|
HP OpenVMS Systemsask the wizard |
|
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.
|