DBMEMPERCENT with Tivoli Storage Manager 6.x, 7.x

Answer

For best results our recommendation is one instance - one Tivoli Storage Manager server on one box and to use the default setting for DBMEMPERCENT of "AUTO". In this configuration the DBMEMPERCENT should not need to be adjusted.

However, there are conditions in which the DBMEMPERCENT should be adjusted.

1) Per the Tivoli Storage Manager 6.x Administration Reference manual > Server Options> DBMEMPERCENT - it states:

If applications other than Tivoli Storage Manager server are running on the system, ensure that the value allows adequate memory for the other applications.

To manage the system memory that is used by each server on a system, use the DBMEMPERCENT server option to limit the percentage of system memory that can be used by the database manager of each server. If all servers are equally important, use the same value for each server. If one server is a production server and other servers are test servers, set the value for the production server to a higher value than the test servers.

Notes:

a) The default value for DBMEMPERCENT is "AUTO". This means the database manager sets the percentage automatically to a value of approximately 70 to 80 percent of system RAM.

b) Per DB2 Documentation

http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/topic/com.ibm.db2.luw.admin.config.doc/doc/r0005544.html > Instance_memory - Instance memory configuration parameter:

The default value of instance_memory is AUTOMATIC. The AUTOMATIC setting results in a value being computed at database partition activation. The computed value ranges between 75 percent and 95 percent of the physical RAM on the system - the larger the system, the higher the percentage. For DB2 database products with memory usage restrictions, the computed value is also limited by the maximum allowed by the product license. For database partition servers with multiple logical database partitions, this computed value is divided by the number of logical database partitions.
Starting with Version 9.7 Fix Pack 1 and Version 9.5 Fix Pack 5, the computed value for the AUTOMATIC setting does not enforce a limit on memory allocated across the instance for DB2 database products without memory usage restrictions. For Version 9.7 and Version 9.5 Fix Pack 4 or earlier, the computed value for the AUTOMATIC setting represents a limit for all DB2 database products.