* find problem;
* identify root cause of the problem;
* write automated, semi-automated or manual test case, which will highlight problem;
* fix problem.
If you will not use test cases at development and staging stages, then you will just use your production environment for testing purposes. If your downtime cost you nothing - don't bother with test cases.
In our case, we had similar problem, so I created very simple test case in shell in less than 2 hours. We spent more than year until it was fully fixed.
In our case, we had similar problem, so I created very simple test case in shell in less than 2 hours. We spent more than year until it was fully fixed.