Abstract: Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.

Abstract: Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.

Abstract: Repositioning within an input/output device is accomplished without any knowledge of where the input/output device is currently positioned. The input/output device is repositioned to a predetermined position, in order for a program to be retried. The predetermined position is determined from a previously executed program. The previously executed program is scanned looking for commands. For each command found, a position identifier is adjusted based upon the type of command. When the scan and adjustments are complete, the position identifier represents the predetermined position used for repositioning the input/output device.

Abstract: A system for prestaging data into a cache to increase the speed data is received from a direct access storage drive (DASD) is utilized within a data processing system. This system utilizes multi-track read operations to prestage tracks into the cache. In so doing, the overhead associated with proceeding from one track to the next is reduced. The system allows for the prestaging of up to a cylinder of tracks per prestage. The prestaging system will also allow internally scheduled operations requiring a physical device to interrupt the prestaging if conditions require this action to maintain subsystem performance.

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.