Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Locate Record Extended Command - A More Versatile DASD Access Command

IP.com Disclosure Number: IPCOM000106199D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Henry, BM: AUTHOR [+3]

Abstract

The Locate Record command in ECKD* defines a highly structured DASD I/O access model for programs to request simple data transfer operations of CKD track format DASD. Advances in DASD subsystem capability along with the increasing need for non-gap-synchronous operations requires a more comprehensive message-type command instruction format for a program to request complex data transfer operations from an ECKD DASD subsystem -- a requirement that cannot be fulfilled by the Locate Record command. To meet this requirement and retain compatibility with and the structure of the ECKD Locate Record channel, a new Locate Record Extended channel command word is described.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 81% of the total text.

Locate Record Extended Command - A More Versatile DASD Access Command

      The Locate Record command in ECKD* defines a highly structured
DASD I/O access model for programs to request simple data transfer
operations of CKD track format DASD.  Advances in DASD subsystem
capability along with the increasing need for non-gap-synchronous
operations requires a more comprehensive message-type command
instruction format for a program to request complex data transfer
operations from an ECKD DASD subsystem -- a requirement that cannot
be fulfilled by the Locate Record command.  To meet this requirement
and retain compatibility with and the structure of the ECKD Locate
Record channel, a new Locate Record Extended channel command word is
described.  This command provides the capability of defining a domain
within which data transfer operations that do not meet the
traditional definition of well structured access requests can operate
while also supporting all of the operations of the Locate record
command.  It effectively brings the message-command-type of
communication that may be generally found in non-S/370*,
non-CKD-track-format DASD I/O enviroments, into S/370 and S/390* I/O
and DASD

      The Locate Record Extended channel command word contains a
variable length parameter list (20 to 65,535 bytes).  The first 16
bytes are the same as defined for the base ECKD Locate Record CCW.
The remaining bytes of the parameter define the length and content of
the message-type e...