Setting Up Multiple Residency

Multiple residency refers to multiple database server instances and their associated shared memory and disk structures coexisting on a single computer.

Multiple residency is different from multiple versions in that you use the Server Instance Manager to create and manage further database server instances, rather than install additional copies of the database server in different directories on your computer.

Creating multiple independent database server environments on the same computer allows you to:

• Separate production and development environments

  You can protect the production system from the unpredictable nature of the development environment.

• Isolate critically important or sensitive databases

  You can increase security or accommodate more frequent backups than most databases require. When you use multiple residency, each database server has its own configuration file. Thus, you can create a configuration file for each database server that meets its special requirements for backups, shared-memory use, and tuning priorities.

• Test distributed data transactions on a single computer

  If you are developing an application for use on a network, you can use local loopback to perform your distributed-data simulation and testing on a single computer. (See the section on using a local loopback connection in the IBM Informix: Dynamic Server Administrator's Guide.) Later, when a network is ready, you can use the application without changes to application source code.

Planning for Multiple Residency

When you plan for multiple residency on a computer, consider the following factors:

• Storage space

  Each database server must have its own unique storage space. You cannot use the same disk space for more than one instance of a database server. When you prepare an additional database server, you need to repeat some of the planning that you did to install the first database server. For example, you need to consider these questions:

  • Will you use mirroring? Where will the mirrors reside?
  • Where will the message log reside?
  • Can you dedicate a tape drive to this database server for its logical logs?
  • What kind of backups will you perform?
• Memory

  Each database server has its own memory. Can your computer handle the memory usage that an additional database server requires?

Creating a New Database Server Instance

Before you set up multiple residency, you must install one database server as described in Installing Dynamic Server. It is not necessary to install more than one copy of the database server binary files. All instances of the same version of the database server on one computer can share the same executable files.

To set up multiple residency, use the Server Instance Manager. To use the Server Instance Manager program, you must have administrative privileges on the database server. However, local administrator privileges are sufficient, even if the database server was installed for domain use.

Before you use the Server Instance Manager, verify that you are a member of the Informix-Admin group For more information, see Verifying Administrators Group Membership.

After you enter the required information, the Server Instance Manager installs services, records environment variables, updates the registry, and creates an onconfig file for the new database server instance.