Flexible and efficient resource management in a virtual cluster environment

Virtual machine (VM) use in a cluster environment imposes many challenges upon a cluster administrator. As the number of VMs across a site grows, manually tracking transient site state information such as resource availability and VM locations and status while enforcing policies for running large numbers of VMs across a cluster becomes increasingly difficult. In this dissertation I focus on VM use in clusters and consider the management and efficiency problems that arise in this unique environment. I present Usher, a virtual machine management system designed to impose few constraints upon the computing environment under its management. Usher enables administrators to choose how their virtual machine environment will be configured and the policies under which it will be managed. Usher cluster administrators can push basic virtual cluster management tasks such as VM start and stop out to the users (virtual cluster creators) themselves, reducing administrator workload and allowing users to create virtual clusters on demand. The modular design of Usher allows for alternate implementations for authentication, authorization, infrastructure handling, logging, and virtual machine scheduling. The design philosophy of Usher is to provide an interface whereby users and administrators can request virtual machine operations while delegating administrative tasks and policy enforcement for these requests to modular plugins. I present an Usher scheduling plugin designed to map virtual machines onto physical machines such that an arbitrarily defined utility is optimized. I discuss possible cluster scheduling goals and present a representative cluster scheduling problem called Fair Maximum Utilization (FMU). Exploration of scheduling heuristics of varying levels of sophistication applied to FMU suggest that those which make better VM resource demand predictions and only slight schedule adjustments work well in genera

Geometric Integration of the Collisional N-Body Problem

Acknowledgements I would like to thank my advisor, Dr. Ben Leimkuhler, whose bold confidence in my mathematical potential rescued me from the depths of concrete construction and placed me firmly back into the world of academia. I am obliged to Dr. Leimkuhler for his advice, support, ideas, and provision of a stimulating environment in which to complete my mathematics curriculum. I thank Dr. Anne Kvaerno / for her assistance with mathematical issues relevant to this report. In addition, I am indebted to Dr. Kvaerno / for her encouragement and support during the stressful months of report preparation. I am blessed to have a loving and supportive family, and I thank each member. I am most grateful to my beautiful wife Karin for her love, care, and understanding throughout our life together

Access and Mobility of Wireless PDA Users

In this paper, we analyze the mobility patterns of users of wireless handheld PDAs in a campus wireless network using an 11 week trace of wireless network activity. Our study has three goals. First, we characterize the high-level mobility and access patterns of handheld PDA users and compare these characteristics to previous workload mobility studies focused on laptop users. Second, we develop two wireless network topology models for use in wireless mobility studies: an "evolutionary topology model" based on user proximity and a "campus waypoint" model that serves as a trace-based complement to the random waypoint model. Finally, we use our wireless network topology models as a case study to evaluate ad-hoc routing algorithms on the network topologies created by the access and mobility patterns of users of modern wireless PDAs.Pre-2018 CSE ID: CS2004-078

Access and Mobility of Wireless PDA Users

this paper, we describe the trace that we use to perform our study (Section 2), summarize the mobility behavior of our PDA users (Section 3), describe the two new mobility models that we derive from our trace (Section 4), and present initial results of ad-hoc routing simulations using our models and discuss future work (Section 5

Usher: An Extensible Framework for Managing Clusters of Virtual Machines

Usher is a virtual machine management system designed to impose few constraints upon the computing environment under its management. Usher enables administrators to choose how their virtual machine environment will be configured and the policies under which they will be managed. The modular design of Usher allows for alternate implementations for authentication, authorization, infrastructure handling, logging, and virtual machine scheduling. The design philosophy of Usher is to provide an interface whereby users and administrators can request virtual machine operations while delegating administrative tasks for these operations to modular plugins. Usher’s implementation allows for arbitrary action to be taken for nearly any event in the system. Since July 2006, Usher has been used to manage virtual clusters at two locations under very different settings, demonstrating the flexibility of Usher to meet different virtual machine management requirements

To Infinity and Beyond: TimeWarped Network Emulation

The goal of this work is to subject unmodified applications running on commodity operating systems and stock hardware to network speeds orders of magnitude faster than available at any given point in time. This paper describes our approach to time dilation, a technique to uniformly and accurately slow the passage of time from the perspective of an operating system by a specified factor. As a side effect, physical devices— including the network—appear relatively faster to both applications and operating systems. Both qualitative and statistical evaluations indicate our prototype implementation is accurate across several orders of magnitude. We demonstrate time dilation’s utility by conducting highbandwidth head-to-head TCP stack comparisons and application evaluation.