Performance Evaluation of NFS over a Wide-Area Network

National audienceThe Cloud and Big Data movements triggered a move to more centralized, remote storage resources. However, the use of such remote resources raises a number of challenges at the protocol level. In this paper, we first evaluate the influence of several factors, including network latency, on the performance of the NFS protocol. Then, we explore how statistical methods such as a fractional factorial design of experiments could have helped to drastically reduce the number of required experiments while still providing a similar amount of information about the impact of the factors

A File Allocation Strategy for Energy-Efficient Disk Storage Systems

Exponential data growth is a reality for most enterprise and scientific data centers.Improvements in price/performance and storage densities of disks have made it both easy and affordable to maintain most of the data in large disk storage farms. The provisioning of disk storage farms however, is at the expense of high energy consumption due to the large number of spinning disks. The power for spinning the disks and the associated cooling costs is a significant fraction of the total power consumption of a typical data center. Given the trend of rising global fuel and energy prices and the high rate of data growth, the challenge is to implement appropriateconfigurations of large scale disk storage systems that meet performancerequirements for information retrieval across data centers. We present part of the solution to this challenge with an energy efficient file allocation strategy on a large scale disk storage system. Given performance characteristics of thedisks, and a profile of the workload in terms of frequencies of file requests and their sizes, the basic idea is to allocate files to disks such that the disks can be configured into two sets of active (constantly spinning), and passive (capable of being spun up or down) disk pools. The goal is to minimize the number of active disks subject to I/O performance constraints. We present an algorithm for solving this problem with guaranteed bounds from the optimal solution. Our algorithm runs in O(n) time where n is the number of files allocated. It uses a mapping of our file allocation problem to a generalization of the bin packing problem known as 2-dimensional vector packing. Detailed simulation results are also provided

Implantação de infraestrutura como serviço em uma nuvem computacional privada

Trabalho de conclusão de curso (graduação)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2016.O aumento da complexidade de aplicações e sistemas resulta em uma procura maior por recursos computacionais (poder de processamento, espaço de armazenamento, etc.). Consequentemente, novos paradigmas e conceitos de computação surgem, e a computação em nuvem é um deles. Esse novo conceito visa oferecer serviços sobre demanda pela Internet, as chamadas nuvens computacionais. Os serviços podem ser categorizados em três modelos: infraestrutura, plataforma e software como serviço. Este trabalho tem como foco o contexto de nuvens privadas que fornecem infraestrutura como serviço. Para isso, foi realizado um estudo sobre as principais plataformas de implantação para nuvens de infraestrutura. A proposta foi a implantação de uma nuvem privada de infraestrutura no laboratório LABID do departamento de Ciências da Computação da Universidade de Brasília. A plataforma CloudStack foi utilizada para a implantação da nuvem e, depois, foi avaliado o funcionamento e o comportamento através de testes funcionais e de desempenho. Este trabalho foi importante para garantir a infraestrutura interna de nuvem para os alunos e os pesquisadores do LABID, pois proporcionou a implantação de um ambiente de nuvem privada, que foi integrado a um ambiente de federação de nuvens pela plataforma BioNimbuZ.The increase in the complexity of applications and systems results in greater demand for computing resources (processing power, storage, etc.). Consequently, new computing concepts and paradigms arise and cloud computing is one of them. This new concept aims to offer services on-demand via the internet and can be categorized into three models: infrastructure-, platform- and software-as-a-service. This work focuses on the context of private clouds providing infrastructure-as-aservice. A study of the major platforms for infrastructure cloud services was carried out, with the proposal of implementing a private infrastructure cloud in the LABID laboratory of the Computer Science Department of the University of Brasília. The CloudStack framework was used to implement the cloud and the operation and behaviour of the system were evaluated through functional and performance tests. This paper was of particular importance to LABID’s students and researchers since it led to the implementation of an internal cloud environment which was then integrated into a cloud federation by the BioNimbuZ platform

A performance comparison of NFS and iSCSI for IP-networked storage

IP-networked storage protocols such as NFS and iSCSI have become increasingly common in to-day’s LAN environments. In this paper, we exper-imentally compare NFS and iSCSI performance for environments with no data sharing across ma-chines. Our micro- and macro-benchmarking results on the Linux platform show that iSCSI and NFS are comparable for data-intensive work-loads, while the former outperforms latter by a factor of two or more for meta-data intensive workloads. We identify aggressive meta-data caching and aggregation of meta-data updates in iSCSI to be the primary reasons for this perfor-mance difference and propose enhancements to NFS to overcome these limitations.