9.5.6 Sequential Data Striping

Sequential data striping provides the opportunity for significant improvement in sequential processing performance by allowing data to be spread across multiple devices that are accessed concurrently transparently to the applications. With sequential data striping, the data transfer rate may be substantially higher than the individual device is capable of sustaining.

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

Sequential data striping is currently a capability for BSAM and QSAM. Sequential data striping should be considered for the sequential processing component of critical batch jobs, as it may well provide a reduction in elapsed time for those jobs, and it may spread workload onto several paths: it smoothes the intensive sequential I/O activity.

DFSMS 1.5.0 extends striping to the data component of VSAM KSDSs, ESDSs, RRDSs, and VRRDSs (no striping for LDSs yet).

Allocating such VSAM data sets and requesting extended format in the Data Class as striping with sustained data rate in MB/sec in the Storage Class allows striped I/O to the data component. VSAM creates the data component in writing the next control interval to the next stripe in a wraparound way and interspersed among a stripe group. When sequentially reading, VSAM creates and drives as many I/O operations independent of each other as the number of available stripes. Therefore the data aggregate rate for a single data component is determined by multiplying the transfer rate between control unit and CPU by the number of stripes.

Sequential data striping works as described above for sequential processing and when the data is processed for nonshared resources (NSR). Striped I/O does not apply for direct processing. Direct processing reads only one CI at a time, as do local shared resource (LSR) and global shared resource (GSR). Record level sharing (RLS) is also excluded from striped I/O processing. Neither KSDSs with key ranges nor the IMBED attribute qualify for striping.

The maximum number of stripes is 16. If more than one stripe is forced to use the same storage path, I/O processing has to complete before the next I/O is started for another stripe.

When dealing with very large DB2 table spaces to be scanned sequentially, performance can be greately improved by utilizing partitions and query parallelism. In DB2 environments, sequential data striping is today of some interest for log archiving onto disk, or could be considered for some utility work file activity, or to improve performance for some large standard image copies. A more widespread usage can be envisioned (for instance to improve the bandwith on active logs) as soon as striping becomes applicable to VSAM LDS and DB2 introduces its exploitation.

Disk Environment Overview 101

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IBM 5695-DF1, 5655-DB2 manual Sequential Data Striping
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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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