> considerations with regard to the following catalog
> performance options beyond the defaults
Eileen McClintock has done a presentation at SHARE about catalog tuning.
See if you can find it. She recommended (in 2007), among other things:
- Don't use anything larger than 8K CI size; this has
adverse index CI effects.
- Don't use VSAM freespace, and don't reorganize your
catalog; this undoes the benefits of any splits
that have already occurred.
- Don't let index CI size default; the system almost
always selects too small a control interval, which
leads to “dead” data control intervals that can't
be used in each control area. Allocate your index
in cylinders, not tracks.
- Shared catalog volumes kill you. Don't have
multiple catalogs on the same volume. Don't have
catalogs on shared volumes, period. In the latter
case every catalog lookup requires a VVR read,
regardless of whether the entry has been cached.
--
David Andrews
A. Duda and Sons, Inc.
[email protected]
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