Abstract: A method, system, and computer program product are provided for determining whether a control unit for an attached device has lost knowledge of a supported host enabled facility associated with the attached device. I/O instructions are initiated that include a first instruction to determine whether the control unit currently has knowledge of the host enabled facility and a second instruction providing knowledge of the host enabled facility by the control unit. Based on responses from the control unit to the I/O instructions, it is determined whether the control unit has transitioned from not having knowledge of the host enabled facility to having such access. If it is determined that the control unit has made such transition as a result of the sequence of I/O instructions, parameters for use with the host enabled facility are initialized; otherwise, such initialization is prevented.

Abstract: A method, system, and computer program product are provided for determining whether a control unit for an attached device has lost knowledge of a supported host enabled facility associated with the attached device. I/O instructions are initiated that include a first instruction to determine whether the control unit currently has knowledge of the host enabled facility and a second instruction providing knowledge of the host enabled facility by the control unit. Based on responses from the control unit to the I/O instructions, it is determined whether the control unit has transitioned from not having knowledge of the host enabled facility to having such access. If it is determined that the control unit has made such transition as a result of the sequence of I/O instructions, parameters for use with the host enabled facility are initialized; otherwise, such initialization is prevented.

Abstract: A method for maintaining data integrity of a storage device is provided. A request is received to create an access monitoring session for a data range on a volume of the storage device. A session identification (ID) is determined for the access monitoring session for data range on the volume. An entry is created in an access monitoring session table for the session ID, and the entry adds the access monitoring session with session ID for the data range on the volume to the access monitoring session table. Request parameters are included in the request to create the access monitoring session. The request parameters denote access to the data range on the volume for the session ID and are stored in the access monitoring session table. Access is controlled to the data range on the volume for the session ID based on request parameters stored in the access monitoring session table.

Abstract: A method for maintaining data integrity of a storage device is provided. A request is received to create an access monitoring session for a data range on a volume of the storage device. A session identification (ID) is determined for the access monitoring session for data range on the volume. An entry is created in an access monitoring session table for the session ID, and the entry adds the access monitoring session with session ID for the data range on the volume to the access monitoring session table. Request parameters are included in the request to create the access monitoring session. The request parameters denote access to the data range on the volume for the session ID and are stored in the access monitoring session table. Access is controlled to the data range on the volume for the session ID based on request parameters stored in the access monitoring session table.

Abstract: In a multi-system complex having central processing complexes (CPCs) and subsystems, a hardware facility for prompt interdicting I/O and message operations. A CPC or subsystem failure causes as interruption in the availability of the data bases to the attached network of terminals. Often such networks have thousands of terminals. Even a short loss of data is detrimental. Therefore the CPC or subsystem takeover must be accomplished as quickly as possible and the I/O attached to the failing CPC or subsystem must be interdicting to release it for use to the rest of the complex. The disclosed hardware facility provides a mechanism which is program initiated and controlled and which guarantees the prompt completion of the interdiction function.

Abstract: An I/O request time limit value is set in a request-based, device-based, data-set-based, or workload-based time limit field, for transactions performing I/O operations to I/O devices in a data processing system. A scan routine compares the total time for the I/O request (including waiting time and retry time) against the appropriate time limit(s), and terminates the I/O request if the time limit is exceeded. If an active I/O request is interrupted as a result of an I/O error, retry is prohibited if the total I/O request time (including retry time) exceeds the appropriate time limit, or is within a threshold value of the appropriate time limit.