Oracle7 Administrator's Reference for UNIX
The Importance of Tuning
The Oracle Server is a highly tunable software product. As Oracle for UNIX applications increase in scope and complexity, frequent tuning helps maintain system performance and prevent data bottlenecks.
Though this chapter is written from the perspective of single-processor systems, most performance tuning tips are also valid when using the Oracle parallel options.
Note: The tips discussed in this chapter are proven performance tuning tips used on production Oracle7 databases, implemented by Oracle Consulting. Most of the tips indicate an estimated performance benefit in percentages, if implemented. Tuning tips without performance benefit percentages are incalculable.
Types of Performance Bottlenecks
Memory
Memory contention occurs when processes require more memory than is available. To cope with the shortage, the system pages and swaps processes between memory and disk.
Disk I/O
Disk I/O contention is the result of poor memory management (with subsequent paging and swapping), or poor distribution of tablespaces and files across disks. The I/O load should be spread evenly across all disks.
CPU
The CPU is another system component where processes may contend. Although the UNIX kernel allocates the CPU effectively most of the time, many processes compete for CPU cycles. If your system has more than one CPU (multiprocessor environment), there might be different levels of contention on various CPUs.
Oracle Resources
Contention is also common for Oracle resources, such as locks and latches.