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From: dansabrservices@yahoo.com (abrsvc)
Newsgroups: comp.os.vms
Subject: Re: RX2800 sporadic disk I/O slowdowns
Date: Tue, 5 Nov 2024 12:22:31 +0000
Organization: novaBBS
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Note:  Global buffers can be an advantage, but are not used when dealing
with duplicate secondary keys.  Those are handled in local buffers. I
have seen drastic differences in performance when changing bucket sizes
more with secondary keys that have many duplicates than with primary
keyed access.  Hein has some tools that analyze the statistics of
indexed files that report the number of I/Os per operation. High values
here can indicate inefficient use of buckets or buckets that are too
small forcing the use of more I/Os to retrieve buckets.  Increasing the
bucket size can significantly reduce I/Os resulting in better overall
stats.

This won't directly address the reported slowdown, but might be a
trigger for it depending upon data locality.

Dan