HP OpenVMS Systems

V7.2 Directory I/O, Cache Improvements?

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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.
 
 

  

     

     
answer written or last revised on ( 10-MAY-2001 )
     
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