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Pointer-Implemented CKD Track Format

IP.com Disclosure Number: IPCOM000111423D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Wada, S: AUTHOR

Abstract

This article describes a record pointer-implemented Count-Key-Data (CKD) track format suitable for a disc subsystem, such as a disc array, a semiconductor disc subsystem, and so on, which emulates the conventional CKD track format. The pointer implemented in this format can address directly the record to be processed by a channel command from a host when the whole record of a track resides on the buffer memory in the disc subsystem.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Pointer-Implemented CKD Track Format

      This article describes a record pointer-implemented
Count-Key-Data (CKD) track format suitable for a disc subsystem, such
as a disc array, a semiconductor disc subsystem, and so on, which
emulates the conventional CKD track format.  The pointer implemented
in this format can address directly the record to be processed by a
channel command from a host when the whole record of a track resides
on the buffer memory in the disc subsystem.

      Fig. 1 shows the sample of the new format.  This track format
is generated in the buffer memory and then stored in storage devices
in the disc  subsystem.  The record pointer area (1-1) is the area
where a pointer to each record in the record area (1-2) is stored
adjacently.  The record pointers are generated, updated, or deleted
in the process of a format write command from a host.

      Fig. 2 shows the detailed relation between a pointer and a
record.  The n'th pointer Pn consists of PnS which indicates the
start position of the n'th record Rn and PnE which indicates the end
position of it.  The n'th record Rn normally consists of a count area
RnC, a key area RnK, and a data area RnD.  The number of the n is the
integer from 0 to maximum 255.  In detail, the P0S of the first
pointer of P0 contains the start position of the 0th record R0 and
the P0E contains the end position of it.

      The existence or no existence of a record can be recognized
with the pointer and...