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Network aware virtual machine and image placement in a cloud

Optimal resource allocation is a key ingredient in the ability of cloud providers to offer agile data centers and cloud computing services at a competitive cost. In this paper we study the problem of placing images and virtual machine instances on physical containers in a way that maximizes the affinity between the images and virtual machine instances created from them. This reduces communication overhead and latency imposed by the on-going communication between the virtual machine instances and their respective images. We model this problem as a novel placement problem that extends the class constrained multiple knapsack problem (CCMK) previously studied in the literature, and present a polynomial time local search algorithm for the case where all the relevant images have the same size. We prove that this algorithm has an approximation ratio of (3 + ∈) and then evaluate its performance in a general setting where images and virtual machine instances are of arbitrary sizes, using production data from a private cloud. The results indicate that our algorithm can obtain significant improvements (up to 20%) compared to the greedy approach, in cases where local image storage or main memory resources are scarce.