Input/Output Configuration Program: Difference between revisions

Revision as of 13:20, 29 May 2023

Revision as of 14:37, 29 May 2023

Line 40:

| id = SA22-7085-1

| version = Second Edition

| date = January 1987}}</ref> mode, IBM changed the I/O architecture to allow the [[Channel Subsystem]] to handle the channel scheduling that the operating system had to handle in S/370 mode. The new I/O architecture used a 16-bit '''subchannel number''', a 16-bit '''device number''' and an 8-bit '''Channel Path Identifier''' ('''Channel Path Id''' or '''CHPID'''); the [[Channel Subsystem]] was responsible for mapping the '''subchannel number''' to the channel and device numbers, for queuing I/O requests and for selecting from the available paths.

Starting with [[IBM z#IBM zSeries family|z990]], IBM introduced the concept of a '''Logical Channel Subsystem'''<ref>{{cite manual

Line 53:

| access-date = May 29, 2023

}}

</ref> ('''LCSS'''); each physical channel (of 1024) has a unique '''Physical Channel Path Identifier''' ('''PCHPID'''), each LCSS has a CHPID to PCHPID mapping and each LPAR is assigned to one LCSS.

Starting with [[System z9]] running [[z/OS]] 1.7, IBM offered the multiple-subchannel set facility, which allowed up to four independent sets of 64 Ki subchannels.<ref>{{cite manual

Line 64:

</ref>

The installation was responsible for defining the [['''Input/Output Configuration Data Set]]'''s ('''IOCDS''''s), and the operator could select a specific '''IOCDS''' as part of a [[power on reset]] (POR). '''Input/Output Configuration Program''' ('''IOCP''')<ref name=GC38-0097/><ref name=GC38-0401/><ref name=GC38-0456/> is a program for IBM mainframes that compiles a description of the [[Channel Subsystem]] and [[LPAR]]<ref name=GA22-7123/> configuration, optionally loading it into an [[Input/Output Configuration Data Set]] (IOCDS); it recognizes the syntax of [[MVS Configuration Program]] (MVSCP)<ref name=GC28-1615/> input, and there is no need to maintain separate input files.

The direct use of IOCP and [[MVS Configuration Program|MVSCP]] has been mostly supplanted by Hardware Configuration Definition<ref name=GA22-7525/>(HCD).