Optimizing System Performance

Overview of Optimizing OpenVMS System Performance

All software users are concerned about system speed and resource consumption. This section provides suggestions that might increase performance and reduce resource consumption in the OpenVMS operating environment. Suggestions are grouped by SAS function: data set I/O, external file I/O, and system start-up.

SAS performance partially depends on the performance of the underlying OpenVMS environment. This document does not discuss how to improve the performance of your OpenVMS environment, but it does offer some suggestions, such as installing SAS images, that can aid OpenVMS system-wide performance.

Note: This section does not discuss OpenVMS hardware solutions to problems that are related to I/O. [cautionend]

The suggestions described here are based on testing on an OpenVMS workstation with 64MB of memory and an attached SCSI disk drive. Both SAS performance data that is generated by the STIMER system option and information from the DCL SHOW STATUS command were used to collect data points.

Each suggestion includes the following information in a tabular summary at the beginning of each section:

Job type	is the type of SAS application affected.
User	is the person(s) who can implement the suggestion.
Usage	is a usage example.
Benefit	describes the potential benefits.
Cost	is the cost in system performance.

Use this information to help you decide which suggestions are suitable for your SAS applications.

Most of these suggestions have an associated cost, which can often involve a tradeoff between resources. For example, reduced I/O might require more memory consumption or greater CPU time. Pay careful attention to the possible costs of each suggestion. Some suggestions can cause performance degradation if they are misapplied.

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