The need to ensure Business Continuity and rapid Disaster Recovery is fundamental for any company relying on IBM i systems for its critical applications. IBM PowerHA SystemMirror for i, combined with the advanced features of IBM storage and the PowerVM infrastructure (HMC and VIOS), offers a robust and flexible solution for data replication and high availability management.

Introduction: The PowerHA Ecosystem on IBM i

IBM PowerHA SystemMirror for i is a clustering solution that enables the creation of high availability environments, minimizing both planned and unplanned downtime. It natively integrates with various replication technologies, but those based on external storage offer particular advantages in terms of performance, granularity, and flexibility, especially in virtualized environments with VIOS.

Key Components and Their Synergy

The strength of the solution lies in the synergistic integration of several components:

1. IBM Storage (e.g., FlashSystem, DS8000): These provide the foundation for replication. Technologies like Metro Mirror (synchronous), Global Mirror (asynchronous), and, crucially for our backup purposes, FlashCopy, are vital. The "versatility" of these storage systems lies in their ability to manage logical volumes (LUNs) independently of the operating system, offering advanced functionalities directly at the hardware level.
2. HMC (Hardware Management Console): This is the central control point for Power servers. It allows for the creation and management of logical partitions (LPARs), VIOS configuration, allocation of physical and virtual resources, and monitoring of the entire system.
3. VIOS (Virtual I/O Server): It acts as an intermediary for I/O resources (disk, network) shared among multiple client LPARs. By using NPIV (N_Port ID Virtualization) for Fibre Channel or vSCSI, VIOS allows IBM i LPARs to access LUNs on external storage transparently. This virtualization is essential for LPAR mobility and for the flexible implementation of replication and FlashCopy strategies.
4. IBM PowerHA SystemMirror for i: The software that orchestrates the cluster, monitors the status of resources (applications, data, IP addresses), manages replication, and automates switchover and failover processes.

This combination allows for the design of resilient architectures where data is replicated between distinct storage units (potentially in different sites), and IBM i LPARs can be activated on the secondary site quickly and in a controlled manner.

Storage-Based Replication: The Heart of Resilience

PowerHA leverages the native replication capabilities of IBM storage systems:

• Metro Mirror (Synchronous Replication): Data is written simultaneously to the primary and secondary storage. It guarantees a Recovery Point Objective (RPO) of zero, as there is no data loss in the event of a failover. Ideal for limited distances (typically within ~300km) due to latency.
• Global Mirror (Asynchronous Replication): Writes occur first on the primary storage and are then replicated, with a minimal delay, to the secondary storage. It allows for very low RPOs (seconds or minutes) and is suitable for greater distances.

PowerHA manages these replication relationships, ensuring that the data on the standby LPAR is consistent and ready for use.

LPAR Configuration and the Power of FlashCopy for 7x24 Backups

To maximize efficiency and minimize the impact on production systems, a typical configuration involves at least two IBM i LPARs:

1. Production LPAR: Runs critical workloads. Its data resides on LUNs replicated by the storage.
2. Backup/HA LPAR (or dedicated Backup LPAR):
• In an HA scenario, this LPAR is the failover target and receives replicated data.
• It can also be used specifically for backups, leveraging FlashCopy technology.

FlashCopy for Uninterrupted Backups:

The FlashCopy feature (or storage-level snapshot) is revolutionary for backup processes on IBM i, especially for environments requiring 7x24 operations. The process is as follows:

1. Instantaneous Copy Creation: At the desired time for the backup, PowerHA (or custom scripts interacting with the storage) sends a command to the storage to create a FlashCopy of the production LPAR's LUNs. This operation is almost instantaneous and has minimal to no impact on the production LPAR.
2. Assignment to the Backup LPAR: The "copied" LUNs (FlashCopy targets) are made accessible (mapped) to the Backup LPAR via VIOS.
3. Backup Execution: On the Backup LPAR, normal backup operations (e.g., via BRMS) proceed using the data on the FlashCopy. The production LPAR continues to operate undisturbed, without suffering the I/O load typical of a backup.
4. Copy Release: Once the backup is complete, the FlashCopy relationship can be terminated, and the target LUNs released or reused for the next cycle.

Advantages:

• Drastically Reduced Backup Windows: The only impact on production is the very brief moment for FlashCopy creation.
• Preservation of 7x24 Service: Applications on the production LPAR do not experience interruptions or significant performance degradation due to backups.
• Data Consistency: FlashCopy ensures a point-in-time consistent copy of the data.
• Flexibility: The Backup LPAR can also be used for other purposes (queries, testing) on the "fresh" copied data, without impacting production.

Ease of Managing Switchovers and Failovers

IBM PowerHA SystemMirror for i excels in simplifying and automating switching processes, both planned (switchover) and unplanned (failover).

• Switchover (Planned): Used for scheduled maintenance on the primary server or to test the DR procedure. PowerHA manages in an orderly fashion:
1. The shutdown of applications on the primary LPAR.
2. The final data synchronization (if necessary) and reversal of the storage replication direction (secondary becomes primary).
3. The activation of resources (IP addresses, IASPs, applications) on the secondary LPAR.
   The entire process is orchestrated and can be initiated with a few commands or via a graphical interface.
• Failover (Unplanned): Triggered automatically (or with minimal manual intervention) in case of an unexpected failure of the primary system. PowerHA detects the malfunction and:
1. Verifies the availability of the secondary site.
2. Activates storage replication (if necessary, based on technology and configuration).
3. Brings resources online on the secondary LPAR, making it the new production LPAR.

The ease of management stems from:

• Automation: Multiple complex steps are automated.
• Cluster Resource Groups (CRGs): Resources (applications, data, IP) are logically grouped, simplifying the management of their movement.
• Continuous Monitoring: PowerHA constantly monitors the cluster's status, ready to intervene.
• Test Procedures: PowerHA facilitates non-disruptive failover tests, which are crucial for ensuring disaster preparedness.

The management interface (accessible via 5250 or more modern GUIs like IBM Navigator for i) provides a clear view of the cluster status and allows switchover/failover operations to be initiated with relative simplicity, reducing the risk of human error.

Advantages of Using BRMS on the Backup LPAR

Using BRMS (Backup, Recovery, and Media Services for i) on the Backup LPAR (where backups are performed from the FlashCopy) offers numerous advantages:

1. Centralized and Automated Backup Management: BRMS allows for the definition of complex backup policies, scheduling of backups, and management of the entire media lifecycle.
2. Reliability and Consistency: BRMS ensures that all necessary objects (libraries, IFS, configuration data, security objects) are included in backups consistently.
3. Simplified Media Management: BRMS tracks tape volumes (physical or virtual), their location, content, and expiration date, simplifying recovery.
4. Detailed Reporting: Provides comprehensive logs and reports on backup and recovery operations, useful for audits and troubleshooting.
5. Facilitated Recovery Planning: BRMS automatically generates the necessary steps for recovery, guiding the operator.
6. Integration with Advanced Technologies: Integrates with tape libraries, Virtual Tape Libraries (VTL), and supports media duplication for off-site storage.
7. Backup from a "Cold" Copy: By performing backups on the Backup LPAR using data from the FlashCopy, BRMS operates on a system that is not under production load, ensuring faster and non-impactful backups.
8. Granular Restores: Even if the backup is full, BRMS facilitates the restoration of individual objects or libraries.

The combination of FlashCopy + Backup LPAR + BRMS represents the state-of-the-art for efficient and non-invasive backup strategies on IBM i.

Conclusion

The IBM i architecture based on PowerHA, advanced external storage, HMC, and VIOS offers a complete and extremely versatile solution for data replication and high availability. The introduction of technologies like FlashCopy revolutionizes backup management, allowing for continuous 7x24 operations without compromise. The ease of managing switchovers and failovers, combined with the benefits of established tools like BRMS on the backup partition, makes this platform a preferred choice for companies requiring maximum resilience and protection for their critical data. The investment in these technologies translates into a significant reduction in risk, greater operational efficiency, and the assurance of being able to continue serving the business even in the face of unforeseen events.