Implementing Siebel eBusiness Applications on DB2 UDB for z/OS and OS/390 > Maintenance Considerations for zSeries >

Setting Database Connection Pooling

Siebel 7 introduced Siebel database connection pooling which decreases the necessary number of DB2 DBATs. The use of Siebel database connection pooling may allow Siebel zSeries customers to use the default DSMaxCursorSize=-1 and DSPreFetchSize=-1 with careful DB2 buffer pool tuning and utilizing DB2 storage contraction DSNZPARMs as documented in this guide.

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.

For more information on configuring Database Connection Pooling and Multiplexing, see the Performance Tuning Guide.