  We consider a GI/H/n queueing system. In this system, there are multiple
servers in the queue. The inter-arrival time is general and independent, and
the service time follows hyper-exponential distribution. Instead of stochastic
differential equations, we propose two heavy traffic limits for this system,
which can be easily applied in practical systems. In applications, we show how
to use these heavy traffic limits to design a power efficient cloud computing
environment based on different QoS requirements.
