Fog Computing May Help to Save Energy in Cloud Computing

TLDR

Tiny end‑user computers, called nano data centers, are increasingly used as local servers for IoT and Fog services, yet their energy consumption has not been thoroughly studied. The study aims to analyze the energy consumption of nano data centers by proposing flow‑based and time‑based models for shared and unshared network equipment. The authors validate these models through measurements and experiments comparing the energy usage of services on nano data centers versus centralized data centers. The results show that nano data centers can consume less energy than centralized data centers when the access network type, server utilization, application type, download and update frequency, and preloaded data volume are favorable, while the number of hops has little effect; thus, Fog computing can complement centralized DCs for IoT applications that can be off‑loaded to nDCs, leading to energy savings.

Abstract

Tiny computers located in end-user premises are becoming popular as local servers for Internet of Things (IoT) and Fog computing services. These highly distributed servers that can host and distribute content and applications in a peer-to-peer (P2P) fashion are known as nano data centers (nDCs). Despite the growing popularity of nano servers, their energy consumption is not well-investigated. To study energy consumption of nDCs, we propose and use flow-based and time-based energy consumption models for shared and unshared network equipment, respectively. To apply and validate these models, a set of measurements and experiments are performed to compare energy consumption of a service provided by nDCs and centralized data centers (DCs). A number of findings emerge from our study, including the factors in the system design that allow nDCs to consume less energy than its centralized counterpart. These include the type of access network attached to nano servers and nano server's time utilization (the ratio of the idle time to active time). Additionally, the type of applications running on nDCs and factors such as number of downloads, number of updates, and amount of preloaded copies of data influence the energy cost. Our results reveal that number of hops between a user and content has little impact on the total energy consumption compared to the above-mentioned factors. We show that nano servers in Fog computing can complement centralized DCs to serve certain applications, mostly IoT applications for which the source of data is in end-user premises, and lead to energy saving if the applications (or a part of them) are off-loadable from centralized DCs and run on nDCs.