HCM - Hardware Configuration Manager

Enhanced Definition

HCM (Hardware Configuration Manager) is a z/OS component and a graphical user interface (GUI) tool used to define, manage, and activate hardware configurations for IBM mainframe systems. It allows system programmers to create and modify I/O configurations, including channels, control units, and devices, before they are implemented on the physical hardware.

Key Characteristics

- GUI-based: Provides a user-friendly graphical interface for complex I/O configuration tasks, abstracting the underlying HCD (Hardware Configuration Definition) data.
- HCD Integration: Works in conjunction with HCD, generating and managing the HCD source statements (IOCP input) and the IODF (I/O Definition File).
- Configuration Validation: Performs extensive validation checks on the defined configuration to identify potential errors or inconsistencies before activation, ensuring a valid and operable setup.
- Offline Configuration: Allows configurations to be designed and modified offline, independent of the active system, and then activated at a later time.
- Multiple IODFs: Can manage multiple IODFs, enabling different configurations for various LPARs or system environments.
- Activation Support: Facilitates the activation of new or changed configurations, either dynamically (dynamic I/O activation) or via a system IPL (Initial Program Load).

Use Cases

- Initial System Setup: Defining the complete I/O configuration for a new mainframe system or LPAR, including all attached peripherals like disk subsystems, tape drives, and network adapters.
- Hardware Upgrades/Changes: Adding new hardware components (e.g., new storage arrays, OSA cards) or modifying existing channel paths and control unit definitions.
- Disaster Recovery Planning: Creating and maintaining alternative I/O configurations for disaster recovery sites, ensuring rapid system recovery and consistent device mappings.
- Performance Tuning: Adjusting channel path assignments or device allocations to optimize I/O performance for specific workloads or to balance I/O across available resources.
- Problem Determination: Reviewing existing I/O configurations to understand device connectivity, channel paths, and control unit relationships when troubleshooting I/O-related issues.

Related Concepts

HCM is tightly integrated with HCD (Hardware Configuration Definition), acting as the primary GUI for HCD. It generates the IODF (I/O Definition File), which is the binary representation of the hardware configuration used by z/OS. The IOCP (I/O Configuration Program) processes the HCD source statements to create the IODF, and HCM simplifies this entire process by providing a visual interface and validation capabilities. It also plays a crucial role in Dynamic I/O Activation, allowing configuration changes to be applied without requiring a full system IPL.

Best Practices:

Version Control: Maintain strict version control for IODFs and HCD source files, documenting all changes, their reasons, and the associated change management records.
Regular Backups: Regularly back up IODFs and associated configuration data to prevent data loss and ensure rapid recovery from configuration errors.
Test in Non-Production: Always test new or significantly modified configurations in a non-production LPAR or test environment before deploying to production to minimize risk.
Utilize Dynamic Activation: Leverage dynamic I/O activation whenever possible to minimize system downtime for configuration changes, but understand its scope and limitations.
Comprehensive Documentation: Thoroughly document the purpose and details of each I/O configuration element, including channel paths, control units, and devices, for future reference and troubleshooting.