Aggregating the Bandwidth of Multiple Network Interfaces to Increase the Performance of Networked Applications

Devices capable of connecting to two or more different networks simultaneously, known as host multihoming, are becoming increasingly common. For example, most laptops are equipped with a least a Local Area Network (LAN) and a Wireless LAN (WLAN) interface, and smartphones can connect to both WLANs and 3G-networks (High-Speed Downlink Packet Access, HSDPA). Being connected to multiple networks simultaneously allows for desirable features like bandwidth aggregation and redundancy. Enabling and making efficient use of multiple network interfaces or links (network interface and link will be used interchangeably throughout this thesis) requires solving several challenges related to deployment, link heterogeneity and dynamic behavior. Even though multihoming has existed for a long time, for example routers must support connecting to different networks, most existing operating systems, network protocols and applications do not take host multihoming into consideration. The default behavior is still to use a single interface for all traffic. Using a single interface is, for example, often insufficient to meet the requirements of popular, bandwidth intensive services like video streaming. In this thesis, we have focused on bandwidth aggregation on host multihomed devices. Even though bandwidth aggregation has been a research field for several years, the related works have failed to consider the challenges present in real world networks properly, or does not apply to scenarios where a device is connected to different heterogeneous networks. In order to solve the deployment challenges and enable the use of multiple links in away that works in a real-world network environment, we have created a platform-independent framework, called MULTI. MULTI was used as the foundation for designing transparent (to the applications) and application-specific bandwidth aggregation techniques. MULTI works in the presence of Network Address Translation (NAT), automatically detects and configures the device based on changes in link state, and notifies the application(s) of any changes. The application-specific bandwidth aggregation technique presented in this thesis was optimised for and evaluated with quailty-adaptive video streaming. The technique was evaluated with different types of streaming in both a controlled network environment and real-world networks. Adding a second link gave a significant increase in both video and playback quality. However, the technique is not limited to video streaming and can be used to improve the performance of several, common application types. In many cases, it is not possible to extend applications directly with multilink support. Working on the network-layer allows for the creation of bandwidth aggregation techniques that are transparent to applications. Transparent, network-layer bandwidth aggregation techniques must support the behavior of the different transport protocol in order to achieve efficient bandwidth aggregation. The transparent bandwidth aggregation techniques introduced in this thesis are targeted at Universal Datagram Protocol (UDP) and Transmission Control Protocol (TCP), the two most common transport protocols in the Internet today

Sixth Goddard Conference on Mass Storage Systems and Technologies Held in Cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems

This document contains copies of those technical papers received in time for publication prior to the Sixth Goddard Conference on Mass Storage Systems and Technologies which is being held in cooperation with the Fifteenth IEEE Symposium on Mass Storage Systems at the University of Maryland-University College Inn and Conference Center March 23-26, 1998. As one of an ongoing series, this Conference continues to provide a forum for discussion of issues relevant to the management of large volumes of data. The Conference encourages all interested organizations to discuss long term mass storage requirements and experiences in fielding solutions. Emphasis is on current and future practical solutions addressing issues in data management, storage systems and media, data acquisition, long term retention of data, and data distribution. This year's discussion topics include architecture, tape optimization, new technology, performance, standards, site reports, vendor solutions. Tutorials will be available on shared file systems, file system backups, data mining, and the dynamics of obsolescence

Gollach : configuration of a cluster based linux virtual server

Includes bibliographical references.This thesis describes the Gollach cluster. The Gollach is an eight machine computing cluster that is aimed at being a general purpose computing resource for research purposes. This includes image processing and simulations. The main quest in this project is to create a cluster server that gives increased computational power and a unified system image (at several levels) without requiring the users to learn specialised tricks. At the same time the cluster must not be tasking to administer

Balancing Interactive Performance and Budgeted Resources in Mobile Computing.

In this dissertation, we explore the various limited resources involved in mobile applications --- battery energy, cellular data usage, and, critically, user attention --- and we devise principled methods for managing the tradeoffs involved in creating a good user experience. Building quality mobile applications requires developers to understand complex interactions between network usage, performance, and resource consumption. Because of this difficulty, developers commonly choose simple but suboptimal approaches that strictly prioritize performance or resource conservation. These extremes are symptoms of a lack of system-provided abstractions for managing the complexity inherent in managing performance/resource tradeoffs. By providing abstractions that help applications manage these tradeoffs, mobile systems can significantly improve user-visible performance without exhausting resource budgets. This dissertation explores three such abstractions in detail. We first present Intentional Networking, a system that provides synchronization primitives and intelligent scheduling for multi-network traffic. Next, we present Informed Mobile Prefetching, a system that helps applications decide when to prefetch data and how aggressively to spend limited battery energy and cellular data resources toward that end. Finally, we present Meatballs, a library that helps applications consider the cloudy nature of predictions when making decisions, selectively employing redundancy to mitigate uncertainty and provide more reliable performance. Overall, experiments show that these abstractions can significantly reduce interactive delay without overspending the available energy and data resources.PHDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/108956/1/brettdh_1.pd

Quality of Service based Retrieval Strategy for Distributed Video on Demand on Multiple Servers

The recent advances and development of inexpensive computers and high speed networking technology have enabled the Video on Demand (VoD) application to connect to shared-computing servers, replacing the traditional computing environments where each application was having its own dedicated computing hardware. The VoD application enables the viewer to select, from a list of video files, his favorite video file and watch its reproduction at will. Early video on demand applications were based on single video server where video streams are initiated from a single server, then with the increase in the number of the clients who became interested in VoD services, the focus became on Distributed VoD architectures (DVoD) where the context of distribution may be distributed system components, distributed streaming servers, distributed media content etc.The VoD server must handle several issues in order to be able to present a successful service. It has to receive the clients’ requests and analyze them, calculate the necessary resources for each request, and decide whether a request can be admitted or not. Once the request is admitted, the server must schedule the request, retrieve the required video data and send the video data in a timely manner so that the client does not suffer data starvation in his buffer during the video reproduction. So, the overall objective of a VoD service provider is to provide a better Quality of Service (QoS). Some issues related to QoS are-efficient use of bandwidth, providing better throughput etc.One of the important issues is to retrieve the video data from the servers in minimum time and to start the playback of the video at client side with a minimum waiting time. The overall time elapsed in retrieving the video data and starting the playback is known as access time. The thesis presents an efficient retrieval strategy for a distributed VoD environment where the basic objective is to minimize the access time by maintaining the presentation continuity at the client side. We have neglected some of the network parameters which may affect the access time, by assuming a high speed network between the servers and the client. The performance of the strategy has been analyzed and is compared with the referred PAR (Play After Retrieval) strategy. Further, the strategy is also analyzed under availability condition which is a more realistic approach

Load balancing techniques for I/O intensive tasks on heterogeneous clusters

Load balancing schemes in a cluster system play a critically important role in developing highperformance cluster computing platform. Existing load balancing approaches are concerned with the effective usage of CPU and memory resources. I/O-intensive tasks running on a heterogeneous cluster need a highly effective usage of global I/O resources, previous CPU-or memory-centric load balancing schemes suffer significant performance drop under I/O- intensive workload due to the imbalance of I/O load. To solve this problem, Zhang et al. developed two I/O-aware load-balancing schemes, which consider system heterogeneity and migrate more I/O-intensive tasks from a node with high I/O utilization to those with low I/O utilization. If the workload is memory-intensive in nature, the new method applies a memory-based load balancing policy to assign the tasks. Likewise, when the workload becomes CPU-intensive, their scheme leverages a CPU-based policy as an efficient means to balance the system load. In doing so, the proposed approach maintains the same level of performance as the existing schemes when I/O load is low or well balanced. Results from a trace-driven simulation study show that, when a workload is I/O-intensive, the proposed schemes improve the performance with respect to mean slowdown over the existing schemes by up to a factor of 8. In addition, the slowdowns of almost all the policies increase consistently with the system heterogeneity

The Third NASA Goddard Conference on Mass Storage Systems and Technologies

This report contains copies of nearly all of the technical papers and viewgraphs presented at the Goddard Conference on Mass Storage Systems and Technologies held in October 1993. The conference served as an informational exchange forum for topics primarily relating to the ingestion and management of massive amounts of data and the attendant problems involved. Discussion topics include the necessary use of computers in the solution of today's infinitely complex problems, the need for greatly increased storage densities in both optical and magnetic recording media, currently popular storage media and magnetic media storage risk factors, data archiving standards including a talk on the current status of the IEEE Storage Systems Reference Model (RM). Additional topics addressed System performance, data storage system concepts, communications technologies, data distribution systems, data compression, and error detection and correction

Goddard Conference on Mass Storage Systems and Technologies, volume 2

Papers and viewgraphs from the conference are presented. Discussion topics include the IEEE Mass Storage System Reference Model, data archiving standards, high-performance storage devices, magnetic and magneto-optic storage systems, magnetic and optical recording technologies, high-performance helical scan recording systems, and low end helical scan tape drives. Additional discussion topics addressed the evolution of the identifiable unit for processing (file, granule, data set, or some similar object) as data ingestion rates increase dramatically, and the present state of the art in mass storage technology