Measure thrice, check twice, cut once

An old adage in carpentry is to Measure Thrice, Check Twice and Cut Once.

In the heat of a performance problem, it is very tempting to try different tuning parameters without fully understanding the root-cause of the problem. Some changes or combination of changes can have a negative impact on the system. After trying many tuning changes, it is possible that some of the non-beneficial changes are not rolled back.

From past experiences, we found that system optimization is often more effective and efficient if the problem is correctly analyzed and the root cause clearly identified. An approach that we have adopted is as follows: