A content delivery network (CDN) typically consists of geographically-distributed data centers, each containing servers that cache and deliver web contents close to end-users for localized content access purpose. In recent years, optimization of CDN data center energy consumption has attracted increasing research efforts. The key technical challenge is the tradeoff between CDN energy consumption and the content service capability at both the server and the network sides. In this article, we introduce a data center management scheme that effectively reduces the energy consumption of cross-domain CDNs through dynamically provisioning servers and coordinating content delivery operations with respect to dynamic server and network load. The proposed scheme focuses on optimizing the energy-performance tradeoff in two aspects. On one hand, servers in CDN data centers are put to the sleep mode during off-peak hours to save energy. On the other hand, CDN Quality-of-Service (QoS) performance is assured through honoring constraints on servers and network link loads, especially through restricting inter-domain content traffic volume. As a result, the proposed scheme is able to reduce CDN data center energy consumption without compromising its end-to-end QoS performance. According to our experiments based on realistic CDN scenarios, the proposed scheme is able to reduce data center energy consumption by up to 45.9% while achieving desired QoS performance.
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