IFI - Instrumentation Facility Interface

Enhanced Definition

The Instrumentation Facility Interface (IFI) is a programmatic interface provided by IBM DB2 for z/OS that allows external applications to access a wide range of internal DB2 performance, accounting, statistics, and trace data. It serves as the primary mechanism for monitoring, analyzing, and diagnosing the health and activity of DB2 subsystems on the mainframe.

Key Characteristics

- Programmatic API: IFI is a callable service that can be invoked by user-written programs (e.g., COBOL, C/C++, Assembler) or commercial monitoring tools.
- Comprehensive Data Access: Provides access to detailed DB2 instrumentation data, including accounting records, statistics, system parameters, buffer pool activity, SQL statement execution, lock contention, and more.
- Real-time and Batch Capabilities: Can be used for real-time monitoring of active DB2 subsystems or for post-processing of collected data, often written to SMF records.
- Control over Traces: Allows applications to start, stop, and retrieve data from various DB2 traces (e.g., accounting, statistics, performance, audit, monitor).
- Data Formats: Data is returned in specific DB2 DSECT (Data Section) formats, requiring applications to understand the structure of the returned control blocks.
- DB2-Specific: Exclusively designed for and integrated with IBM DB2 for z/OS environments.

Use Cases

- Performance Monitoring: Commercial and custom tools use IFI to provide real-time dashboards and alerts on DB2 subsystem health, resource utilization, and application performance.
- Problem Determination: Diagnosing performance bottlenecks, SQL statement inefficiencies, deadlocks, latch contention, and other operational issues within DB2.
- Capacity Planning: Collecting historical performance data to analyze trends, predict future resource requirements, and optimize DB2 configurations.
- Auditing and Security: Monitoring specific DB2 events, user activities, or data access patterns for compliance, security audits, or anomaly detection.
- Custom Application Development: Building specialized tools for specific operational needs, such as automated reporting, workload analysis, or integration with enterprise management systems.

Related Concepts

IFI is fundamental to understanding and managing DB2 for z/OS. It is the underlying mechanism that allows most DB2 monitoring tools (like IBM OMEGAMON for DB2, BMC MainView for DB2, CA Detector) to gather their data. While much of the data accessible via IFI can also be written to SMF (System Management Facilities) records, IFI provides a more direct, real-time, and granular interface for data retrieval and trace control. It works in conjunction with DB2 traces (e.g., accounting trace, statistics trace, performance trace) by enabling their activation and the retrieval of their output.

Best Practices:

Selective Tracing: Only activate the necessary DB2 traces and IFI calls to minimize overhead on the DB2 subsystem, especially in production environments.
Efficient Data Retrieval: Design IFI applications to retrieve data efficiently, using appropriate IFI functions (e.g., DSNWFI calls) and filtering options to reduce data volume and processing.
Resource Management: Be mindful of the CPU, memory, and I/O resources consumed by IFI applications, as excessive activity can impact DB2 performance.
Error Handling: Implement robust error handling and recovery mechanisms in any custom IFI application to ensure stability and proper data collection.
Security Considerations: Restrict access to IFI applications and the data they collect, as IFI can expose sensitive performance and operational details of the DB2 environment.