Multiple databases on an Amazon RDS for Db2 DB instance

You can create multiple databases on a single RDS for Db2 DB instance by calling the rdsadmin.create_database stored procedure. A single RDS for Db2 DB instance is limited to 50 databases. This number includes databases in both activated and deactivated states.

By default, Amazon RDS activates databases when you create them. To optimize memory resources, you can deactivate databases that you use infrequently and then activate them later when needed. For more information, see Deactivating a database and Activating a database.

The number of activated databases on a DB instance depends on the available memory resources on the server. Memory resources differ based on the DB instance class and the amount of memory configured for the database. For information about DB instance classes, see DB instance classes. For information about how to update the memory for an RDS for Db2 database, see rdsadmin.update_db_param.

We recommend that you choose a DB instance class that has 2 GB of memory for common database tasks, operating system requirements, and other Amazon RDS automation tasks such as backups. For more information about changing the DB instance class, see Modifying an Amazon RDS DB instance.

In addition, IBM recommends a minimum of 1 GB of memory for each active database. For more information, see Disk and memory requirements in the IBM documentation.

You can calculate the maximum number of active databases a DB instance can have with the following formula:

Active database limit = (total server memory - 2 GB) / 1 GB 

The following example shows the maximum number of active databases for a DB instance with a db.m6i.xlarge DB instance class:

Active database limit = (total server memory - 2 GB) / 1 GB 
                      = (16 GB - 2 GB) / 1 GB 
                      = 14 databases

When Amazon RDS recovers a database after a crash, it activates the database if it was previously active. In certain cases, such as when you modify a DB instance class to a lower memory configuration, there might be insufficient memory to activate all databases on the DB instance. In those cases, Amazon RDS activates databases in the order in which they were created.