numdb - Maximum number of concurrently active databases including host and System i® databases configuration parameter
This parameter specifies the number of local databases that can be concurrently active, or the maximum number of different database aliases that can be cataloged on a Db2 Connect server.
This parameter is overloaded.
The effect of the numdb database
manager configuration parameter depends on the environment in which
the parameter is used.
- For a Db2 Connect environment, you can specify the maximum number of database aliases that can be cataloged on a Db2 Connect server using the numdb database manager configuration parameter.
- Outside of a Db2 Connect environment, you can specify the number of local databases that can be concurrently active using the numdb database manager configuration parameter.
- Configuration type
- Database manager
- Applies to
-
- Database server with local and remote clients
- Database server with only local clients
- Partitioned database server with local and remote clients
- Parameter type
- Configurable
- Default [range]
-
- UNIX Db2® pureScale® environment
- 32 [1 - 200]
- UNIX Database server with local and remote clients
- 32 [1 - 256 ]
- UNIX Database server with only local clients
- 8 [1 - 256 ]
- Windows Database server with local and remote clients
- 32 [1 - 256 ]
- Windows Database server with only local clients
- 3 [1 - 256 ]
- Unit of measure
- Counter
Usage notes
- It is important to remember when setting or updating this parameter that each database takes up storage, and each active database requires an additional new shared memory segment.
- Set numdb to the default value if the number of databases being run on the instance is less than the default.
- Use of the numdb configuration parameter must be coordinated with the db2_database_cf_memory and cf_db_mem_sz configuration parameters.
- Changing the numdb parameter can impact the total amount of memory allocated. As a result, frequent updates to this parameter are not recommended. Plan the configurations for all parameters that are related to memory allocation for a database or an application connected to that database, and change them all at the same time.
- In addition to the numdb limit in a Db2 pureScale environment, there is a maximum number of database activations across all members in an instance. This maximum number is 512 database activations. As an example, if each member in a four member Db2 pureScale environment activated 200 databases, that is a total of 800 database member activations. Since 800 database activations exceeds the maximum upper limit, an error is returned.
- In a multiple database environment, if member crash recovery (MCR) is required, the number of databases that will be recovered in parallel on each member is set by the value of the numdb configuration parameter or the DB2_MCR_RECOVERY_PARALLELISM_CAP registry variable, whichever value is smaller.