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)
Internet service providers (ISPs) usually use several server pools to host different web applications, to ensure smooth system management and minimum interference between applications. The workload demand in each of the pools can vary dramatically due to a number of factors, including timing and the types of the hosted applications. Therefore, it is(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 workload(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)
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 prevalence of cloud computing environments and the ever increasing reliance of large organisations on computational resources has meant that service providers must operate at unprecedented scales and levels of efficiency. Dynamic resource allocation (DRA) policies have been shown to allow service providers to improve resource utilisation and operational(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)
Acknowledgements The authors acknowledge the support and funding from the JISC " s Research Infrastructure programme. The authors thank in particular the following individuals and organisations for their time, support and input during the course of this review. We apologise to others who have also contributed, but whose names have been omitted. Executive(More)
In dynamic resource allocation systems, servers are moved between pools when overloading is detected. In this work, we investigate the impact to such systems of combining three adaptive monitoring techniques. First we employ two well known switching policies -- the Proportional Switching Policy (PSP) and the Bottleneck Aware Switching Policy (BSP) -- to(More)