Job Accounting - Usage recording

Enhanced Definition

Job accounting, in the z/OS context, refers to the systematic process of collecting, recording, and analyzing resource utilization data for all types of work executing on the system, including batch jobs, started tasks, and TSO user sessions. Its primary purpose is to track system resource consumption for purposes such as chargeback, capacity planning, performance analysis, and auditing.

Key Characteristics

- Comprehensive Data Collection: Gathers detailed metrics on CPU time, I/O operations (EXCP counts), memory usage, elapsed time, print lines, network activity, and other system resources consumed by a workload.
- SMF Records: Primarily relies on System Management Facilities (SMF) records, particularly SMF Type 30 (common address space work), Type 4 (step termination), Type 5 (job termination), and other specific types (e.g., Type 42 for DASD activity, Type 70-79 for RMF data).
- System-wide Scope: Applies to virtually all work running under z/OS, providing a holistic view of resource consumption across the entire mainframe environment.
- Post-processing Required: Raw SMF data, stored in SMF data sets, must be offloaded and processed by utility programs (e.g., IFASMFDP) or specialized accounting software to generate meaningful reports.
- Configurable: The types of data collected, the frequency of collection, and the specific SMF records written can be extensively configured via the SMFPRMxx member in SYS1.PARMLIB.

Use Cases

- Chargeback and Billing: Allocating IT costs to specific business units, departments, or projects based on their actual consumption of mainframe resources, enabling fair and transparent cost recovery.
- Capacity Planning: Analyzing historical resource usage trends to forecast future demands, identify potential bottlenecks, and plan for necessary hardware, software, or network upgrades.
- Performance Analysis and Optimization: Identifying resource-intensive jobs, inefficient applications, or peak usage periods that might be impacting overall system performance, guiding tuning efforts.
- Auditing and Compliance: Providing a detailed audit trail of system resource usage, job execution, and user activity, which is crucial for regulatory compliance and security audits.
- Resource Management: Helping system administrators and developers understand how applications consume resources, facilitating better resource allocation and workload management decisions.

Related Concepts

Job accounting is intrinsically linked to SMF (System Management Facilities), which is the foundational mechanism z/OS uses to record virtually all system activity and resource usage. While Workload Manager (WLM) manages system resources to meet performance goals, job accounting provides the granular data to verify if those goals are being met and to understand the actual resource footprint of WLM-managed workloads. It also complements Performance Monitoring Tools like RMF (Resource Measurement Facility) by providing the underlying data that these tools often analyze to present performance insights and trends.

Best Practices:

Comprehensive SMF Configuration: Ensure SMFPRMxx is configured to capture all relevant SMF record types, especially Type 30, to provide a complete picture of resource consumption for all workloads.
Automated SMF Data Management: Implement robust, automated procedures for offloading, merging, and backing up SMF data sets regularly to prevent data loss and ensure continuous data availability for processing.
Consistent Accounting Information: Enforce standards for including meaningful accounting information (e.g., project codes, department IDs) in JOB statements using the ACCOUNT parameter to facilitate accurate chargeback and reporting.
Regular Data Processing and Reporting: Utilize IFASMFDP or third-party accounting software to regularly process raw SMF data into actionable reports, enabling timely analysis and decision-making.
Data Retention Policy: Establish and adhere to a clear data retention policy for processed accounting data to meet historical analysis, auditing, and compliance requirements.