Cost

Enhanced Definition

Key Characteristics

- Resource-Centric: Costs are directly tied to the consumption of core mainframe resources such as CPU cycles (measured in MSUs or CPs), I/O operations (EXCPs), memory usage, and sometimes network bandwidth.
- SMF Data Driven: The underlying data for cost calculation is predominantly gathered by System Management Facilities (SMF) records, which capture detailed usage statistics for various system components and workloads.
- Chargeback/Showback Basis: Cost metrics are fundamental for implementing chargeback (billing internal departments or external clients for resource usage) or showback (reporting resource consumption without direct billing) models.
- Workload Specific: Costs can be attributed to specific jobs, started tasks, TSO users, CICS transactions, or DB2 queries, allowing for granular analysis of resource consumption.
- Software Licensing Impact: Beyond hardware resources, software license costs (e.g., for z/OS, DB2, CICS, IMS) are often a significant component, with pricing frequently linked to CPU consumption (e.g., MSUs).

Use Cases

- Departmental Chargeback: Allocating operational expenses to different business units based on their actual mainframe resource consumption, promoting accountability and cost awareness.
- Performance Optimization: Identifying resource-intensive applications, jobs, or transactions that are disproportionately consuming system resources, guiding efforts to optimize their efficiency (e.g., tuning COBOL programs, optimizing JCL).
- Capacity Planning: Forecasting future hardware and software requirements by analyzing historical resource usage trends and associated costs, ensuring sufficient capacity for growing workloads.
- Software License Management: Monitoring MSU consumption to manage and optimize software licensing costs, especially for products priced on a consumption basis.
- Budgeting and Financial Reporting: Providing accurate data for IT budgeting, financial forecasting, and demonstrating the value and cost-effectiveness of mainframe operations.

Related Concepts

Cost is intrinsically linked to System Management Facilities (SMF), which provides the raw data on resource usage. The Workload Manager (WLM) influences cost by managing resource allocation and prioritizing workloads, thereby affecting their consumption patterns. Metrics like Millions of Service Units (MSU) are a common unit for measuring CPU consumption and are a primary driver of both operational and software licensing costs. Effective cost management often relies on specialized chargeback systems or performance monitoring tools that process SMF data to generate usage reports and invoices.

Best Practices:

Regular SMF Data Analysis: Consistently collect, analyze, and report on SMF data to gain insights into resource consumption patterns and identify anomalies or inefficiencies.
Implement a Robust Chargeback/Showback System: Establish clear, transparent, and fair methodologies for attributing costs to consumers, fostering accountability and encouraging efficient resource use.
Optimize Workloads: Regularly review and optimize JCL, COBOL programs, DB2 queries, and CICS transactions to reduce their CPU, I/O, and memory footprint, directly lowering operational costs.
Leverage WLM Effectively: Configure WLM service definitions to align with business priorities, ensuring critical workloads receive necessary resources while managing less critical ones efficiently to control overall consumption.
Monitor Software Licensing: Proactively monitor MSU consumption against software license agreements to avoid overage charges and identify opportunities for license optimization or renegotiation.