La congestion dans les réseaux est un phénomène qui peut influer sur la qualité de service ressentie par les utilisateurs. L’augmentation continue du trafic sur l’internet rend le phénomène de congestion un problème auquel l’opérateur doit répondre pour satisfaire ses clients. Les solutions historiques à la congestion pour un opérateur, comme le surdimensionnement des liens de son infrastructure, ne sont plus aujourd’hui viables. Avec l’évolution de l’architecture des réseaux et l’arrivée de nouvelles applications sur l’internet, de nouveaux paradigmes de contrôle de congestion sont à envisager pour répondre aux attentes des utilisateurs du réseau de l’opérateur. Dans cette thèse, nous examinons les nouvelles approches proposées pour le contrôle de congestion dans le réseau d’un opérateur. Nous proposons une évaluation de ces approches à travers des simulations, ce qui nous permet d’estimer leur efficacité et leur potentiel à être déployés et opérationnels dans le contexte d’internet, ainsi que de se rendre compte des défis qu’il faut relever pour atteindre cet objectif. Nous proposons également des solutions de contrôle de congestion dans des environnements nouveaux tels que les architectures Software Defined Networking et le cloud déployé sur un ou plusieurs data centers, où la congestion est à surveiller pour maintenir la qualité des services cloud offerts aux clients. Pour appuyer nos propositions d’architectures de contrôle de congestion, nous présentons des plateformes expérimentales qui démontrent le fonctionnement et le potentiel de nos solutions. / Network congestion is a phenomenon that can influence the quality of service experienced by the users. The continuous increase of internet traffic makes this phenomenon an issue that should be addressed by the network operator to satisfy its clients. The usual solutions to congestion, such as overdimensioning the infrastructure, are not viable anymore. With the evolution of the network architecture and the emergence of new internet applications, new paradigms for congestion control have to be considered as a response to the expectations of network users. In this thesis, we examine new approaches to congestion control in an operator’s network. We propose an evaluation of these approaches through simulations, which allows us to estimate their potential to be deployed and used over the internet, and allows us to be aware of the challenges in order to achieve this goal. We also provide solutions for congestion control in new environments such as Software- Defined Networking architectures and cloud computing deployed over many data centers, where congestion is to be monitored to maintain the quality of cloud services to its users. To support our proposals for congestion control architectures, we present experimental platforms that demonstrate the feasibility of our solutions.

No description available.

Computational fluid dynamics and heat transfer (CFD/HT) models have been employed as the dominant technique for the design and optimization of both new and existing data centers. Inviscid modeling has shown great speed advantages over the full Navier-Stokes CFD/HT models (over 20 times faster), but is incapable of capturing the physics in the viscous regions of the domain. A coupled inviscid-viscous solution method (CIVSM) for bounded domains has been developed in order to increase both the solution speed and accuracy of CFD/HT models. The methodology consists of an iterative solution technique that divides the full domain into multiple regions consisting of at least one set of viscous, inviscid, and interface regions. The full steady, Reynolds-Averaged Navier-Stokes (RANS) equations with turbulence modeling are used to solve the viscous domain, while the inviscid domain is solved using the Euler equations. By combining the increased speed of the inviscid solver in the inviscid regions, along with the viscous solver’s ability to capture the turbulent flow physics in the viscous regions, a faster and potentially more accurate solution can be obtained for bounded domains that contain inviscid regions which encompass more than half of the domain, such as data centers.

The data center industry currently focuses on initiatives to reduce its enormous energy consumption and minimize its adverse environmental impact. Modular data centers provide considerable operational flexibility in that they are mobile, and are manufactured using standard containers. This thesis aims at developing steady-state energy and exergy destruction models for modular data centers using four different cooling approaches: direct expansion cooling, direct and indirect evaporative cooling, and free air cooling. Furthermore, transient thermal response of these data centers to dynamic loads, such as varying server load through change in user requirement over the cloud, and/or to changes in outside weather conditions has been studied. The effect of server thermal mass has also been accounted for in developing the transient regime. The change in performance of the data center is reported through changes in the Power Usage Effectiveness (PUE) metric, and through change in the exergy destruction in the individual hot and cold aisles. The core simulation software used for this work is EnergyPlus, an open source software from the U.S. Department of Energy. Moreover, EnergyPlus is used as the simulation engine within the in-house developed software package Data Center EnergyPlus (DCE+).

Datacenter networks are not only larger but with new applications increasing the east-west traffic and the introduction of the spine leaf architecture there is an urgent need for high bandwidth, low cost, energy efficient interconnects. This paper will discuss the role integrated photonics can have in achieving datacenter requirements. We will review the state of the art and then focus on advances in optical switch fabrics and systems. The optical switch is of particular interest from the integration point of view. Current MEMS and LCOS commercial solutions are relatively large with relatively slow reconfiguration times limiting their use in packet based datacenter networks. This has driven the research and development of more highly integrated silicon photonic switch fabrics, including micro ring, Mach-Zehnder and MEMS device designs each with its own energy, bandwidth and scalability, challenges and trade-offs. Micro rings show promise for their small footprint, however they require an energy efficient means to maintain wavelength and thermal control. Latency requirements have been traditionally less stringent in datacenter networks compared to high performance computing applications, however with the increasing numbers of servers communicating within applications and the growing size of the warehouse datacenter, latency is becoming more critical. Although the transparent optical switch fabric itself has a minimal additional latency, we must also take account of any additional latency of the optically switched architecture. Proposed optically switched architectures will be reviewed.

La presente tesis describe el Proyecto de Diseño de una Red Over Ethernet sobre una red física DE 10 Gigabit Ethernet utilizando categoría 6A, demostrando la convergencia de estas dos tecnologías logrando el mayor rendimiento y cumpliendo con todas las normas internacionales y nacionales aplicados en un Data Center.

In this work a suggested method to reduce the energy consumption of the cooling system in a data center is modelled and evaluated. Introduced is different approaches to distributed airflow control, in which different amounts of airflow can be supplied in different parts of the data center (instead of an even airflow distribution). Two different kinds of distributed airflow control are compared to a traditional approach without airflow control. The difference between the two control approaches being the type of server rack used, either traditional ones or a new kind of rack with vertically placed servers. A model capable of describing the power consumption of the data center cooling system for these different approaches to airflow control was constructed. Based on the model, MATLAB simulations of three different server work load scenarios were then carried out. It was found that introducing distributed airflow control reduced the power consumption for all scenarios and that the control approach with the new kind of rack had the largest reduction. For this case the power consumption of the cooling system could be reduced to 60% - 69% of the initial consumption, depending on the workload scenario. Also examined was the effect on the data center of different parameters and process variables (parameters held fixed with the help of feedback loops), as well as optimal set point values.

Thesis (M.S. in Management)--Naval Postgraduate School, March 2010. / Thesis Advisor(s): Mehay, Stephen L. ; Hudgens, Bryan. "March 2010." Description based on title screen as viewed on April 26, 2010. Author(s) subject terms: Attrition, U.S. Air Force Pilots, Commissioning Source, Logit Model, Retention. Includes bibliographical references (p. 51-52). Also available in print.

abstract: Energy efficient design and management of data centers has seen considerable interest in the recent years owing to its potential to reduce the overall energy consumption and thereby the costs associated with it. Therefore, it is of utmost importance that new methods for improved physical design of data centers, resource management schemes for efficient workload distribution and sustainable operation for improving the energy efficiency, be developed and tested before implementation on an actual data center. The BlueTool project, provides such a state-of-the-art platform, both software and hardware, to design and analyze energy efficiency of data centers. The software platform, namely GDCSim uses cyber-physical approach to study the physical behavior of the data center in response to the management decisions by taking into account the heat recirculation patterns in the data center room. Such an approach yields best possible energy savings owing to the characterization of cyber-physical interactions and the ability of the resource management to take decisions based on physical behavior of data centers. The GDCSim mainly uses two Computational Fluid Dynamics (CFD) based cyber-physical models namely, Heat Recirculation Matrix (HRM) and Transient Heat Distribution Model (THDM) for thermal predictions based on different management schemes. They are generated using a model generator namely BlueSim. To ensure the accuracy of the thermal predictions using the GDCSim, the models, HRM and THDM and the model generator, BlueSim need to be validated experimentally. For this purpose, the hardware platform of the BlueTool project, namely the BlueCenter, a mini data center, can be used. As a part of this thesis, the HRM and THDM were generated using the BlueSim and experimentally validated using the BlueCenter. An average error of 4.08% was observed for BlueSim, 5.84% for HRM and 4.24% for THDM. Further, a high initial error was observed for transient thermal prediction, which is due to the inability of BlueSim to account for the heat retained by server components. / Dissertation/Thesis / M.S. Mechanical Engineering 2012

Made available in DSpace on 2014-06-12T15:56:09Z (GMT). No. of bitstreams: 2 arquivo2741_1.pdf: 2448903 bytes, checksum: 599fb23d0e11967dbc261ad018b22c3b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Quando o conceito de responsabilidade social começou a se popularizar, nos anos 90, muitos enxergavam a adoção dessas práticas apenas como uma ferramenta para promover uma imagem positiva das corporações na sociedade. Com o amadurecimento dessa política, veio a percepção dos empresários de que a utilização de meios de produção socialmente corretos também contribuía para elevar o desempenho dos negócios. Exemplos dessa tendência podem ser notados em empresas de, praticamente, todos os segmentos. No caso da informática, surgiu a Green Information Technology ou Tecnologia da Informação Verde, que chamaremos de TI Verde. Resumidamente, essa abordagem traz uma série de práticas para tornar o uso da computação mais sustentável e menos nocivo ao meio ambiente. Sabe-se que antes o desempenho e a disponibilidade eram as questões primordiais, hoje o ideal é encontrar um meio termo entre performance e eficiência no consumo. Nos Centros de Processamento de Dados (Data Centers), esse equilíbrio é um ponto crucial, dada a magnitude dos gastos necessários para o seu funcionamento. A proposta deste trabalho é apresentar uma visão das melhores práticas para a construção de um DC verde no complexo industrial de SUAPE. Com essa proposta em mente, independente de qual for a intenção dos gestores (redução de gastos ou real preocupação ambiental), o resultado da adoção das práticas verdes de TI aqui descritas parece caminhar sempre para a redução na emissão de poluentes e do consumo de recursos naturais