Explode
In the context of mainframe systems, "exploding" refers to the process of decompressing or expanding data that was previously compressed. This operation restores the data to its original, uncompressed format and size, making it accessible for applications, utilities, or users that require the full data representation.
Key Characteristics
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- Inverse of Compression: It is the complementary operation to data compression, reversing the process to retrieve the original data.
- Utility-Driven: On z/OS, exploding data is typically performed by specialized utility programs (e.g.,
DFSORT,DFDSS, database utilities likeDB2 RECOVERorIMSutilities) or application-specific routines that understand the compression algorithm used. - Increased Storage Footprint: The exploded data will occupy significantly more storage space (DASD or tape) than its compressed counterpart, often returning to its original size.
- CPU Intensive: The decompression process consumes CPU cycles, which can be a significant consideration for large datasets or high-volume operations.
- Data Integrity: The explosion process must accurately reconstruct the original data without loss or corruption, ensuring the integrity of the information.
Use Cases
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- Data Restoration: Decompressing backup copies of datasets (e.g., VSAM files, sequential files, database images) that were stored in a compressed format to save space.
- Application Processing: Expanding data that was archived or stored compressed to allow applications that do not natively support compressed input to process it.
- Reporting and Analysis: Decompressing log files, transaction records, or historical data for detailed reporting, auditing, or debugging purposes.
- Data Migration: Exploding data before migrating it to a different system or platform that may not support the original mainframe compression format.
Related Concepts
"Explode" is fundamentally linked to data compression, being its necessary inverse operation. Data is often compressed for storage management efficiency, reducing the footprint on DASD or tape and potentially improving I/O performance by transferring less data. Utilities like DFDSS (Data Facility Data Set Services) or DFSORT can perform both compression and explosion, often using specific hardware compression features or software algorithms. Database systems like DB2 and IMS also utilize compression for tablespaces or segments, requiring their own utilities to explode data during recovery or unload processes.
- Plan for Storage: Always ensure sufficient target storage space is available for the exploded data, as it will be significantly larger than the compressed source.
- Monitor CPU Usage: For large-scale explosion operations, monitor CPU consumption, especially during peak hours, to avoid impacting other critical workloads.
- Verify Data Integrity: After exploding, consider using checksums or other validation methods if available to ensure the data was restored correctly and completely.
- Choose the Right Utility: Use the appropriate IBM utility or application-specific tool that matches the original compression method to guarantee successful and efficient decompression.
- Document Compression Methods: Clearly document the compression algorithm and utility used for any compressed data to ensure proper explosion can be performed later.