Abstract:
Large-scale data centers involve a set of server racks for storage and computations
for which they require huge amount of power along with some cooling
arrangement. It is observed in the literature that the size of internet data center has
increased 10 times in the last 10 years and energy cost is going up in a similar way. So
there is a need of proper power management in internet data centres so that the power
consumption can be reduced. In this thesis, our focus is modelling and simulation
of internet data centers and comparing two different control techniques at different
workloads on the servers. The first technique is a CRACs ON-OFF method where the
power of computer room air conditioning (CRACs) is automatically controlled on the
basis of servers output temperature. In particular, if the temperature of a server rack in
internet data centre is greater than some fixed temperature, the CRACs are turned on,
otherwise the CRACs will stay off. The second method is the multi-steps ON/OFF
control in which the CRACs are partially turned on and off on the basis of outer air
temperature of servers. We vary the intermediate steps to 1 and 3 in the multi-step
ON/OFF control. It is observed that the two different control techniques can ensure
a desired output temperature of server racks, but CRACs ON-OFF control method
involves more and sharp power peaks which can cause problems in the operation of
IDCs. The multi-step CRAC’s ON/OFF control involve small power peaks and therefore
can be considered a better option as compared to CRACs ON-OFF method. The
behaviour of the control system is almost similar under different workload conditions.
The proposed multi-step CRAC’s ON/OFF control is an important contribution of
this thesis which can minimize the total power consumption of the data center. An
important future work will be to consider state estimation in the modelling and control
strategy under different workloads.
