Growth

Enhanced Definition

In the mainframe context, **growth** refers to the increase in size, capacity, or demand for various system resources, data storage, application workloads, or infrastructure components over time. It is a critical factor in capacity planning, performance management, and resource allocation within the z/OS environment.

Key Characteristics

- Varied Manifestations: Can apply to data sets (e.g., VSAM, sequential), database objects (e.g., DB2 tablespaces, IMS segments), log files (e.g., SMF, system logs), storage volumes, CPU utilization, real storage (memory) consumption, and transaction volumes.
- Predictable vs. Unpredictable: Some growth, like log file accumulation or planned data retention, is predictable. Other growth, such as unexpected workload spikes or rapid application data expansion, can be unpredictable and requires agile management.
- Resource Consumption: Directly impacts the consumption of critical mainframe resources, including DASD (Direct Access Storage Device) space, CPU cycles, real storage, and I/O channels.
- Management Imperative: Requires proactive monitoring, forecasting, and management strategies to prevent resource exhaustion, performance degradation, and potential system outages.
- Cumulative Effect: Small, continuous increases across multiple areas can lead to significant overall system growth, necessitating periodic re-evaluation of system architecture and resource provisioning.

Use Cases

- Data Set Expansion: A VSAM KSDS file grows as new records are added, requiring monitoring of free space and potential reorganization or allocation of larger extents through JCL modifications or utilities.
- Database Growth: A DB2 table experiences growth as application transactions insert new rows, necessitating regular checks of tablespace size and potential ALTER TABLESPACE operations to increase primary or secondary allocations.
- Workload Increase: An online CICS application experiences a surge in transaction volume during peak business hours, leading to increased CPU usage and I/O operations, which must be managed through WLM policies.
- Log File Accumulation: SMF records, system logs, and CICS journal files continuously grow, requiring automated offloading, archiving, and deletion processes to manage DASD space and ensure data availability.
- Storage Volume Saturation: Multiple data sets growing on a single DASD volume can lead to the volume becoming full, requiring data migration, allocation of new volumes, or re-tiering using DFSMS.

Related Concepts

Growth is intrinsically linked to Capacity Planning, which involves forecasting future resource needs based on historical growth trends and anticipated business demands. It directly influences Performance Management by dictating the resources available for workloads and can lead to bottlenecks if unmanaged. Effective growth management relies on Storage Management techniques, such as DFSMS, to automate data placement and lifecycle, and **Workload Management