Browse Prior Art Database

DFDSS Multi-volume VSAM Define

IP.com Disclosure Number: IPCOM000109774D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Bushman, DJ: AUTHOR [+2]

Abstract

Two methods are disclosed for using Data Facility Data Set Services (DFDSS) to process virtual storage access method (VSAM) data sets requiring allocation of more than a single output volume.

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This is the abbreviated version, containing approximately 92% of the total text.

DFDSS Multi-volume VSAM Define

       Two methods are disclosed for using Data Facility Data
Set Services (DFDSS) to process virtual storage access method (VSAM)
data sets requiring allocation of more than a single output volume.

      To process a data set, DFDSS first allocates space on the DASD
(direct access storage device) output volume, and then writes tracks
until all of the data is in place.  Because it operates at a physical
track level rather than using an access method to write logical
records, there is no way for DFDSS to extend the data set beyond its
initial allocation amount.  It must therefore allocate enough space
to contain the data set in its entirety.

      DFDSS may allocate space on more than one volume for non-VSAM
data sets too large to fit on any one output volume.  However, VSAM
data sets use a different allocation method which restricts DFDSS
from processing such data sets larger than a single volume.

      Data Facility Product Version 3.1.0 (DFP V3.1.0), when used in
conjunction with DFDSS, allows preallocation of space on multiple
volumes for all VSAM data sets other than KSDS (key sequence data
sets) with keyranges. Once the space is allocated, DFDSS track
packing is employed to write tracks until the data is in place.

      Alternatively, where DFP V3.1.0 is not available or the
multivolume data set is keyed, DFDSS allocates the data set on a
single volume and defines candidate volumes for overflow.  Data is
writt...