Browse Prior Art Database

ICF Catalog Sharing Protocol at Record Key Granularity

IP.com Disclosure Number: IPCOM000109772D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Related People

Plow, GM: AUTHOR [+2]

Abstract

This invention relates to a multi-CPU (central processing unit) shared catalog environment wherein a method communicates the key of any modified record to all sharing systems and permits the retention of all other cached records. Previous methods required all sharing systems to invalidate all cached catalog records.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

ICF Catalog Sharing Protocol at Record Key Granularity

       This invention relates to a multi-CPU (central processing
unit) shared catalog environment wherein a method communicates the
key of any modified record to all sharing systems and permits the
retention of all other cached records.  Previous methods required all
sharing systems to invalidate all cached catalog records.

      When ICF catalogs are shared among multiple systems, older
protocols provide each system with the minimum information required
to keep the catalog control blocks for each system in
synchronization.  Three VVRs (virtual storage access method volume
records) are read from DASD (direct access storage device) to obtain
this information.  Any change made to the ICF catalog (e.g., via ADD,
UPDATE or ERASE) requires all sharing systems to invalidate any
catalog records they may have cached in storage to insure that
downlevel records are not used.  This presents a severe performance
limitation to the utility of caching.

      This invention proposes a method which only requires reading
one VVR to maintain control block synchronization, and to communicate
complete details about any changes to the ICF catalog.  As a result,
only the modified record of a cached catalog needs to be invalidated.

      The new sharing protocol introduces a "sharing subcell" record
in the ICF catalog data VVR.  This record holds all the information
necessary to successfully share the catalog as a VSA...