Cache Subsystem Device Overview

This report lists the devices known by the subsystem at the beginning of the interval. Each line displays statistics for a specific (functional) volume. The I/O rate, divided into two groups (CACHE HIT and DASD I/O), shows the different types of I/O activity in each group. The *ALL line consolidates values at the subsystem level. The fields to review are, in decreasing order of importance:

•I/O RATE, number of I/O requests per second.

•% READ, percentage of read requests compared to all read plus write requests. When combined with DEVICE ACTIVITY RATE of LCU level DEVICE report, this value enables you get to the WRITE ACTIVITY RATE by:

•(100 - %READ) * DEVICE ACTIVITY RATE / 100

•The write activity rate value is an important factor for performance evaluation in a remote copy environment.

•READ H/R, read hit ratio.

•WRITE H/R, write hit ratio.

•DFW, rate of DFW requests.

•STAGE, rate of any (normal or sequential and read or write) I/O requests with cache miss.

•ASYNC RATE, number of tracks asynchronously destaged from cache to disk as a natural consequence of least recently used cache management algorithms.

•ICL, rate of inhibit cache load requests should be at zero. See 9.3.6, “No Caching—Inhibit Cache Load” on page 92.

11.2.1.2 Direct Access Device Activity Report

This report can be produced at either the LCU level (standard) or the Storage Group level for each LPAR. Both reporting levels should be used. Although the LCU report is relevant with CACHE reports, Storage Group level reporting automatically consolidates information in a global view of I/O activity consistent with the installation organization defined to SMS. With appropriate SMS definitions, such Storage Group level reporting should map the applications point of view.

To get standard LCU reporting, specify:

REPORTS ( DEVICE ( DASD ) )

To get Storage Group reporting, specify in the RMF Monitor III postprocessor:

REPORTS ( DEVICE ( SG ( storage-group-name ) ) )

Figure 50 on page 129 shows the Direct Access Device Activity Report at the Storage Group (SG) level.

The response time of a specific volume in a given LPAR consists of service time and volume thread queuing time. Service time splits into:

•Pending time, which covers the channel subsystem and connections delays to the LCU due to ESCON Director switching, and, in ESCON multiple image facility (EMIF), channel sharing between LPARs

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IBM 5655-DB2, 5695-DF1 manual Cache Subsystem Device Overview, Direct Access Device Activity Report, Reports Device Dasd
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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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