During normal operations GDPS continuously monitors all systems and specifically looks for messages indicating that PPRC volume pairs are being suspended. At the occurrence of a suspend, GDPS immediately freezes the image of the secondary disk configuration, to ensure restartability of the applications in the backup location.

The next step is to analyze the reason for the suspend, because each cause can have different levels fo effect. For instance, if the suspend was caused by a secondary equipment problem, it makes sense not to interrupt primary application processing. However, if the suspend was caused by a primary equipment failure, then GDPS, after having stopped the secondary device updates, will either allow applications to continue or force them to stop. The choice is driven by an installation policy. If the failure is part of a disaster unfolding in the primary location, workload restartability is ensured by freezing the secondary data image. If the primary site applications were stopped, no data loss will ever occur.

Automation taking control at a suspend event is possible because the storage server starts an automation window when a suspend condition is detected. The write operation that forced the condition to surface is not completed until the automation has taken specific action. The automation window is essential in taking control at the right moment and ensuring data consistency in the backup location.

If there is a need to make the switch to the backup facility, GDPS executes all the mechanics of removing the failed site systems from the sysplex, changing the status of the former secondary disk configuration to bring the primary back up, switching the network to the backup location, reconfiguring processor capacity in the surviving site as required to support the fallback mode of operation, and finally restarting the application.

9.5.4.3 Extended Remote Copy

XRC is the asynchronous implementation of remote copy. Copies are also established by disk volume, but there is the concept of session, which relates a number of disk volumes that may be associated with the same application. The remote copies are managed by session, and write sequence consistency is maintained across all disk volumes. Although the data currency at the secondary may lag behind the primary by some seconds or minutes, the consistency of the data is preserved even where data is spread across multiple LCUs or storage servers. Figure 31 on page 100 describes the XRC data flow.

Preservation of the write sequence consistency enables easier recovery of any database management system at the secondary site in the event of the disaster. XRC is implemented through the System Data Mover (SDM) function of DFSMS.

For DB2, the recovery is easier because all volumes are brought to a consistent status, so a DB2 restart can be done. The way to ensure recoverability is to use the ERRORLEVEL=SESSION parameter and to place all DB2 volumes in the same XRC session.

The ability to perform a DB2 restart means that recovery at the secondary site may be as quick as a recovery from a failure on the production system. The only drawback to an asynchronous implementation of remote copy is that the currency of the data may lag behind the primary system. This may result in some transactions having to be manually reentered after recovery at the secondary

Disk Environment Overview

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IBM 5695-DF1, 5655-DB2 manual Extended Remote Copy
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5695-DF1, 5655-DB2 specifications

IBM 5655-DB2 and 5695-DF1 are significant components within the IBM software ecosystem, predominantly focusing on data management and integration solutions. These offerings cater primarily to enterprise environments that require robust database management systems and associated frameworks to maintain and manipulate data efficiently.

IBM 5655-DB2 is a well-known relational database management system (RDBMS) that excels in managing large volumes of structured data. Its architecture is designed to support high availability, scalability, and performance, crucial for businesses operating in today’s data-driven world. Some of its main features include advanced indexing capabilities, support for complex queries, and dynamic workload management. Additionally, it provides strong concurrency controls, which enable multiple users to access and manipulate data simultaneously without compromising data integrity.

One of the key characteristics of DB2 is its support for various data types, including JSON and XML, making it versatile for modern applications that generate data in diverse formats. It also features robust security mechanisms to protect sensitive data, aligning with compliance standards across industries. Integration with analytics tools further allows businesses to derive insights from their data, enhancing decision-making processes.

On the other hand, IBM 5695-DF1, also known as the InfoSphere DataStage, is a powerful data integration tool that facilitates the extraction, transformation, and loading (ETL) of data from various sources to target systems. It empowers organizations to streamline their data flows, ensuring that clean, consistent information is available for analysis and operational use. Key features of 5695-DF1 include a user-friendly graphical interface that enhances developer productivity and a rich set of connectors for numerous data sources, enabling seamless data integration.

DataStage also supports real-time data integration, allowing businesses to keep their data synchronized across multiple platforms. Its parallel processing capabilities dedicatedly optimize performance, enabling organizations to handle vast datasets efficiently. It incorporates data quality tools that help in validating and cleansing data before it is used for decision-making processes.

Both IBM 5655-DB2 and 5695-DF1 are part of a broader strategy to accommodate the evolving landscape of data management. Businesses leverage these technologies to enhance their data architectures, fostering agility and competitive advantage in their respective markets. Their integration capabilities, along with a focus on security and scalability, position them as vital assets in modern enterprise environments. Whether managing critical data within a database or ensuring seamless data flow across systems, these IBM offerings provide a comprehensive approach to handling complex data challenges.
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