Service-Level Expectations
What level of performance should I expect?
Before your cloud provider can answer this question, you should be prepared to demonstrate the level of performance in your current cloud or on-premise solution. Whether the performance you experience is optimal or not, this allows cloud providers to understand what is (or isn't) performing, and what level of horsepower is required to achieve the needed performance. If this is a new implementation, use your legacy solution as a baseline and add an estimate for transaction growth as a buffer.
Cloud sizing should be approached with facts, as it's easy to oversize or undersize an environment. Over-sizing an environment results in you paying for more than you need and under-sizing results in you not receiving the needed performance. Some of the metrics that should be presented to a potential cloud provider include CPU utilization, memory utilization, input/output operations per second (IOPS) and data growth. Ideally, you would provide this information on each server you are planning to launch in the cloud. If your environment's performance is affected by seasonal peaks, talk to the cloud provider about these specifics.