720 research outputs found

    Service Isolation vs. Consolidation: Implications for Iaas Cloud Application Deployment

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    Service isolation, achieved by deploying components of multi -tier applications using separate virtual machines (VMs), is a common \u27best\u27 practice. Various advantages cited include simpler deployment architectures, easier resource scalability for supporting dynamic application throughput requirements, and support for component-level fault tolerance . This paper presents results from an empirical study which investigates the performance implications of component placement for deployments of multi -tier applications to Infrastructure-as-a- Service (IaaS) clouds. Relationship s between performance and resource utilization (CPU, disk, network) are investigated to better understand the implications which result from how applications are deployed. All possible deployments for two variants of a multi -tier application were tested, one computationally bound by the model, the other bound by a geospatial database. The best performing deployments required as few as 2 VMs, half the number required for service isolation, demonstrating potential cost savings with service consolidation. Resource use (CPU time, disk I/O, and network I/O) varied based on component placement and VM memory allocation. Using separate VMs to host each application component resulted in performance overhead of ~1 -2%. Relationships between resource utilization an d performance were harnessed to build a multiple linear regression model to predict performance of component deployments. CPU time, disk sector reads, and disk sector writes are identified as the most powerful performance predictors for component deployments

    Performance Modeling to Support Multi-Tier Application Deployment to Infrastructure-As-A-Service Clouds

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    Infrastructure-as-a-service (IaaS) clouds support migration of multi-tier applications through virtualization of diverse application stack(s) of components which may require various operating systems and environments. To maximize performance of applications deployed to IaaS clouds while minimizing deployment costs, it is necessary to create virtual machine images to host application components with consideration for component dependencies that may affect load balancing of physical resources of VM hosts including CPU time, disk and network bandwidth. This paper presents results of an investigation utilizing physical machine (PM) and virtual machine (VM) resource utilization statistics to build performance models to predict application performance and rank performance of application component deployment configurations deployed across VMs. Our objective was to predict which component compositions provide best performance while requiring the fewest number of VMs. Eighteen individual resource utilization statistics were investigated for use as independent variables to predict service execution time using four different modeling approaches. Overall CPU time was the strongest predictor of execution time. The strength of individual predictors varied with respect to the resource utilization profiles of the applications. CPU statistics including idle time and number of context switches were good predictors when the test application was more disk I/O bound, while disk I/O statistics were better predictors when the application was more CPU bound. All performance models built were effective at determining the best performing service composition deployments validating the utility of our approach

    Migration of Multi-Tier Applications to Infrastructure-As-A-Service Clouds: An Investigation Using Kernel-Based Virtual Machines

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    To investigate challenges of multi -tier application migration to Infrastructure -as-a- Service (IaaS) clouds we performed an experimental investigation by deploying a processor bound and input -output bound variant of the RUSLE2 erosion model to an IaaS base d private cloud. Scaling the applications to achieve optimal system throughput is complex and involves much more than simply increasing the number of allotted virtual machines (VMs). While scaling the application variants a series of bottlenecks were encountered unique to an application\u27s processing, I/O, and memory requirements, herein referred to as an application\u27s profile. To investigate the impact of provisioning variation for hosting multi -tier applications we tested four schemes of VM deployments across the physical nodes of our cloud. Performance degradation was more pronounced when multiple I/O or CPU resource intensive application components were co -located on the same physical hardware. We investigated the virtualization overhead incurred using Kernel -based virtual machines (KVM) by deploying our application variants to both physical and virtual machines. Overhead varied based on the unique characteristics of each application\u27s profile. We observed ~112% overhead for the input/output bound application and just ~ 10 % overhead for the processor bound application. Understanding an application\u27s profile was found to be important for optimal IaaS -based cloud migration and scaling

    Community Resilience to Climate Change : Outcomes of the Scottish Borders Climate Resilient Communities Project

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    Aims and Objectives: This report presents findings from an action research project conducted in the Scottish Borders between May 2015 and September 2016. The project aimed to:1) Support a local process of community change through building partnerships, learning and capacity building; and2) Understand the critical factors involved in facilitating the development of community resilience to climate change to draw out key levers for change nationally.The project was a collaboration between the University of Dundee, the Scottish Borders Council, Tweed Forum, Southern Uplands Partnership, International Futures Forum and the Scottish Association of Marine Sciences. It worked with three communities that had experience of flooding in the Borders council area and involved bringing together diverse organisations and community members in workshops and other activities
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