Abstract
A cloud federation is a current paradigm that enables partnered cloud providers to share idle capacities during low demand periods and to purchase spare resources during demand spikes. In this research, we propose an optimal overbooking policy to maximize federation members’ profits and enhance cloud users’ experiences. The proposed policy overcomes cloud providers’ low utilization and increases their profits. Under the market-oriented cloud federation system, we use the number of idle resources in the cloud federation and the operational costs of those resources to help the provider decide on its instance exchange price. Under such a price mechanism, we develop an optimal overbooking model and identify the conditions necessary for optimal solutions. Through implementing the optimal mechanism, we observe that the proposed overbooking policy can improve a federated provider’s profits and decrease the probability of service level agreement (SLA) violation. When a provider’s capacity is relatively large and the provider adopts the proposed overbooking policy, it could achieve maximum profits and decline its SLA violation when it has unmet customer demands and there are idle resources in the cloud federation. Through establishing the cooperative game model of the cloud federation, we make a reasonable profit distribution based on Shapley value. The cloud provider’s profits and the probability of the SLA violation change as the instance price, the distribution of unserved customers, the number of federation members and penalty cost change. Compared with the other overbooking policies and no overbooking mechanisms, our research improves profits and reduces cloud provider’s overbooking risks, thereby presenting a win-win situation for both the individual providers and the cloud federation.
Highlights
Driven by the rapid growth in the Internet of things(IoT), real-time big data, and the adoption of service oriented architectures and Web 2.0 applications, the emergence of cloud computing is rapidly gaining momentum as an alternative to traditional IT [1]
Unlike the current overbooking policy, which mainly considers the single service provider’s strategy, through adjusting the exchange price dynamically based on a cloud federation trading mechanism, we propose an optimal overbooking policy to ensure cloud providers exchange resources with cloud federation members
THREE KEY ELEMENTS FOR THE OPTIMAL OVERBOOKING MODEL From the expected profits (2) and the optimal conditions of the overbooking policy (11), we find that the expected profits and optimal overbooking quantities are affected by three key elements: (i) the probability of buying idle resources from the cloud federation; (ii) the probability of selling idle resources; and (iii) the unit exchange price
Summary
Driven by the rapid growth in the Internet of things(IoT), real-time big data, and the adoption of service oriented architectures and Web 2.0 applications, the emergence of cloud computing is rapidly gaining momentum as an alternative to traditional IT [1]. Proposition 1:Joining with a cloud federation to exchange resources is a good overbooking strategy for a cloud provider (e.g., Provider i).For Provider i, it will maximize profits E(πi(o∗i )) if the overbooking quantity o∗i satisfies (11) when there are unserviced customers in Provider i and idle resources in the cloud federation,i.e. Nj − oj ≥ oi − Ni ≥ 0 As SME users often lack exact information regarding their need for cloud services, they tend to overestimate their resource requirements and reserve more capacity as a buffer [15]. (i) Probability of buying idle resources B oi, oj The probability of buying idle resources from the cloud federation is related to the situation when there are unmet demands by the provider and idle resources in the cloud federation This means that the cloud provider can obtain extra resources and improve its service level, which increases profits and reduces SLA violations. When all surplus resources are depleted, further demand cannot be satisfied, and the expected profit decreases owing to increases in penalty costs
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