Cloud service can be treated like a control system, which takes input and produces output.
Control system has two characteristics: Controllability and Observability
Control system is a tested by applying an impulse to it and observe the response of the system.
From this we get the inspiration of cloud server testing:
1. Increase observability: create observation points and record their values. Performance counters, Instrumentation, etc are the tools for this. This can be used for monitoring, but also to observe the internal state of the service for debugging and trouble-shooting.
2. Apply different level of impulse input to observe the output of the system, and the observable states of the system.
3. Find the break point of the system and the corresponding impulse input.