The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Rodney Van Meter - One of the best experts on this subject based on the ideXlab platform.
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network attached storage architecture
Communications of The ACM, 2000Co-Authors: Garth A. Gibson, Rodney Van MeterAbstract:SAN with Fibre Channel network hardware that has a greater effect on a user’s purchasing decisions. This article is about how emerging technology may blur the network-centric distinction between NAS and SAN. For example, the decreasing specialization of SAN protocols promises SAN-like devices on Ethernet network hardware. Alternatively, the increasing specialization of NAS systems may embed much of the file system into storage devices. For users, it is increasingly worthwhile to investigate networked storage core and emerging technologies. Today, bits stored online on magnetic disks are so inexpensive that users are finding new, previously unaffordable, uses for storage. At Dataquest’s Storage2000 conference last June in Orlando, Fla., IBM reported that online disk storage is now significantly cheaper than paper or film, the dominant traditional information storage media. Not surprisingly, users are adding storage capacity at about 100% per year. Moreover, the rapid growth of e-commerce, with its huge global customer base and easy-to-use, online transactions, has introduced new market requirements, including bursty, unpredictable spurts in capacity, that demand vendors minimize the time from a user’s order to installation of new storage. In our increasingly Internet-dependent business and computing environment, network storage is the computer. NETWORK ATTACHED STORAGE ARCHITECTURE
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task force on network storage architecture internet attached storage devices
Hawaii International Conference on System Sciences, 1997Co-Authors: Rodney Van Meter, Steve Hotz, Gregory G FinnAbstract:Networks such as HiPPI, SSA and Fibre Channel are becoming the access technology of choice for peripherals such as disk drives, tape drives and disk arrays. These networks scale better than traditional I/O Channels, connecting more devices over greater distances and providing greater aggregate bandwidth. More complex protocols are required for network interfaces than for Channels. In most cases, specially developed protocols are used, rather than existing standards such as TCP/IP, due to perceived differences in functionality, focus, complexity and especially performance. We reason that most of these concerns either reflect misunderstanding of the IP suite or are being met as the suite evolves. We further argue that the benefits of using IP, including wide area connectivity, cross media bridging and reduced R&D, are substantial. Therefore, we feel that IP is an appropriate choice for a storage device and should be the protocol of choice for systems implementers.
Alex Alvarado - One of the best experts on this subject based on the ideXlab platform.
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regular perturbation on the group velocity dispersion parameter for nonlinear Fibre optical communications
Nature Communications, 2020Co-Authors: Vinicius Oliari, Erik Agrell, Alex AlvaradoAbstract:Communication using the optical Fibre Channel can be challenging due to nonlinear effects that arise in the optical propagation. These effects represent physical processes that originate from light propagation in optical Fibres. To obtain fundamental understandings of these processes, mathematical models are typically used. These models are based on approximations of the nonlinear Schrodinger equation, the differential equation that governs the propagation in an optical Fibre. All available models in the literature are restricted to certain regimes of operation. Here, we present an approximate model for the nonlinear optical Fibre Channel in the weak-dispersion regime, in a noiseless scenario. The approximation is obtained by applying regular perturbation theory on the group-velocity dispersion parameter of the nonlinear Schrodinger equation. The proposed model is compared with three other models using the normalized square deviation metric and shown to be significantly more accurate for links with high nonlinearities and weak dispersion.
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regular perturbation on the group velocity dispersion parameter for nonlinear Fibre optical communications
Nature Communications, 2020Co-Authors: Vinicius Oliari, Erik Agrell, Alex AlvaradoAbstract:Communication using the optical Fibre Channel can be challenging due to nonlinear effects that arise in the optical propagation. These effects represent physical processes that originate from light propagation in optical Fibres. To obtain fundamental understandings of these processes, mathematical models are typically used. These models are based on approximations of the nonlinear Schrodinger equation, the differential equation that governs the propagation in an optical Fibre. All available models in the literature are restricted to certain regimes of operation. Here, we present an approximate model for the nonlinear optical Fibre Channel in the weak-dispersion regime, in a noiseless scenario. The approximation is obtained by applying regular perturbation theory on the group-velocity dispersion parameter of the nonlinear Schrodinger equation. The proposed model is compared with three other models using the normalized square deviation metric and shown to be significantly more accurate for links with high nonlinearities and weak dispersion. Nonlinear effects have been studied in optical fiber communications Channels under various specified parameter regimes. Here, the authors develop an approximate model via perturbation that is more accurate for the highly nonlinear regime.
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Increasing the information rates of optical communications via coded modulation: a study of transceiver performance
Scientific Reports, 2016Co-Authors: Robert Maher, Domanic Lavery, Alex Alvarado, Polina BayvelAbstract:Optical Fibre underpins the global communications infrastructure and has experienced an astonishing evolution over the past four decades, with current commercial systems transmitting data rates in excess of 10 Tb/s over a single Fibre core. The continuation of this dramatic growth in throughput has become constrained due to a power dependent nonlinear distortion arising from a phenomenon known as the Kerr effect. The mitigation of Fibre nonlinearities is an area of intense research. However, even in the absence of nonlinear distortion, the practical limit on the transmission throughput of a single Fibre core is dominated by the finite signal-to-noise ratio (SNR) afforded by current state-of-the-art coherent optical transceivers. Therefore, the key to maximising the number of information bits that can be reliably transmitted over a Fibre Channel hinges on the simultaneous optimisation of the modulation format and code rate, based on the SNR achieved at the receiver. In this work, we use an information theoretic approach based on the mutual information and the generalised mutual information to characterise a state-of-the-art dual polarisation m -ary quadrature amplitude modulation transceiver and subsequently apply this methodology to a 15-carrier super-Channel to achieve the highest throughput (1.125 Tb/s) ever recorded using a single coherent receiver.
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a lower bound on the per soliton capacity of the nonlinear optical Fibre Channel
Information Theory Workshop, 2015Co-Authors: Nikita A Shevchenko, P Bayvel, Jaroslaw E Prilepsky, Stanislav A Derevyanko, Alex Alvarado, Sergei K TuritsynAbstract:A closed-form expression for a lower bound on the per soliton capacity of the nonlinear optical Fibre Channel in the presence of (optical) amplifier spontaneous emission (ASE) noise is derived. This bound is based on a non-Gaussian conditional probability density function for the soliton amplitude jitter induced by the ASE noise and is proven to grow logarithmically as the signal-to-noise ratio increases.
Domanic Lavery - One of the best experts on this subject based on the ideXlab platform.
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geometric shaping of 2 d constellations in the presence of laser phase noise
Journal of Lightwave Technology, 2021Co-Authors: Hubert Dzieciol, Eric Sillekens, P Bayvel, Gabriele Liga, Domanic LaveryAbstract:In this article, we propose a geometric shaping (GS) strategy to design 8, 16, 32, and 64 -ary modulation formats for the optical Fibre Channel impaired by both additive white Gaussian (AWGN) and phase noise. The constellations were optimised to maximise generalised mutual information (GMI) using a mismatched Channel model. The presented formats demonstrate an enhanced signal-to-noise ratio (SNR) tolerance in high phase noise regimes when compared with their quadrature amplitude modulation (QAM) or AWGN-optimised counterparts. By putting the optimisation results in the context of the 400ZR implementation agreement, we show that GS alone can either relax the laser linewidth (LW) or carrier phase estimation (CPE) requirements of 400 Gbit/s transmission links and beyond. Following the GMI validation, the performance of the presented formats was examined in terms of post forward error correction (FEC) bit-error-rate (BER) for a soft decision (SD) extended Hamming code (128, 120), implemented as per the 400ZR implementation agreement. We demonstrate gains of up to 1.2 dB when compared to the 64 -ary AWGN shaped formats.
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experimental demonstration of geometrically shaped constellations tailored to the nonlinear Fibre Channel
European Conference on Optical Communication, 2018Co-Authors: Eric Sillekens, Daniel Semrau, Domanic Lavery, P Bayvel, R I KilleyAbstract:A geometrically-shaped 256-QAM constellation, tailored to the nonlinear optical Fibre Channel, is experimentally demonstrated. The proposed constellation outperforms both uniform and AWGN-tailored 256-QAM, as it is designed to optimise the trade-off between shaping gain, nonlinearity and transceiver impairments.
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Increasing the information rates of optical communications via coded modulation: a study of transceiver performance
Scientific Reports, 2016Co-Authors: Robert Maher, Domanic Lavery, Alex Alvarado, Polina BayvelAbstract:Optical Fibre underpins the global communications infrastructure and has experienced an astonishing evolution over the past four decades, with current commercial systems transmitting data rates in excess of 10 Tb/s over a single Fibre core. The continuation of this dramatic growth in throughput has become constrained due to a power dependent nonlinear distortion arising from a phenomenon known as the Kerr effect. The mitigation of Fibre nonlinearities is an area of intense research. However, even in the absence of nonlinear distortion, the practical limit on the transmission throughput of a single Fibre core is dominated by the finite signal-to-noise ratio (SNR) afforded by current state-of-the-art coherent optical transceivers. Therefore, the key to maximising the number of information bits that can be reliably transmitted over a Fibre Channel hinges on the simultaneous optimisation of the modulation format and code rate, based on the SNR achieved at the receiver. In this work, we use an information theoretic approach based on the mutual information and the generalised mutual information to characterise a state-of-the-art dual polarisation m -ary quadrature amplitude modulation transceiver and subsequently apply this methodology to a 15-carrier super-Channel to achieve the highest throughput (1.125 Tb/s) ever recorded using a single coherent receiver.
Matthew T Okeefe - One of the best experts on this subject based on the ideXlab platform.
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implementing journaling in a linux shared disk file system
IEEE Symposium on Mass Storage Systems, 2000Co-Authors: Kenneth W Preslan, Andrew Barry, Jonathan Brassow, Erling Nygaard, David Teigland, Russell Cattelan, Adam Manthei, Seth Vanoort, Mike Tilstra, Matthew T OkeefeAbstract:In computer systems today, speed and responsiveness is often determined by network and storage subsystem performance. Faster, more scalable networking interfaces like Fibre Channel and Gigabit Ethernet provide the scaffolding from which higher performance computer systems implementations may be constructed, but new thinking is required about how machines interact with network-enabled storage devices. In this paper we describe how we implemented journaling in the Global File System (GFS), a shared-disk, cluster file system for Linux. Our previous three papers on GFS at the Mass Storage Symposium discussed our first three GFS implementations, their performance, and the lessons learned. Our fourth paper describes, appropriately enough, the evolution of GFS version 3 to version 4, which supports journaling and recovery from client failures. In addition, GFS scalability tests extending to 8 machines accessing 8 4-disk enclosures were conducted: these tests showed good scaling. We describe the GFS cluster infrastructure, which is necessary for proper recovery from machine and disk failures in a collection of machines sharing disks using GFS. Finally, we discuss the suitability of Linux for handling the big data requirements of supercomputing centers.
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a 64 bit shared disk file system for linux
IEEE Conference on Mass Storage Systems and Technologies, 1999Co-Authors: Kenneth W Preslan, Andrew Barry, Jonathan Brassow, Grant Erickson, Erling Nygaard, C J Sabol, Steven R Soltis, David Teigland, Matthew T OkeefeAbstract:In computer systems today, speed and responsiveness is often determined by network and storage subsystem performance. Faster, more scalable networking interfaces like Fibre Channel and Gigabit Ethernet provide the scaffolding from which higher performance implementations may be constructed, but new thinking is required about how machines interact with network-enabled storage devices. We have developed a Linux file system called GFS (the Global File System) that allows multiple Linux machines to access and share disk and tape devices on a Fibre Channel or SCSI storage network. We plan to extend GFS by transporting packetized SCSI commands over IP so that any GFS-enabled Linux machine can access shared network devices. GFS will perform well as a local file system, as a traditional network file system running over LP, and as a high-performance cluster file system running over storage networks like Fibre Channel. GFS device sharing provides a key cluster-enabling technology for Linux, helping to bring the availability, scalability, and load balancing benefits of clustering to Linux. Our goal is to develop a scalable, (in number of clients and devices, capacity, connectivity, and bandwidth) server-less file system that integrates IF-based network attached storage (NAS) and Fibre-Channel-based storage area networks (SAN). We call this new architecture Storage Area InterNetworking (SAINT). It exploits the speed and device scalability of SAN clusters, and provides the client scalability and network interoperability of NAS appliances. Our Linux port shows that the GFS architecture is portable across different platforms, and we are currently working on a port to NetBSD. The GFS code is open source (GPL) software freely available on the Internet at http://gfs.lcse.umn.edu.
Qinglin Qi - One of the best experts on this subject based on the ideXlab platform.
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A field programmable gate array implemented Fibre Channel switch for big data communication towards smart manufacturing
Robotics and Computer-Integrated Manufacturing, 2019Co-Authors: Fei Tao, Xiaofu Zou, Yue Tang, Qinglin QiAbstract:With the advances in new-generation information technologies (New IT), such as internet of things (IoT), cloud computing, and big data, etc., the big data-driven smart manufacturing era is coming. The volume of data generated and collected in manufacturing process is explosively growing, and big data need to be transmitted from data resources to a fog or a cloud platform. However, some practical limitations, such as overfull bandwidth, and data loss, confine the promotion of smart manufacturing. The limiting capacity of current data communication technologies becomes the bottleneck for smart manufacturing systems. In this paper, Fibre Channel (FC) switch based on field programmable gate array (FPGA) is designed and implemented due to its high speed, low latency, and high performance transmission capacities. Categories of comparative experiments were conducted and a case study is presented, which indicate that the designed FC switch meets the need of big data transmission for smart manufacturing. Its advanced capacity of transmitting and processing big data opens a bright perspective for smart manufacturing.
