DB2 & IMS

When IBM’s Information Management System (IMS) was introduced, its capacity exceeded what most customers deemed necessary. Times have changed. Today, a key limitation of IMS is its inability to natively address databases larger than 8GB.
 

You need a database partitioning tool to increase IMS capacity and improve performance. These tools let you partition an extremely large database into small partitions that IMS can support, making a large database look like several small databases, effectively avoiding IMS’ capacity constraints.

To maintain high data availability, you also need to be able to reorganize the database while it’s online, using tools compatible with your partitioning strategy. Each partitioning tool has a companion set of reorganization tools.

Software Partitioning Solutions

Third-party software developers, as well as IBM, offer the tools to address these issues. The effectiveness of these tools depends a great deal on the complexity of your IMS environment. To further complicate matters, the process for implementing some of the solutions is essentially a one-way street, so if you determine it isn’t the right solution for you after implementation, rolling back to a previous state can be difficult.

This article examines factors to consider when selecting a partitioning tool. Depending on your environment and the tool you choose, the disruptions of implementing a partitioning solution can be major or minor. By carefully evaluating your environment and the available tools, you can minimize the implementation efforts.

Evaluate Your IMS Environment

The first step in selecting a partitioning tool is to evaluate your IMS environment. Several factors can affect the suitability of specific partitioning tools:


-        The number of IMS databases you support

-        The use of logical links between the databases

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