Browse Prior Art Database

Automatic Generation of Record 0 from Extended Count Key Data Emulated on Optical Disks

IP.com Disclosure Number: IPCOM000110839D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Day, K: AUTHOR [+2]

Abstract

A method for automatically generating a Record 0 on Extended Count Key devices is disclosed. Special cases where a Record 0 does not exist are also handled.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

Automatic Generation of Record 0 from Extended Count Key Data Emulated
on Optical Disks

      A method for automatically generating a Record 0 on Extended
Count Key devices is disclosed.  Special cases where a Record 0 does
not exist are also handled.

      In Extended Count Key Data (ECKD) Direct Access Storage Device
(DASD) architecture, a "standard" (no key, data length of 8, data all
zeros) is usually stored on the DASD.  In fact, most DASD access
methods enforce this.  This record is used (along with the Home
Address (HA) record) for surface defect management and for track
orientation.  When ECKD DASD is emulated with Optical Disks, defect
management and orientation will be handled by different mechanisms,
therefore, eliminating the need for a standard RO.  This disclosure
describes a method to eliminate RO records from emulated DASD tracks
written on ECKD optical disks while still allowing for the rare case
of a non-standard RO.

      Although RO is not required for defect management or
orientation, existing access methods reference these fields and
expect them to be present.  Therefore, the appearance must be created
of having an RO without wasting the space (or time) to actually have
the record in the track image.

      All ECKD records have a count field.  This count field
describes the record that it is part of.  Furthermore, every count
field contains information that is global (relates to the track image
itself rather than that particu...