2.The failing BSDS must be redefined, or alternatively, an existing spare BSDS copy must be renamed.

3.The BSDS is rebuilt from the good copy with an IDCAMS REPRO.

3.6.2 Active Logs

The active log data sets are used for data recovery and to ensure data integrity in case of software or hardware errors. DB2 uses active log data sets to record all updates to user and system data.

The active log data sets are open as long as DB2 is active. Active log data sets are reused when the total active log space is used up, but only after the active log (to be overlaid) has been copied to an archive log.

DB2 supports dual active logs. It is strongly recommended to make use of dual active logs for all DB2 production environments.

Sizing Active Logs

The amount of space dedicated to each individual active log data set is not critical for the DB2 administrator. Traditionally, the active logs have been sized for practical reasons, for example, to make best use of the archive log device (tape cartridge or disk volume).

It is the overall size of all active log data sets that is important for the DB2 DBA: this size plays a critical role in the backup and recovery strategy.

The number of active log data sets, multiplied by the space of each active log, defines an amount of log information most readily available: the capacity of the active log. This capacity defines the time period that has the best recovery performance and the highest data availability service level. The reason is that the DB2 RECOVER utility generally performs better with an active log than with an archive log. See 10.5.2, “Active Log Size” on page 117 for more details.

Impact of Log Size on Backup and Recovery Strategy

The relationship between the different types of log data sets is shown in Figure 5 on page 19. This figure shows a timeline that begins when a DB2 subsystem is first started (Start Time) and proceeds until the current time (Current Time). During this whole time, log data has been generated; this is shown by the DB2 LOG bar.

The log data sets have limited capacity and cannot cover the total time period.

The amount of DB2 log in the active log data sets (the active log capacity) is shown as the time period from Time 2 to the Current Time. The oldest still available archive log corresponds to Time 1. Because the whole log is not available, recoveries are only possible throughout the period from Time 1 to Current Time. The time period from Time 2 to Current Time corresponds to the period with most efficient recoveries because, generally, the active log is allocated on faster devices. The archive log usually overlaps with the active log for a minimum of the last pair of active log data sets not yet archived up to some time after Time 2 and before Current Time. If the data needed for RECOVER or RESTART has been archived, but is still available on an active log data set not yet reused, DB2 accesses the active log.

A good backup and recovery strategy considers:

18Storage Management with DB2 for OS/390

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IBM 5655-DB2, 5695-DF1 manual Sizing Active Logs, Impact of Log Size on Backup and Recovery Strategy
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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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