Guide to OpenVMS Performance Management

This manual is a conceptual and tutorial guide for experienced users and system managers responsible for optimizing performance on OpenVMS systems. Published in May 1993, it provides techniques for evaluating, analyzing, and optimizing hardware and software resources on VAX configurations.

The document covers:

• Performance Management Introduction: Understanding workload, evaluating user complaints, and establishing performance investigation and tuning strategies.
• OpenVMS Resource Management Review: Detailed explanations of memory management mechanisms like automatic working set adjustment (AWSA), swapper trimming, memory sharing, and process scheduling, as well as the policy of proactive memory reclamation.
• Managing System Resources: How to use utilities like MONITOR and ACCOUNTING to collect and analyze data on CPU, memory, and disk I/O resources, and strategies for improving responsiveness, equitable sharing, load balancing, and offloading.
• Diagnosing Resource Limitations: Step-by-step procedures, including decision-tree diagrams, to investigate and isolate performance bottlenecks caused by memory, I/O, or CPU limitations.
• Compensating for Resource Limitations: Corrective procedures and recommendations for tuning system parameters, adjusting working set characteristics, managing page and file system caches, reducing interrupts, and determining when hardware upgrades are necessary.

The manual emphasizes that effective performance management involves a thorough understanding of system behavior, careful monitoring of changes, and a cautious, iterative approach to tuning. It also highlights that hardware limitations, particularly insufficient memory, are often the root cause of performance problems that cannot be solved by software tuning alone.