Archive

Enhanced Definition

In the mainframe context, archiving refers to the process of moving infrequently accessed or historical data from primary online storage (like `DASD`) to more cost-effective, long-term, and often slower retrieval media. The primary purpose is to retain data for regulatory compliance, historical analysis, or disaster recovery, while freeing up expensive online resources.

Key Characteristics

- Long-Term Retention: Data is stored for extended periods, often years or decades, as mandated by legal, regulatory, or business requirements.
- Cost-Effective Storage: Typically utilizes cheaper storage media such as magnetic tapes (physical or virtual tape libraries), optical storage, or cloud object storage accessed via z/OS connectors, significantly reducing DASD costs.
- Infrequent Access: Archived data is not expected to be accessed frequently; retrieval processes are generally slower and often involve batch jobs.
- Data Integrity and Security: Employs techniques like data compression, encryption, and checksums to ensure data integrity and security over its lifecycle.
- Metadata Management: Often includes associated metadata (e.g., date archived, retention period, content description) to facilitate future retrieval and management.

Use Cases

- Regulatory Compliance: Storing historical transaction logs, financial records, and audit trails to meet industry-specific regulations (e.g., Sarbanes-Oxley, GDPR).
- Historical Reporting and Analytics: Retaining aged customer data, sales figures, or operational metrics for long-term business intelligence and trend analysis.
- Application Decommissioning: Archiving all associated data from applications that are no longer in use but whose data must be retained for legal or historical reasons.
- Database Archiving: Moving older, inactive records from active DB2 or IMS databases to an archive system to improve database performance and reduce storage footprint.
- Email and Document Archiving: Storing older emails, reports, and documents generated by mainframe applications for discovery or historical reference.

Related Concepts

Archiving is often managed by systems like IBM DFSMS Hierarchical Storage Manager (DFSMSrmm) or DFSMShsm, which automate the migration of data from DASD to lower-cost tiers like tape. It differs from backup in that backups are primarily for disaster recovery and point-in-time restoration, while archives are for long-term retention and retrieval of specific historical data. Archiving heavily relies on tape libraries (physical or virtual) and JCL for batch processing and data movement, and is critical for adhering to data retention policies and compliance mandates.

Best Practices:

Define Clear Retention Policies: Establish and document specific data retention periods based on legal, regulatory, and business requirements for different data types.
Automate Archiving Processes: Utilize tools like DFSMShsm or third-party solutions to automate the identification, migration, and management of archived data, reducing manual effort and errors.
Verify Data Integrity: Periodically verify the integrity of archived data and the readability of the archive media, especially for long-term archives, to prevent data loss.
Document Retrieval Procedures: Maintain clear, up-to-date documentation on how to locate and retrieve archived data, including JCL examples and contact information for support.
Implement Security Measures: Encrypt sensitive data before archiving and ensure appropriate access controls are in place for archived data to protect against unauthorized access.