Browse Prior Art Database

Dynamic Key-Boundary Multi-Cluster Virtual Sequential Access Method Data Sets

IP.com Disclosure Number: IPCOM000122929D
Original Publication Date: 1998-Jan-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Ashton, LL: AUTHOR [+3]

Abstract

Disclosed is a process to dynamically calculate and maintain the key boundaries of a multi-cluster key-sequenced Virtual Sequential Access Method (VSAM) data set. This process enables data sets that were previously defined as key-ranged to continue to use multiple clusters without suffering the limitations associated with Key-Ranged VSAM Data Sets (KRDS).

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Dynamic Key-Boundary Multi-Cluster Virtual Sequential Access Method
Data Sets

      Disclosed is a process to dynamically calculate and maintain
the key boundaries of a multi-cluster key-sequenced Virtual
Sequential Access Method (VSAM) data set.  This process enables data
sets that were previously defined as key-ranged to continue to use
multiple clusters without suffering the limitations associated with
Key-Ranged VSAM Data Sets (KRDS).

      The key-range format of VSAM data sets offers an advantage over
other formats of VSAM data sets in that each of the individual
clusters that compose a KRDS can be processed individually.  This
enables functions, such as data set backup, to process individual
clusters in parallel.  This also allows functions, such as data set
recover, to process a single cluster without having to process the
entire data set.  This allows for tremendous performance advantages.
But, key-ranged  format data sets are limited in that many VSAM
features do not support  the key-range format.  The following process
enables applications to continue to use multi-cluster key-sequenced
data sets for the advantages  that they offer, without suffering the
limitations associated with the  key-range VSAM format.

      For a key-sequenced data set that is defined with multiple
clusters and no key-ranges, the key boundaries are dynamically
calculated using the following steps:
  1.  The low key of the first cluster is set to '00'X.
  2.  The...