one-to-one redundancy. Its purpose is I/O automatic switching to secondary when unattended outage occurs on primary.

Virtual volume, RAID 5, and RAID 6 have made the concept of dual copy practically obsolete.

9.5.2 Concurrent Copy

Concurrent copy is a function the disk storage server controls in conjunction with DFSMS software. Concurrent copy enables taking backup copies of data while minimally impacting the application data access. Concurrent copy delivers a consistent point-in-time copy of a table space while allowing minimum interruption to data access. Table spaces remain available for processing during almost the entire backup process. They must be switched into read mode for only a short time during concurrent copy initialization.

Initiating a concurrent copy operation allows DFSMSdss to build a map of the data to be copied. To create this map in the case of update I/Os, DFSMSdss needs to obtain serialization on the data while the application I/O is suspended. This process establishes the concurrent copy session (or logical copy); then application access to the data can be resumed, and the copy is available for DFSMSdss DUMP or COPY functions.

With concurrent copy, consistent copies of DB2 data objects can be taken almost instantaneously, thus significantly reducing the length of system outage required for backup. The elapsed time for a backup is reduced from the time taken to physically back up the data to a minimum time to establish the concurrent copy session. Either the database must be quiesced, or the table locked in read-only access for the data to be serialized. More backups can be captured and therefore reduce the length of time taken for forward recovery in the event of a recovery. Figure 26 on page 94 shows the difference between a traditional backup and a concurrent copy backup.

Without Concurrent Copy

APPLICATION PROCESSING

APPLICATION PROCESSING

Backup Window

With Concurrent Copy

APPLICATION PROCESSING

APPLICATION PROCESSING

Figure 26. Schema of a Backup with Concurrent Copy

94Storage Management with DB2 for OS/390

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IBM 5655-DB2, 5695-DF1 manual Schema of a Backup with Concurrent Copy

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.