Oracle7 Server Administrator's Guide
Initial Tuning Guidelines
You can make a few significant tuning alterations to Oracle7 immediately following installation. By following these instructions, you can reduce the need to tune Oracle7 when it is running. This section gives recommendations for the following installation issues:
Allocating Rollback Segments
Proper allocation of rollback segments makes for optimal database performance. The size and number of rollback segments required for optimal performance depends on your application. The Oracle7 Server Tuning manual contains some general guidelines for choosing how many rollback segments to allocate based on the number of concurrent transactions on your Oracle7 Server. These guidelines are appropriate for most application mixes.
To create rollback segments, use the CREATE ROLLBACK SEGMENT command.
See Also: For information about the CREATE ROLLBACK SEGMENT command, see the Oracle7 Server SQL Reference.
Choosing Sizes for Rollback Segments
The size of your rollback segment can also affect performance. Rollback segment size is determined by the storage parameters in the CREATE ROLLBACK SEGMENT statement. Your rollback segments must be large enough to hold the rollback entries for your transactions.
See Also: For information about choosing sizes for your rollback segments, see the Oracle7 Server Tuning manual.
Choosing the Number of DB_BLOCK_LRU_ LATCHES
Contention for the LRU latch can impede performance on symmetric multiprocessor (SMP) machines with a large number of CPUs. The LRU latch controls the replacement of buffers in the buffer cache. For SMP systems, Oracle automatically sets the number of LRU latches to be one half the number of CPUs on the system. For non-SMP systems, one LRU latch is sufficient.
You can specify the number of LRU latches on your system with the initialization parameter DB_BLOCK_LRU_LATCHES. This parameter sets the maximum value for the desired number of LRU latches. Each LRU latch will control a set of buffers and Oracle balances allocation of replacement buffers among the sets.
See Also: For more information on LRU latches, see the Oracle7 Server Tuning manual.
Distributing I/O
Proper distribution of I/O can improve database performance dramatically. I/O can be distributed during installation of Oracle7. Distributing I/O during installation can reduce the need to distribute I/O later when Oracle7 is running.
There are several ways to distribute I/O when you install Oracle7:
- separation of tables and indexes
- density of data (rows per data block)
See Also: For information about ways to distribute I/O, see the Oracle7 Server Tuning manual.