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In this paper, we study approximation algorithms for several NP-hard facility location problems. We prove that a simple local search heuristic yields polynomial-time constant-factor approximation bounds for the metric versions of the uncapacitated k-median problem and the uncapacitated facility location problem. (For the k-median problem, our algorithms(More)
—We describe the design of an agile data center with integrated server and storage virtualization technologies. Such data centers form a key building block for new cloud computing architectures. We also show how to leverage this integrated agility for non-disruptive load balancing in data centers across multiple resource layers-servers, switches, and(More)
Consider a hierarchical network in which each node periodically issues a request for an object drawn from a xed set of unit-size objects. Suppose further that the following conditions are satissed: the frequency with which each node accesses each object is known; each node has a cache of known capacity; any cache can be accessed by any node; any request is(More)
—Virtualization technologies like VMware and Xen provide features to specify the minimum and maximum amount of resources that can be allocated to a virtual machine (VM) and a shares based mechanism for the hypervisor to distribute spare resources among contending VMs. However much of the existing work on VM placement and power consolidation in data centers(More)
In a large-scale information system such as a digital library or the web, a set of distributed caches can improve their eeectiveness by coordinating their data placement decisions. Using simulation, we examine three practical cooperative placement algorithms including one that is provably close to optimal, and we compare these algorithms to the optimal(More)
Exponential growth in storage requirements and an increasing number of heterogeneous devices and application policies are making enterprise storage management a nightmare for administrators. Back-of-the-envelope calculations, rules of thumb, and manual correlation of individual device data are too error prone for the day-today administrative tasks of(More)
The designers of clustered file systems, storage resource management software and storage virtualization devices are trying to provide the necessary planning functionality in their products to facilitate the invocation of the appropriate corrective actions in order to satisfy user specified service level objectives (SLOs). However, most existing approaches(More)
The logic blocks (CLBs) of a lookup table (LUT) based FPGA consist of one or more LUTs, possibly of different sizes. In this paper, we focus on technology mapping for CLBs with several <italic>independent</italic> LUTs of two different sizes (called ICLBs). The Actel <italic>ES6500</italic> family is an example of a class of commercially available ICLBs.(More)