If you allow DB2 to create the archive log data sets on RVA disks, you can take advantage of the compression capability offered by the device.

Depending on the type of application data DB2 is processing and storing in the log data sets, you could obtain a very good reduction in DASD occupancy with RVA and achieve good recoverability at a reasonable price. This is explained in more detail in DB2 for OS/390 and Data Compression, SG24-5261.

Archive to Disk and Tape

DB2 V5 has introduced the option to archive one copy of the log to disk and the other one to tape. This allows more flexibility than when archiving only to tapes and disk space savings when compared to archiving only to disk.

•In case of unavailability of tape units, you can, in fact, cancel the request for allocation (having previously set the WRITE TO OPER parameter to YES in the Archive Log Installation Panel reported in Figure 21 on page 70) and let DB2 continue with a single archiving.

•Disk space utilization is improved by reducing the number of data sets for the dual copy of active logs to one copy of the archive log data set on disk and one on tape.

10.5.2 Active Log Size

The capacity the system administrator specifies for the active log can affect DB2 performance significantly. If the capacity is too small, DB2 might need to access data in the archive log during rollback, restart, and recovery. Accessing an archive log generally takes longer than accessing an active log. An active log which is too small is shown by a non-zero value in A in Figure 41 on page 118.

Log Sizing Parameters

The following DB2 parameters affect the capacity of the active log. In each case, increasing the value the system administrator specifies for the parameter increases the capacity of the active log. See Section 2 of the DB2 Installation Guide, for more information on updating the active log parameters. The parameters are:

The NUMBER OF LOGS field on the installation panel DSNTIPL (see Figure 40 on page 115) controls the number of active log data sets.

The ARCHIVE LOG FREQ field on the installation panel DSNTIPL (see Figure 40) controls how often active log data sets are copied to the archive log.

The UPDATE RATE on the installation panel DSNTIPL (see Figure 40) is an estimate of how many database changes (inserts, update, and deletes) are expected per hour.

The CHECKPOINT FREQ on the installation panel DSNTIPN specifies the number of log records that DB2 writes between checkpoints.

The DB2 installation CLIST uses UPDATE RATE and ARCHIVE LOG FREQ to calculate the data set size of each active log data set.

Calculating Average Log Record Size

One way to determine how much log volume is needed is to calculate the average size in bytes of log records written. To do this, the DB2 system administrator

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IBM 5695-DF1 manual Active Log Size, Archive to Disk and Tape, Log Sizing Parameters, Calculating Average Log Record Size
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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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