Browse Prior Art Database

Technique for Resetting a Single Channel Path Under Operator Control in IBM System/370xa

IP.com Disclosure Number: IPCOM000042036D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

McGee, HT: AUTHOR

Abstract

This technique allows an IBM System/370XA operator to reset a single channel path, without causing any data integrity or performance problems due to devices being reserved to the specified channel path or devices having the specified channel path in a dynamic pathing group. A menu option is provided on the operator console of a machine operating in XA mode to allow the operator to designate the channel path identifier (CHPID) of a channel path that is to be reset. When a valid CHPID is entered, the program is presented with a new type of channel report word (CRW), "RCHP requested" CRW, for the designated channel path.

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Technique for Resetting a Single Channel Path Under Operator Control in IBM System/370xa

This technique allows an IBM System/370XA operator to reset a single channel path, without causing any data integrity or performance problems due to devices being reserved to the specified channel path or devices having the specified channel path in a dynamic pathing group. A menu option is provided on the operator console of a machine operating in XA mode to allow the operator to designate the channel path identifier (CHPID) of a channel path that is to be reset. When a valid CHPID is entered, the program is presented with a new type of channel report word (CRW), "RCHP requested" CRW, for the designated channel path. The program then performs its channel path recovery functions (which includes clearing any I/O that is active on the designated channel path, moving reserve allegiances from the designated channel path to other channel paths, and notifying the operator to stop sharing processors, if necessary) and issues an RCHP instruction for the channel path. (The RCHP instruction requests the channel subsystem to signal system reset over the designated channel path.) The channel subsystem notifies the program of the results of the system reset via an "initialized" or "permanent" CRW. The program then completes its channel path recovery functions (which includes re-reserving devices, resinstating the reset channel path back into dynamic pathing groups, and notifying the opera...