unit configured to control an I/O device and receive information from the host computer system and the control unit via a channel path, the command mode using a first protocol that supports Channel Command Word (CCW) channel programs configured to support at least one CCW that specifies a command for performing an I/O operation; receiving, by the control unit, a command in a transport mode from the channel subsystem at the control unit, the transport mode using a second protocol that supports Transport Control Word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to hold a plurality of commands for performing an I/O operation; determining, by the control unit, whether the command is responsive to the message; determining, by the control unit, that a ships passing condition has occurred between the channel subsystem and the control unit based on the command being not responsive to the message and the command being sent on the same logical path as the message; and based on determining that the ships passing condition has occurred, determining by the control unit whether to perform one of i) executing the command and ii) terminating the command. - View Dependent Claims (2, 3, 4, 5, 6, 15, 16)
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7. An apparatus for processing communications in an input/output (I/O) processing system, comprising:
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a control unit capable of commanding and determining status of an I/O device, the control unit configured to communicate with a channel subsystem of a host computer system via a channel path, the control unit configured to perform; sending a message in a command mode to the channel subsystem, the command mode using a first protocol that supports Channel Command Word (CCW) channel programs configured to support at least one CCW that specifies a command for performing an I/O operation; receiving a command in a transport mode from the channel subsystem, the transport mode using a second protocol that supports Transport Control Word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to hold a plurality of commands for performing an I/O operation; determining whether the command is responsive to the message; determining that a ships passing condition has occurred between the channel subsystem and the control unit based on the command being not responsive to the message and the command being sent on the same logical path as the message; and based on determining that the ships passing condition has occurred, determining whether to perform one of i) executing the command and ii) terminating the command. - View Dependent Claims (8, 9, 10, 11, 17, 18)
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12. A method of processing communications between a control unit and a channel subsystem in an input/output (I/O) processing system, the method comprising:
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sending a message in a command mode from the control unit to the channel subsystem of a host computer system, the control unit configured to control an I/O device and receive information from the host computer system and the control unit via a channel path, the command mode using a first protocol that supports Channel Command Word (CCW) channel programs configured to support at least one CCW that specifies a command for performing an I/O operation; receiving, by the control unit, a command in a transport mode from the channel subsystem at the control unit, the transport mode using a second protocol that supports Transport Control Word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to hold a plurality of commands for performing an I/O operation; determining, by the control unit, whether the command is responsive to the message; determining, by the control unit, that a ships passing condition has occurred between the channel subsystem and the control unit based on the command being not responsive to the message and the command being sent on the same logical path as the message; and based on determining that the ships passing condition has occurred, determining by the control unit whether to perform one of i) executing the command and ii) terminating the command. - View Dependent Claims (13, 14, 19, 20)
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Specification