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Implementing Siebel eBusiness Applications on DB2 UDB for OS/390 and z/OS > Preparing for Implementation on the DB2 Host >

Setting Database Connection Pooling

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The IBM DB2 Connect connection concentrator feature (also known as transaction pooling) is not recommended for Siebel 7, because Siebel performance and scalability tests demonstrate no benefits from this feature. The Siebel application provides a similar feature, Siebel DB Connection Pooling, that meets all Siebel performance and scalability requirements on all database platforms. Siebel DB Connection pooling is optimized for Siebel applications.

Siebel Object Manager server components offer the ability to share and reuse database connections, a feature that is referred to as Siebel Database Connection Pooling and Multiplexing. This feature saves the overhead of creating new database connections for each user session and allows the number of concurrent user sessions to exceed the number of database connections.

When you enable Siebel Database Connection Pooling and Multiplexing, the Object Manager component maintains a pool of database connections. When a new connection is needed (a user session is started), the Object Manager looks for an unused connection in the pool. If no connections are available and the pool has less than the maximum number (MaxSharedDbConns) of connections, then a new connection is created. When the maximum number of connections is reached, the Object Manager assigns the session to an existing connection and multiplexes the database operations from sessions sharing the connection. When the number of concurrent sessions requires sharing connections, the Object Manager attempts to share the connections equitably. As sessions terminate, the Object Manager keeps track of connection utilization and attempts to maintain the minimum number (MinSharedDbConns) of connections in the pool. If there are unused connections, they are released until there are only the minimum number.

Three parameters control Siebel Database Connection Pooling and Multiplexing:

MinSharedDbConns. Minimum number of shared database connections used for general purpose operations.
MaxSharedDbConns. Maximum number of shared database connections used for general purpose operations.
MinTrxDbConns. Minimum number of dedicated database connections used for special purposes.

Set these parameters to the expected maximum number of concurrent users divided by ten (10). This assumes a 30-second think time between operations. You should adjust the ratio in proportion to the actual think time for your particular implementation; for example, if you expect a maximum of 1000 concurrent users, you should set the parameters to 100.

To disable Database Connection Pooling and Multiplexing, set all three parameters to -1. When Database Connection Pooling and Multiplexing is disabled, each user creates a database connection at session creation and releases it at session termination.

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