High Performance

Enhanced Definition

Key Characteristics

- Exceptional Throughput: Ability to process a massive volume of transactions or batch jobs per second/minute, crucial for large-scale enterprise operations.
- Low Latency and Response Time: Minimizing the delay between a request and its corresponding response, vital for interactive online transaction processing (OLTP) systems like CICS.
- Scalability: The capacity to handle increasing workloads by adding resources (e.g., processors, memory, I/O channels) without significant degradation in performance.
- Resource Optimization: Efficient utilization of CPU, memory, I/O, and network resources through advanced features like z/OS Workload Manager (WLM) and specialized processors (zIIP, zAAP).
- Reliability and Availability: High-performance systems on z/OS are inherently designed for continuous operation, ensuring that performance levels are sustained even under extreme loads or component failures.
- Parallel Processing Capabilities: Leveraging multi-core processors, Parallel Sysplex technology, and concurrent execution to distribute and accelerate workload processing.

Use Cases

- Online Transaction Processing (OLTP): Ensuring sub-second response times for millions of concurrent transactions in systems like CICS or IMS TM, critical for banking, airline reservations, and retail.
- High-Volume Batch Processing: Rapidly processing large datasets for end-of-day reconciliations, payroll runs, billing cycles, and data transformations using JCL and COBOL batch programs.
- Enterprise Data Management: Providing fast and efficient access to vast amounts of data stored in DB2, IMS DB, or VSAM, supporting complex queries and data updates.
- Real-time Analytics and Reporting: Executing complex analytical queries against operational data stores with minimal impact on transactional workloads, often leveraging specialized processors.
- Middleware and Integration: Supporting high-speed message queuing (MQ) and integration services for connecting diverse applications across the enterprise.

Related Concepts

High performance on z/OS is intrinsically linked to Workload Manager (WLM), which dynamically manages system resources to meet defined performance goals for different workloads. It is heavily reliant on Parallel Sysplex technology for scalability and continuous availability, allowing multiple z/OS images to share data and resources. Specialized processors like zIIPs (IBM z Integrated Information Processors) and zAAPs (IBM z Application Assist Processors, now integrated into zIIPs) offload specific workloads (e.g., DB2 queries, Java) to improve performance and reduce general-purpose CPU consumption. Application design, efficient COBOL code, optimized JCL for I/O and data management, and well-tuned DB2 or IMS databases are fundamental to achieving and sustaining high performance.

Best Practices:

WLM Policy Tuning: Regularly review and adjust WLM service definitions and goals to ensure critical workloads receive priority and adequate resources, balancing performance across the system.
Application Optimization: Profile and optimize COBOL, PL/I, or Java application code, focusing on efficient algorithms, minimizing I/O operations, and leveraging system services effectively.