Memory Tuning

After the CPU, memory is the next most important thing to tune. The primary consumer of memory in an Oracle Internet Directory installation is the Oracle9i database. Make the SGA of the back-end database large enough while leaving room for Oracle Internet Directory and Oracle processes to operate their private stacks and heaps. This section provides some details on determining various components of the SGA.

This section contains these topics:

• Tuning the System Global Area (SGA) for Oracle9i Database Server

• Other Alternatives for a Memory-Constrained System

Tuning the System Global Area (SGA) for Oracle9i Database Server

The SGA should be sized based on the available physical memory on the system running Oracle9i Database Server.

See Also: Oracle9i Database Performance Tuning Guide in the Oracle Database Documentation Library for more information on determining appropriate sizes for the SGA. This book tells how to ensure that the SGA size does not cause increased paging swapping activity. The latter is very detrimental to performance.

Once the available size of the SGA is determined, two primary tuning items need to be considered:

• Size of the shared pool

• Size of the buffer cache

An initial estimate for the shared pool size is .5 MB for each concurrent database connection previously determined.

If this estimate consumes more than 30 percent of the total SGA, use 30 percent of the total SGA instead.

Divide 60 percent of the remaining available SGA size by the block size for the database and use this value for the number of DB_BLOCK_BUFFERS. Both of these values should be initial estimates and can be refined using BSTAT/ESTAT and other RDBMS monitoring tools to determine more accurate sizes for best performance.

Other Alternatives for a Memory-Constrained System

If there is insufficient memory to run both the database and the Oracle directory server on the same computer, then one can put the database on a different computer.