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The Question is:
Hi,
I would like some clarification on directory peformance improvements in 7.2,
specifically related to the insertion and deletion of files in very large
directories.
The release notes for OpenVMS 7.2, section 5.20.1.3 relates to an improvement
in performance of wildcard lookups in large directories by the elmination of
cache size restriction.
In the OpenVMS FAQ (FILE4.) and Ask the Wizard article 5241, there is an
implication that the performance improvements in large directory operation is
not limited to wild card lookups but also includes other directory operations
such as deletion and inser
tion.
Am I reading too much into the FAQ & Ask the Wizard article or are the release
notes incomplete (or maybe I missed the pertinent information in the release
notes).
Also, other sources are mentioning a cache limit size of 1024 blocks instead of
127. Is 1024 associated with some other or related cache size?
The Answer is :
The improvement is in any operation that involves modifications to
the directory contents (insertion, deletion), as well as operations
that involve scanning through (larger) directory files.
The directory improvements are due to two different and distinct
changes: the I/O operations that are used for directory updates
now use rather larger block sizes, and the size of the directory
cache itself has been greatly increased. The former is of more
interest during insertions and deletions, while the latter tends
to benefit searches...
The directory cache is now limited by process quotas, and is
largely now based on a combination of the available PGFLQUOTA and
the size of the pool reserved by the system IMGIOCNT parameter.
There are other enhancements in this area, as well. BITMAP, the
packing of entries in directories, etc.
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