Browse Prior Art Database

Automatic Generation of Home Address Record

IP.com Disclosure Number: IPCOM000111002D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Day, K: AUTHOR [+2]

Abstract

Described is a method to eliminate Home Address records from emulated DASD tracks written on Extended Count Key Data Optical Disks.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 67% of the total text.

Automatic Generation of Home Address Record

      Described is a method to eliminate Home Address records from
emulated DASD tracks written on Extended Count Key Data Optical
Disks.

      Described here is a process for eliminating the need to write
Home Address (HA) records on emulated DASD tracks written to Extended
Count Key Data (ECKD) Optical Disks while allowing the READ, WRITE,
and SEARCH HA commands to be implemented.  This method will increase
the amount of space available to the customer and shorten the time
required to stage or destage an emulated DASD track.

HA records are needed on DASD for two primary reasons:

o   for orientation to the beginning of the track

o   to hold data related to defective and alternate tracks

      Emulated DASD tracks on Optical Disk will be staged to main
storage before any orientation will take place.  Therefore,
orientation will actually consist of moving pointers through storage.
A logical beginning of track will be maintained without an actual
physical place holder.  Defective and alternate tracks are tied
directly to the DASD media.  Optical media manages defective sectors
within the device microcode.  Therefore, the emulated track image
does not need to contain any defective or alternate information.

Five parameter bytes are read, written, or searched for these
commands:

o   1 Byte of Flag information (must be zero on ECKD Optical Disks)

o   2 Bytes of Cylinder (must be equal to the actual cylinder)

o...