Implementing Siebel eBusiness Applications on DB2 UDB for z/OS and OS/390 > Migrating Data Using Siebel EIM > Setting Up EIM for DB2 >

Optimizing DB2 Database Logging

The number of parallel streams that the DB2 UDB for z/OS and OS/390 environment can support is often limited more by the DB2 logging throughput rate than anything else. The commit process waits for a successful write to the active log and, if there is contention on the logs, performance suffers. Possible solutions to ease bottlenecks caused by logging performance include:

• Increase the number of output buffers for writing active log datasets. The size of the output buffer can be changed in DSNZPARM OUTBUFF.
• Increase the active log size. If logs fill up faster than they can be archived, performance suffers.
• Determine the optimal number of DB2 active logs based on peak EIM loads plus a cushion.
• Place the active log data sets on separate dedicated volumes.
• Place archive logs on a virtual tape system (VTS), or disk if VTS is not available.
• Define all table spaces (base tables and interface tables) with compression, which reduces logging, and decreases I/O.
• Consider data sharing when a single subsystem cannot handle the logging tasks.