Abstract: A method to adjust a multi-path device reservation by supplying a computing device and a storage controller interconnected with a communication link. The method further reserves a data storage device in communication with the storage controller, where that data storage device reservation is held by a first communication path group comprising a first plurality of communication paths configured in the communication link. If the method detects a failed communication path configured in the first communication path group, the method configures a second communication path group by removing the failed communication path from the first communication path group, wherein the second communication path group maintains the data storage device reservation.

Abstract: Method, system and computer program product embodiments for, in an input/output (I/O) link handling complex instruction chains, a messaging scheme incorporating a method of error recovery between an initiator processor and a receiver processor, are provided. An operation initiation message is been sent from the initiator processor to the receiver processor for the receiver processor to begin work on an operation. If determined to be necessary, a terminate operation message is sent from the initiator processor to the receiver processor. The initiator processor withholds sending additional messages for the operation until a terminate operation response message is received. Once the terminate operation message is received, outstanding messages in process are flushed from the receiver processor. The receiver processor withholds sending additional messages to the initiator processor as the outstanding messages are completed.

Abstract: A method for facilitating input/output (I/O) communication for a processing operation is provided. An interrogate command is obtained by an I/O communications adapter. The interrogate command queries for status information of the processing operation to be provided in an interrogate response. A fixed number of resources and a time allocated to the interrogate command is throttled by pre-allocating the fixed number of resources needed for the interrogate command, and maintaining a timestamp for a interrogate message. The interrogate message is forwarded from the I/O communications adapter to a control unit. If the interrogate response is not received by the I/O communications adapter within a limited timeout period as measured by the timestamp, or if the interrogate message is received while the fixed number of pre-allocated resources are in use, the I/O communications adapter returns a busy response indicating the control unit is busy to prevent overrunning the control unit.

Abstract: A method to adjust a multi-path device reservation by supplying a computing device and a storage controller interconnected with a communication link. The method further reserves a data storage device in communication with the storage controller, where that data storage device reservation is held by a first communication path group comprising a first plurality of communication paths configured in the communication link. If the method detects a failed communication path configured in the first communication path group, the method configures a second communication path group by removing the failed communication path from the first communication path group, wherein the second communication path group maintains the data storage device reservation.

Abstract: A method for facilitating input/output (I/O) communication for a processing operation is provided. An interrogate command is obtained by an I/O communications adapter. The interrogate command queries for status information of the processing operation to be provided in an interrogate response. A fixed number of resources and a time allocated to the interrogate command is throttled by pre-allocating the fixed number of resources needed for the interrogate command, and maintaining a timestamp for a interrogate message. The interrogate message is forwarded from the I/O communications adapter to a control unit. If the interrogate response is not received by the I/O communications adapter within a limited timeout period as measured by the timestamp, or if the interrogate message is received while the fixed number of pre-allocated resources are in use, the I/O communications adapter returns a busy response indicating the control unit is busy to prevent overrunning the control unit.

Abstract: Method, system and computer program product embodiments for, in an input/output (I/O) link handling complex instruction chains, a messaging scheme incorporating a method of error recovery between an initiator processor and a receiver processor, are provided. An operation initiation message is been sent from the initiator processor to the receiver processor for the receiver processor to begin work on an operation. If determined to be necessary, a terminate operation message is sent from the initiator processor to the receiver processor. The initiator processor withholds sending additional messages for the operation until a terminate operation response message is received. Once the terminate operation message is received, outstanding messages in process are flushed from the receiver processor. The receiver processor withholds sending additional messages to the initiator processor as the outstanding messages are completed.