10.4.5 Improving Log Write Performance

In this section we present some considerations on choices to improve log write performance.

LOG OUTPUT BUFFER Size

The OUTPUT BUFFER field of installation panel DSNTIPL lets the system administrator specify the size of the output buffer used for writing active log data sets. This field is shown in Figure 40 on page 115. With DB2 V6, the maximum size of this buffer (OUTBUFF) is 400000 KB. Choose as large a size as the MVS system can support without incurring additional paging. A large buffer size will improve both log read and log write performance. If the DB2 PM statistics report shows a non-zero value for B in Figure 41 on page 118, the log output buffer is too small.

WRITE THRESHOLD

The WRITE THRESHOLD field of installation panel DSNTIPL (see Figure 40 on page 115) indicates the number of contiguous 4KB output buffer pages that are allowed to fill before data is written to the active log data set. The default is 20 buffers, and this is recommended. Never choose a value that is greater than 20% of the number of buffers in the output buffer.

Devices for Log Data Sets

The devices assigned to the active log data sets must be fast. In a transactional environment, the DB2 log may have a very high write I/O rate and will have direct impact on the transaction response time. In general, log data sets can make effective use of the DASD Fast Write feature of IBM's 3990 cache.

Avoid Device Contention

To avoid contention on the disks containing active log data sets, place the data sets so that the following objectives are achieved:

•Define log data set on dedicated volumes

•If dual logging is used, separate the access path for primary and secondary log data sets

•Separate the access path of the primary log data sets from the next log data set pair

Do not place any other data sets on disks containing active log data sets. Place the copy of the bootstrap data set and, if using dual active logging, the copy of the active log data sets, on volumes that are accessible on a path different from that of their primary counterparts. Place sequential sets of active log data sets on different access paths to avoid contention while archiving. To achieve all this, a minimum of three volumes on separate access paths is required for the log data sets. A simple example is illustrated in Figure 39 on page 115.

114Storage Management with DB2 for OS/390

Page 135 Page 137
Page 136
Image 136
IBM 5655-DB2 Improving Log Write Performance, LOG Output Buffer Size, Devices for Log Data Sets, Avoid Device Contention
Page 135 Page 137

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.
Top Page Image Contents