FastSort Manual

Optimizing Sort Performance
FastSort Manual—429834-003
9-4
Using Scratch Files
DEFINE, FastSort automatically selects a scratch volume based on volume
characteristics. For more information about selection criteria, see How Volume
Characteristics Affect Selection on page 9-5.
How DEFINEs Affect Selection
You can specify volumes for FastSort to use or not use for scratch files with the
following attributes in a SORT DEFINE:

SCRATCH

SCRATCHON

NOSCRATCHON
FastSort uses these attributes, if they exist, to build a pool of scratch volumes by
inclusion and by exclusion. For more information on how to specify values for these
attributes, see Section 7, Using SORT and SUBSORT DEFINEs .
Figure 9-1 shows how FastSort uses DEFINEs to build a scratch volume pool.
FastSort first reads the SCRATCH attribute for the name of an initial scratch file or
scratch volume. If no SCRATCH file or volume is specified or if the file or volume
becomes full, FastSort reads the SCRATCHON attribute for acceptable overflow
Figure 9-1. How FastSort Reads Scratch Volume DEFINEs
SCRATCH NOSCRATCHONSCRATCHON
Inclusion Exclusion
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