Browse Prior Art Database

A Method to Encapsulate a Channel Program and Execute this Channel Program as an I/O Packet

IP.com Disclosure Number: IPCOM000109136D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 53K

Publishing Venue

IBM

Related People

McHenry, LE: AUTHOR

Abstract

Disclosed is a "channel program streaming" protocol for serial channel architecture by which a direct access storage device (DASD) program is transferred as a "packet" across the I/O interface to DASD subsystems. This packet is stored in memory and comprises command words which are then executed from memory. The transfer of an entire set of commands, improves channel efficiency by eliminating the turnaround time required for word by word transfers. The I/O channel would only be involved in read or write data transfers and the necessary I/O protocol to achieve these transfers. If enough memory is provided on the subsystem, even write data may be included in the packet, enabling reading from this memory.

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A Method to Encapsulate a Channel Program and Execute this Channel Program as an I/O Packet

      Disclosed is a "channel program streaming" protocol for serial
channel architecture by which a direct access storage device (DASD)
program is transferred as a "packet" across the I/O interface to DASD
subsystems.  This packet is stored in memory and comprises command
words which are then executed from memory.  The transfer of an entire
set of commands, improves channel efficiency by eliminating the
turnaround time required for word by word transfers.  The I/O channel
would only be involved in read or write data transfers  and the
necessary I/O protocol to achieve these transfers.  If enough memory
is provided on the subsystem, even write data may be included in the
packet, enabling reading from this memory.

      The program packet may contain count key data, extended count
key data, or fixed block architecture channel programs.  A packets
may also contain more than one channel program.  Alternatively,
programs may be extended by "chain scheduling," where subsequent
packets of command words are transferred during execution and
appended to the original channel program in memory.

      "Channel program streaming" facilitates communication between
DASD subsystems.  A central processing complex (CPC) sends two
channel program packets to two of its DASD subsystems.  Each packet
contains identification for the other subsystem so that communication
can be establ...