Update aware replica placement

In recent years, companies such as eBay, Facebook, Google, Microsoft, and Yahoo! have made large investments in massive data centers supporting cloud services. These data centers are becoming the hosting platform for a wide spectrum of composite applications with an increasing trend towards more communication intensive applications. As a result, the bandwidth requirements within and between data centers is rapidly growing, and the efficient management of these networking resources is becoming a key ingredient in the ability to offer cost effective cloud services. Replica placement is a specific aspect of cloud management where the goal is to optimally place the applications and their related data over the available cloud infrastructure. The problem is inherently complex since data is continuously updated, and the cost associated with this update increases with the number of data replica and the network distance between them. We model this problem as a soft-capacitated connected facility location problem, which is NP-Hard in the general case. We present the first deterministic constant approximation algorithm for this problem and show, using extensive simulations and realistic data center and network topology, that our algorithm provides practically good placement decisions.