Abstract: A computer program product, apparatus, and method for providing exception condition feedback at a control unit to a channel subsystem in an I/O processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a command message at the control unit from the channel subsystem, and detecting an exception condition in response to unsuccessful execution of at least one command in the command message. The method further includes identifying a termination reason code associated with the exception condition, writing the termination reason code to a response message, and sending the response message to the channel subsystem.

Abstract: A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method including: sending a message from the channel subsystem to the control unit in a first mode; receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and responsive to the message protocol being supported by the control unit, sending another message using the message protocol from the channel subsystem to the control unit to determine whether the control unit supports a second mode.

Abstract: A computer program product, apparatus and method for processing a variable length device command word (DCW) at a control unit configured for communication with an input/output (I/O) subsystem in an I/O processing system. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a DCW at the control unit from the I/O subsystem. The DCW specifies one or more I/O operations and includes a command, a control data count, and control data having a varying length specified by the control data count. The control data is extracted in response to the control data count. The command is then executed in response to the extracted control data to perform the specified one or more I/O operations.

Abstract: A computer program product, an apparatus, and a method for reducing reserved device access contention at a control unit in communication with a plurality of operating systems via one or more channels are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method that includes receiving a command message at the control unit from a first operating system, including an I/O operation command for a device. A device busy indicator is received, indicating that a second operating system has reserved the device. The command message is queued on a device busy queue in response to the device busy indicator. The control unit monitors for a device end indicator. The device busy queue is serviced to perform the I/O operation command in response to the device end indicator.

Abstract: A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method.

Abstract: A computer program product, an apparatus, and a method for processing communications between a target and an initiator an input/output processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes: sending a message between the initiator and the target, the message requesting suspension of input/output operations between the initiator and the target for a period of time, the period of time being defined by the message; and responsive to the message, suspending input/output operation messages for the period of time.

Abstract: An article of manufacture, apparatus, and a method for facilitating input/output (I/O) processing for an I/O operation at a host computer system configured for communication with a control unit. The method includes the host computer system obtaining a transport command word (TCW) for an I/O operation having both input and output data. The TCW specifies a location of the output data and a location for storing the input data. The host computer system forwards the I/O operation to the control unit for execution. The host computer system gathers the output data responsive to the location of the output data specified by the TCW, and then forwards the output data to the control unit for use in the execution of the I/O operation. The host computer system receives the input data from the control unit and stores the input data at the location specified by the TCW.

Abstract: A computer program product, apparatus, and method for inserting multiple CRCs in an output data stream from a channel subsystem to a control unit are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a message to transmit from the channel subsystem to the control unit. The method also includes determining a first CRC insertion position, and receiving a first CRC calculated over a first block of data in the message. The method additionally includes inserting the first calculated CRC at the first CRC insertion position, and determining a second CRC insertion position. The method further includes receiving a second CRC calculated over a second block of data in the message, and inserting the second calculated CRC at the second CRC insertion position.

Abstract: Provided are a method, system, and article of manufacture, wherein a control unit receives a request to establish a relationship over a fibre channel connection, wherein a first indicator associated with the request indicates that the relationship supports persistent information unit pacing across a plurality of command chains. The control unit sends a response indicating an acceptance of the relationship, wherein a second indicator associated with the response indicates that the control unit supports persistent information unit pacing across the plurality of command chains. An information unit pacing parameter value is retained across the plurality of command chains, in response to determining that the second indicator indicates that the control unit supports persistent information unit pacing across the plurality of command chains.

Abstract: Data transfer between input/output devices and memory is controlled. Data transfer begins under the control of one control block, and control of the data transfer is passed from the one control block to another control block, in response to transferring an amount of data specified in the one control block. The passing of control occurs independent of a memory boundary, providing flexibility in controlling the data transfer. Each control block includes fields that control and facilitate the data transfer.

Abstract: State information is communicated in a network to more efficiently utilize network resources. A first node forms a single extended query requesting state information from at least one logical image of a second node. The extended query is a single query requesting state information for multiple logical images of the first node. The requested state information includes the status of logical paths previously established between the multiple logical images of the first node and the at least one logical image of the second node. Upon sending the extended query to the second node, a single extended response can be formed at the second node having the requested state information.

Abstract: A data communication architecture including a plurality of devices having input/output (I/O) ports supporting communication at a first rate and a data processor having a number of I/O ports where each I/O port supports data communication at a second data rate. The second data rate is at least double the first data rate. A communication link coupled to one of the data processor I/O ports supports the second data rate. A bridge device is coupled to the communication link and to the I/O ports of the plurality of devices. The bridge device translates the communication link at the second data rate to a plurality of communication links at the first data rate, where the plurality of communication links at the first data rate are substantially independent of each other.

Abstract: The present invention provides fiber channel networks the ability to logically disconnect without closing an exchange pair wherein the control unit signals the channel that the channel can elect to keep the exchange open by sending the channel a status command. A preferred status command to permit the channel to keep the exchange open includes an End Connection=‘0’ with Channel End=‘1’ and device end=‘0’.

Abstract: A data communication architecture including a plurality of devices having input/output (I/O) ports supporting communication at a first rate and a data processor having a number of I/O ports where each I/O port supports data communication at a second data rate. The second data rate is at least double the first data rate. A communication link coupled to one of the data processor I/O ports supports the second data rate. A bridge device is coupled to the communication link and to the I/O ports of the plurality of devices. The bridge device translates the communication link at the second data rate to a plurality of communication links at the first data rate, where the plurality of communication links at the first data rate are substantially independent of each other.

Abstract: A data communication architecture including a plurality of devices having input/output (I/O) ports supporting communication at a first rate and a data processor having a number of I/O ports where each I/O port supports data communication at a second data rate. The second data rate is at least double the first data rate. A communication link coupled to one of the data processor I/O ports supports the second data rate. A bridge device is coupled to the communication link and to the I/O ports of the plurality of devices. The bridge device translates the communication link at the second data rate to a plurality of communication links at the first data rate, where the plurality of communication links at the first data rate are substantially independent of each other.

Abstract: State information is communicated in a network to more efficiently utilize network resources. A first node forms a single extended query requesting state information from at least one logical image of a second node. The extended query is a single query requesting state information for multiple logical images of the first node. The requested state information includes the status of logical paths previously established between the multiple logical images of the first node and the at least one logical image of the second node. Upon sending the extended query to the second node, a single extended response can be formed at the second node having the requested state information.

Abstract: A method, program product and apparatus for checkpointing for recovery of channels in a data processing system using a protocol which allows for multiplexing operations at the frame level and streaming of commands and data. For unsuccessful retries, the correct primary CCW address is reported back to software indicating the extent to which the channel completed modifying and accessing S/390 storage.

Abstract: The present invention provides a method for fibre channel control units to execute commands locally when a channel sends a repeat execute indicator in conjunction with certain other field settings, wherein the control unit will repeat and chain control words until certain predefined conditions occur.

Abstract: The present invention provides for a method of transferring information in a network computing system environment. The network environment includes a main storage coupled to a channel subsystem with a plurality of channels which is in processing communication with a control unit capable of coupling to a plurality of input/output devices. At first the packets of data are sent concurrently to and from the main storage. Next execution of certain channel functions are transferred to the control unit so that certain commands can be combined with the data packets in one sequence. Finally only one start data command and only one end command notification needs to be sent before and after a plurality of data packets is transferred respectively.

Abstract: The present invention provides fiber channel networks the ability to detect lost information units transmitted be nodes. Each information unit includes a new count field that identifies the unit as a sequential event. When the information unit is received, the count field is compared with the count field saved from the previous unit and an error is asserted if the count is not the expected value.