IEHMOVE

Enhanced Definition

`IEHMOVE` is an IBM mainframe utility program used primarily for moving or copying datasets between volumes or within the same volume on z/OS systems. It supports various dataset organizations, including sequential datasets and Partitioned Datasets (PDS), and has limited support for VSAM datasets. While still available, it is largely considered a legacy utility, with `ADRDSSU` (DFSMSdss) being its more powerful and commonly used successor.

Key Characteristics

- Dataset Operations: Primarily performs move and copy operations for sequential datasets and PDSs, including members within PDSs.
- Legacy Utility: One of the older IBM utilities for dataset management, often superseded by more advanced tools like ADRDSSU for modern z/OS environments.
- JCL Invocation: Executed via Job Control Language (JCL), requiring EXEC PGM=IEHMOVE and specific control statements to define the source, destination, and type of operation.
- Device Support: Can move/copy datasets between different types of DASD (Direct Access Storage Device) volumes and to/from tape devices.
- Limited VSAM Support: While it can handle some VSAM operations, its capabilities are significantly less robust than dedicated VSAM utilities or ADRDSSU.
- Control Statements: Uses a specific set of control statements (e.g., MOVE, COPY, DSNAME, VOL) to specify the datasets and volumes involved in the operation.

Use Cases

- Migrating Datasets: Moving individual sequential datasets or PDSs from one DASD volume to another, perhaps to balance storage utilization or consolidate data.
- Copying Libraries: Creating a backup copy of a Partitioned Dataset (PDS) library, such as a JCL library or a COBOL source library, to a different volume or dataset.
- Renaming Datasets: Effectively renaming a dataset by copying it to a new name and then deleting the original, although dedicated rename utilities or JCL can often achieve this more directly.
- Archiving Data: Moving infrequently accessed sequential datasets from high-performance DASD to tape for long-term storage and cost savings.
- Consolidating Space: Moving datasets off a nearly full volume to a less utilized one to free up space.

Related Concepts

IEHMOVE is invoked through JCL (Job Control Language), where DD statements define the source and target datasets and volumes, and SYSIN provides the utility's control statements. It operates directly on datasets (sequential, PDS, VSAM) and volumes (DASD, tape). In modern z/OS, it is largely replaced by ADRDSSU (DFSMSdss), which offers superior performance, more comprehensive features (e.g., full volume dump/restore, data compression, better VSAM support), and integration with DFSMS storage management policies. Understanding IEHMOVE provides historical context for how dataset management evolved on the mainframe.

Best Practices:

Prefer Modern Utilities: For new development or significant data movement tasks, always consider using ADRDSSU (DFSMSdss) or IDCAMS (for VSAM) as they are more robust, efficient, and feature-rich.
Understand Limitations: Be aware of IEHMOVE's limitations, especially regarding large datasets, complex VSAM structures, and its inability to handle certain advanced dataset attributes.
Test Thoroughly: Before performing critical moves or copies, especially in production, test the IEHMOVE JCL and control statements in a non-production environment.
Verify Return Codes: Always check the return code of the IEHMOVE step in your JCL; a non-zero return code indicates a problem that needs investigation.
Backup Before Moving: For critical data, ensure a backup exists before initiating a MOVE operation, as a failed move could result in data loss.