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Unformatted text preview: The Cost of a Cloud: Research Problems in Data Center Networks Albert Greenberg, James Hamilton, David A. Maltz, Parveen Patel Microsoft Research, Redmond, WA, USA This article is an editorial note submitted to CCR. It has NOT been peer reviewed. The author takes full responsibility for this articles technical content. Comments can be posted through CCR Online. Abstract The data centers used to create cloud services represent a signifi- cant investment in capital outlay and ongoing costs. Accordingly, we first examine the costs of cloud service data centers today. The cost breakdown reveals the importance of optimizing work com- pleted per dollar invested. Unfortunately, the resources inside the data centers often operate at low utilization due to resource strand- ing and fragmentation. To attack this first problem, we propose (1) increasing network agility, and (2) providing appropriate incentives to shape resource consumption. Second, we note that cloud service providers are building out geo-distributed networks of data centers. Geo-diversity lowers latency to users and increases reliability in the presence of an outage taking out an entire site. However, without appropriate design and management, these geo-diverse data center networks can raise the cost of providing service. Moreover, leverag- ing geo-diversity requires services be designed to benefit from it. To attack this problem, we propose (1) joint optimization of network and data center resources, and (2) new systems and mechanisms for geo-distributing state. Categories and Subject Descriptors: C.2.1 Network Architecture General Terms: Design, Economics Keywords: Cloud-service data centers, costs, network challenges 1. INTRODUCTION In recent years, large investments have been made in mas- sive data centers supporting cloud services, by companies such as eBay, Facebook, Google, Microsoft, and Yahoo!. In this paper, we attempt to demystify the structure of these data centers, and to iden- tify areas of opportunity for R&D impact in data center networks and systems. We start our investigation with the question: Where does the cost go in todays cloud service data centers? To quantify data center costs, we consider a data center hous- ing on the order of 50,000 servers that would be built based on currently well-understood techniques, using good quality, highly available equipment. Table 1 provides a rough guide to associated costs. Costs are amortized, i.e., one time purchases are amortized over reasonable lifetimes, assuming a 5% cost of money. By amor- tizing, we obtain a common cost run rate metric that we can apply to both one time purchases (e.g., for servers) and ongoing expenses (e.g., for power). We discuss each row in detail in Section 2....
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- Spring '11