allows them a longer stay in cache. Other data sets should be set in may cache Storage Classes, defined with intermediate response time values.

9.4 Paths and Bandwidth Evolution

A path is a logical concept that lies on the physical web of links (cables) existing between hosts and storage servers. This topology can be highly diversified and complex. An important factor of this interface layer is the potential number of parallel activities a specific DB2 subsystem on a specific host can sustain with a given storage server: this is the number of paths.

For any host-LCU association, paths are defined in the IOCP:

•CHPID PATH defines the set of host physical links or channels to be used.

•CNTLUNIT CUNUMBR...PATH enumerates, for each LCU the usable paths from previous set (please note that the name is not related to the SSID).

Similarly, CESTPATH establishes paths between a pair of LCUs for peer-to-peer remote copy (PPRC) by defining the physical links to be used.

The bandwidth between two nodes in the network, such as the host and the LCU, is the maximum number of MB/sec that can instantaneously flow from one node to another. The actual bandwidth represents the possible sustained transfer activity. At building time, Storage Groups should be designed with pathing considerations to control the potential parallel access they offer to allocations, specifically when several control units are merged in a large disk storage server.

Sequential data striping exploits this parallel topology. Sequential data striping is provided as a capability of DFSMS/MVS and it is available only for DFSMS-managed data sets.

The OS/390 Fiber Connection (FICON) Architecture improves from 17 half-duplex to 100 full-duplex MB/sec bandwidth on a physical link. While the number of CHPIDs per channel is still 256 per processor, likewise the number of device addresses per LCU also remains at 256, there is a 16-fold increase (from 16 to 256) in the number of LCUs a physical link can address (and thus in device addresses, or device numbers). A statement of direction exists for S/390 FICON control units. Disk storage servers with native FICON attachments are not yet on the market, but FICON links can already attach to ESCON Directors and split into up to eight 17 MB/sec ESCON physical links to reach unmodified current disk storage servers. So path parallel capabilities should dramatically improve in the next several years.

9.5 Capabilities

Most disk storage server capabilities deal with availability, performance, or sparing space resource. This section reviews the most popular capabilities from a DB2 utilization point of view.

9.5.1 Dual Copy

Dual copy of a volume (called primary volume) is an availability option that triggers duplication of any write onto a shadow volume (secondary volume) of the same physical control unit. It is also referred as RAID 1 because there is a

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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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