Chapter 9. Disk Environment Overview

This chapter considers the disk architecture from a DB2 point of view. It focuses on concepts and recommendations for their practical implementation, rather than on technical details. In order to facilitate the mutual understanding of some storage terms between DB2 administrators and storage administrators, we highlight them in italics. Several considerations in this chapter could also apply to the new tape server environments, such as the IBM Seascape Virtual Tape Server.

9.1 Evolution of Disk Architecture

We can identify four steps in the evolution of the disk architecture that have progressively separated the concept of volume from the concept of physical device.

9.1.1 3380 and 3390 Volumes

The 3380 and 3390 have been available on the market as physical devices characterized by a one-to-one relationship between a disk drive and a volume. The physical characteristics of these devices also represent a logical view that consists of:

•Track size (track image), the number of bytes per track: 47476 and 56664 bytes of data for 3380 and 3390, respectively

•Capacity in terms of number of tracks or gigabytes

•Device address (device number), which is a thread onto which I/O operations are serialized by the operating system

Although the physical devices 3380 and 3390 will eventually no longer be used, the logical view—with the three characteristics of track size, capacity, and addressing—continues to exist in the new concept of logical volume or logical device.

9.1.2 Arrays

An array is the combination of two or more physical disk storage devices in a single logical device or multiple logical devices. Redundant array of independent disks (RAID) distributes data redundantly across an array of disks. The objective is to achieve continuous data availability in the face of various hard drive failures through the use of disk mirroring, parity data generation and recording, hot sparing, and dynamic reconstruction of data from a failed disk to a spare disk. RAID technology provides the disk I/O system with high availability. RAID types have been categorized into five levels: RAID 1 through 5. Some new definitions have been developed to address new implementations or updated views of the RAID concept.

Each RAID level has some basic characteristics, but all of them have a fixed mapping between logical devices (or logical volumes) and physical drives. Currently admitted definitions (see IBM RAMAC Array Subsystem Introduction, GC26-7004)are:

• RAID 0: data striping without parity

© Copyright IBM Corp. 1999

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IBM 5695-DF1, 5655-DB2 manual Disk Environment Overview, Evolution of Disk Architecture, 1 3380 and 3390 Volumes, Arrays
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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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