Paul Townend

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Analyzing behavioral patterns of workloads is critical to understanding Cloud computing environments. However, until now only a limited number of real-world Cloud datacenter tracelogs have been available for analysis. This has led to a lack of methodologies to capture the diversity of patterns that exist in such datasets. This paper presents the first(More)
Fault tolerance is an important property in Grid computing as the dependability of individual Grid resources may not be able to be guaranteed; also as resources are used outside of organizational boundaries, it becomes increasingly difficult to guarantee that a resource being used is not malicious in some way. As part of the e-Demand project at the(More)
Cloud computing presents exciting opportunities to foster research for scientific communities; virtual machine technology has a profound role in this. Among other benefits, virtual machine technology enables Clouds to offer large scale and flexible computing infrastructures that are available on demand to address the diverse requirements of scientific(More)
Service-orientation has been proposed as a way of facilitating the development and integration of increasingly complex and heterogeneous system components. However, there are many new challenges to the dependability community in this new paradigm, such as how individual channels within fault-tolerant systems may invoke common services as part of their(More)
Understanding the characteristics and patterns of workloads within a Cloud computing environment is critical in order to improve resource management and operational conditions while Quality of Service (QoS) guarantees are maintained. Simulation models based on realistic parameters are also urgently needed for investigating the impact of these workload(More)
Cloud computing providers are under great pressure to reduce operational costs through improved energy utilization while provisioning dependable service to customers; it is therefore extremely important to understand and quantify the explicit impact of failures within a system in terms of energy costs. This paper presents the first comprehensive analysis of(More)
An increasing range of industries has a growing dependence on software-based systems, many of which are safety-critical, real-time applications that require extremely high dependability. Multi-version programming has been proposed as a method for increasing the overall dependability of such systems however, the increased cost of using this approach may mean(More)
Cloud computing research is in great need of statistical parameters derived from the analysis of real-world systems. One aspect of this is the failure characteristics of Cloud environments composed of workloads and servers; currently, few metrics are available that quantify failure and repair times of workloads and servers at a large-scale. Workload metrics(More)