1.4 Performance tuning guidelines

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The following guidelines should help you develop an overall approach to performance tuning.

1.4.1 Initial efforts always pay

This is the basic law that most of the performance benefits usually come from initial efforts. While designing the system try to get the requirements/facts, like disk sizes, disk I/O rates, number of users, transaction and batch processing load on CPU, transaction rates, memory requirements, availability, network bandwidth, backup requirements. If not taken care of, these factors later on generally produce smaller benefits and initially require more effort.

1.4.2 Tune the identified constraints

Identify the primary cause of performance bottleneck. If you try to tune resources that have little or no effect on response time, it can actually make subsequent tuning processes more difficult. If there is any significant improvement potential, it lies in improving the performance of the resources that are major factors in the response time. The best approach is to tune identified constraints.

1.4.3 Change one parameter at a time

Even though you are sure that all the changes are going to be beneficial, do not change more than one performance tuning parameter at a time, otherwise you have no way of evaluating how much each change contributed. Changing one parameter at a time helps you to evaluate whether the change does what you want. Remember, every time you change a parameter to improve one area, you almost always affect at least one other area that you may not have considered.

Tune one level of your system at a time

Tune one level of your system at a time. This helps you to understand how much each area contributed. Consider the below-mentioned areas while tuning processes:

Hardware
Network
Operating system
Application server
Web server
Database manager
Application programs
SQL statements

1.4.4 Consider the entire system

Beyond some limits, software alone cannot help much for further performance improvements. You might need to add more storage, additional CPUs, more memory, or a combination of these.

1.4.5 Hardware upgradation

Upgrading hardware is not an easy job inspite of good budget approvals from the management. You can spend money on additional disk storage only to find that you do not have the processing power or the channels to exploit it. So it is very critical to identify which portion of hardware should be upgraded. Also, upgrading hardware does not always work. Sometimes even additional storage or processing power cannot help much to improve performance.

1.4.6 Follow performance tuning process and proper documentation

Try to follow a proper performance tuning methodology and keep every step documented. Before applying any tuning step one must be ready with the scripts to revert that step. This saves a lot of time, as tuning is an iterative process and the possibility of applying same steps again and again usually remains very high.

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