Adam P. Chester

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It is common that Internet service hosting centres use several logical pools to assign server resources to different applications, and that they try to achieve the highest total revenue by making efficient use of these resources. In this paper, multi-tiered enterprise systems are modelled as multi-class closed queueing networks, with each network station(More)
—Dynamic resource allocation has the potential to provide significant increases in total revenue in enterprise systems through the reallocation of available resources as the demands on hosted applications change over time. This paper investigates the combination of workload prediction algorithms and switching policies: the former aim to forecast the(More)
Application server clusters are often used to service high-throughput web applications. In order to host more than a single application, an organisation will usually procure a separate cluster for each application. Over time the utilisation of the clusters will vary, leading to variation in the response times experienced by users of the applications.(More)
The automatic allocation of enterprise workload to resources can be enhanced by being able to make what-if response time predictions whilst different allocations are being considered. We experimentally investigate an historical and a layered queuing performance model and show how they can provide a good level of support for a dynamic − urgent cloud(More)
This work is concerned with dynamic resource allocation for multi-tiered, cluster-based web hosting environments. Dynamic resource allocation is reactive, that is, when overloading occurs in one resource pool, servers are moved from another (quieter) pool to meet this demand. Switching servers comes with some overhead, so it is important to weigh up the(More)
—The scale and complexity of online applications and e-business infrastructures has led service providers to rely on the capabilities of large-scale hosting platforms, i.e., data centers. Dynamic resource allocation (DRA) algorithms have been shown to allow server resource allocation to be matched with application workload, which can improve server resource(More)
  • A Chester, S Xenos, Ryan, Li, J Fennessey, L Saunders
  • 2010
Increasing evidence suggests that providing students with both support and academic challenge is important to engagement, achievement, and retention. Effectively engaging and supporting first year students however is an ongoing tension, particularly when cohorts are large and diverse. This session describes a model of peer tutoring embedded in the(More)