On 04/04/2012 10:37 AM, Chip Grantham wrote:
We have an application like this, that is multiple record types in the
same KSDS. We found that if we had a FD for the type '4' records and a FD
for the type '5' records (that is two DDs pointing to the same file), that
each kept a separate sequence set in storage and it ran faster. You might
try it.
Chip Grantham | Ameritas | Sr. IT Consultant | cgrant...@ameritas.com
5900 O Street, Lincoln NE 68510 | p: 402-467-7382 | c: 402-429-3579 | f:
402-325-4030
...
Unless you have something at your installation that automatically tunes
VSAM buffer allocation, some kind of manual tuning in the JCL is almost
always recommended, as the default VSAM buffer allocations tend to be
terrible for performance. Just specifying an BUFFNI INDEX buffer count
large enough to accommodate all index levels, plus additional buffers if
the access pattern has multiple localities of reference, can do wonders
for random access performance, even without going to BLSR. The default
used to "guarantee" that random access to any VSAM file with data in
more than one CA (and hence at least two levels of index) would require
re-reading CI's for all the various index levels for each data record
access. Just providing a few additional index buffers in such cases
might be enough to cut the physical I/O's by a significant factor.
--
Joel C. Ewing, Bentonville, AR jcew...@acm.org
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