12 research outputs found
Design Considerations for Integrated Proxy Servers
No full textProxy servers reduce client access times as well as load on servers and networks by caching frequently accessed web objects. In this paper, we argue that the growing heterogeneity of data stored on web servers coupled with the increasing diversity in application requirements have made existing proxy servers inadequate. We examine the architecture and mechanisms required by integrated proxy servers that address this heterogeneity in application requirements and data characteristics. Finally, we briefly describe the architecture of an integrated proxy server that is currently being built in our research lab. 1 Introduction The growth of the Internet and the World Wide Web has enabled an increasing number of users to access vast amounts of information stored at geographically distributed sites. Due to the non-uniformity of information access, however, popular objects create "hot-spots" of server and network load, and thereby significantly increase latency for information access [17]. Pro..
Maximizing efficiency by trading storage for computation
No full textTraditionally, computing has meant calculating results and then storing those results for later use. Unfortu-nately, committing large volumes of rarely used data to storage wastes space and energy, making it a very expen-sive strategy. Cloud computing, with its readily available and flexibly allocatable computing resources, suggests an alternative: storing the provenance data, and means to recomputing results as needed. While computation and storage are equivalent, finding the balance between the two that maximizes efficiency is difficult. One of the fundamental challenges of this is-sue is rooted in the knowledge gap separating the users and the cloud administrators—neither has a completely informed view. Users have a semantic understanding of their data, while administrators have an understanding of the cloud’s underlying structure. We detail the user knowledge and system knowledge needed to construct a comprehensive cost model for analyzing the trade-off between storing a result and regenerating a result, allow-ing users and administrators to make an informed cost-benefit analysis.
An Observation-based Approach Towards Self-managing Web Servers
No full textAs more business applications have become web enabled, the web server architecture has evolved to provide performance isolation, service differentiation, and QoS guarantees. Various server mechanisms that provide QoS extensions, however, rely on external administrators to set the right parameter values for their desirable performance. Due to the complexity of handling varying workloads and bursty traffic, configuring such parameters optimally becomes a challenge. In this paper we describe an observation-based approach for self-managing web servers that can adapt to changing workloads while maintaining the QoS requirements of different classes. In this approach, the system state is monitored continuously and parameter values of various system resources---primarily the accept queue and the CPU---are adjusted to maintain the system-wide QoS goals. We implement our techniques using the Apache web server and the Linux operating system. We first demonstrate the need to manage different resources in the system depending on the workload characteristics. We then experimentally demonstrate that our observation-based system monitors such workload changes and adjusts the resource parameters of the accept queue and CPU schedulers in order to maintain the QoS requirements of the different classes
Seagull: Intelligent Cloud Bursting for Enterprise Applications
No full textEnterprises with existing IT infrastructure are beginning to employ a hybrid cloud model where the enterprise uses its own private resources for the majority of its computing, but then “bursts ” into the cloud when local resources are insufficient. However, current approaches to cloud bursting cannot be effectively automated because they heavily rely on system administrator knowledge to make decisions. In this paper we describe Seagull, a system designed to facilitate cloud bursting by determining which applications can be transitioned into the cloud most economically, and automating the movement process at the proper time. We further optimize the deployment of applications into the cloud using an intelligent precopying mechanism that proactively replicates virtualized applications, lowering the bursting time from hours to minutes. Our evaluation illustrates how our prototype can reduce cloud costs by more than 45 % when bursting to the cloud, and the incremental cost added by precopying applications is offset by a burst time reduction of nearly 95%.
Change Management in Enterprise IT Systems: Process Modeling and Capacity-optimal Scheduling
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