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Administration Guide

Chapter 23. High Availability in the Windows NT Environment

You can set up your database system so that if a machine fails, the database server on the failed machine can run on another machine. On Windows NT, you implement failover support with Microsoft Cluster Server (MSCS). To use MSCS, you require Windows NT Version 4.0 Enterprise Edition with the MSCS feature installed.

MSCS can perform both failure detection and the restarting of resources in a clustered environment, such as failover support for physical disks and IP addresses. (When the failed machine is online again, resources will not automatically fall back to it, unless you previously configure them to do so. For more information, see "Fallback Considerations".)

Before you enable DB2 instances for failover support, perform the following planning steps:

  1. Decide which disks you want to use for data storage. Each database server should be assigned at least one disk for its own use. The disk that you use to store data must be attached to a shared disk subsystem, and must be configured as an MSCS disk resource.

  2. Ensure that you have one IP address for each database server that you want to use to support remote requests.

When you set up failover support, it can be for an existing instance, or you can create a new instance when you implement the failover support.

To enable failover support, perform the following steps:

  1. Create an input file for the DB2MSCS utility.

  2. Run the DB2MSCS utility.

  3. If you are using a partitioned database system, register database drive mapping to enable mutual takeover. See "Registering Database Drive Mapping for Mutual Takeover Configurations in a Partitioned Database Environment".

After you finish enabling the instance for failover support, your configuration will resemble Figure 79.

Figure 79. Example MSCS Configuration


The following sections describe the different types of failover support, and how to implement them. Before performing any of the steps described below, you must already have the MSCS software installed on every machine that you want to use in an MSCS cluster. In addition, you must also have DB2 installed on every machine.

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