A Case for Redundant Arrays of Hybrid Disks (RAHD)

Hybrid Hard Disk Drive was originally concepted by Samsung, which incorporates a Flash memory in a magnetic disk. The combined ultra-high-density benefits of magnetic storage and the low-power and fast read access of NAND technology inspires us to construct Redundant Arrays of Hybrid Disks (RAHD) to offer a possible alternative to today’s Redundant Arrays of Independent Disks (RAIDs) and/or Massive Arrays of Idle Disks (MAIDs). We first design an internal management system (including Energy-Efficient Control) for hybrid disks. Three traces collected from real systems as well as a synthetic trace are then used to evaluate the RAHD arrays. The trace-driven experimental results show: in the high speed mode, a RAHD outplays the purely-magnetic-disk-based RAIDs by a factor of 2.4–4; in the energy-efficient mode, a RAHD4/5 can save up to 89% of energy at little performance degradationPeer reviewe

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

How migrating 0.0001% of address space saves 12% of energy in hybrid storage

We present a simple, operating-\ud system independent method to reduce the num-\ud ber of seek operations and consequently reduce\ud the energy consumption of a hybrid storage\ud device consisting of a hard disk and a flash\ud memory. Trace-driven simulations show that\ud migrating a tiny amount of the address space\ud (0.0001%) from disk to flash already results\ud in a significant storage energy reduction (12%)\ud at virtually no extra cost. We show that the\ud amount of energy saving depends on which part\ud of the address space is migrated, and we present\ud two indicators for this, namely sequentiality and\ud request frequency. Our simulations show that\ud both are suitable as criterion for energy-saving\ud file placement methods in hybrid storage. We\ud address potential wear problems in the flash\ud subsystem by presenting a simple way to pro-\ud long its expected lifetime.\u

In-memory preprocessing of streaming sensory data - a partitioned relational database approach

In this paper we present a database architecture and an application area and method in detail. As sensory data stream in the database it is efficient to preprocess them in-memory before integrating in the repository in order to save storage I/O cost. After data are integrated, it is important to allow efficient quering based on data retrieval profile. This can also be supported by the presented database architecture by partitioning the database upon different criteria. It is mandatory to hide the internal partitioned architectural details from higher layers, so options to allow transparent quering options are also presented. We have implemented a test system and experimental results are also given

Analysis of Trade-Off Between Power Saving and Response Time in Disk Storage Systems

It is anticipated that in the near future disk storage systems will surpass application servers and will become the primary consumer of power in the data centers. Shutting down of inactive disks is one of the more widespread solutions to save power consumption of disk systems. This solution involves spinning down or completely shutting off disks that exhibit long periods of inactivity and placing them in standby mode. A file request from a disk in standby mode will incur an I/O cost penalty as it takes time to spin up the disk before it can serve the file. In this paper, we address the problem of designing and implementing file allocation strategies on disk storage that save energy while meeting performance requirements of file retrievals. We present an algorithm for solving this problem with guaranteed bounds from the optimal solution. Our algorithm runs in O(nlogn) time where n is the number of files allocated. Detailed simulation results and experiments with real life workloads are also presented

Workload-Adaptive Management of Energy-Smart Disk Storage Systems

Recent studies have identified disk storage systems as one of the major consumers of power in data centers. Many disk power management (DPM) schemes were suggested where the power consumed by disks is reduced by spinning them down during long idle periods. Spinning the disks down and up results in additional energy and response time costs. For that reason, DPM schemes are effective only if the disks experience relatively long idle periods and the scheme does not introduce a severe response time penalty. In this paper we introduce a dynamic block exchange algorithm which switches data between disks based on the observed workload such that frequently accessed blocks end up residing on a few"hot" disks thus allowing the majority of disks to experience longer idle periods. We validate the effectiveness of the algorithm with trace-driven simulations showing power savings of up to 60percent with very small response time penalties

High Energy Physics Forum for Computational Excellence: Working Group Reports (I. Applications Software II. Software Libraries and Tools III. Systems)

Computing plays an essential role in all aspects of high energy physics. As computational technology evolves rapidly in new directions, and data throughput and volume continue to follow a steep trend-line, it is important for the HEP community to develop an effective response to a series of expected challenges. In order to help shape the desired response, the HEP Forum for Computational Excellence (HEP-FCE) initiated a roadmap planning activity with two key overlapping drivers -- 1) software effectiveness, and 2) infrastructure and expertise advancement. The HEP-FCE formed three working groups, 1) Applications Software, 2) Software Libraries and Tools, and 3) Systems (including systems software), to provide an overview of the current status of HEP computing and to present findings and opportunities for the desired HEP computational roadmap. The final versions of the reports are combined in this document, and are presented along with introductory material.Comment: 72 page

TI VERDE – EFICIÊNCIA ENERGÉTICA DE DATA CENTER

O mercado competitivo em que as organizações estão inseridas exige constante adequação às novas tecnologias, redução de custos e melhoria de desempenho.  A Tecnologia da Informação (TI) Verde solicita uma visão global das operações de TI e de negócio para que, com análise apurada, possa apoiar as empresas nos itens já mencionados e questões relacionadas à eficiência no consumo de energia, provisionando e dimensionando recursos, efetuando controles sobre a operação e também cuidado com o meio ambiente. Algumas empresas já abordam este assunto, pois além da preocupação com a preservação dos recursos naturais, saem ganhando com melhor eficiência das operações de TI

Playout-järjestelmän arkistointi

Insinöörityön tarkoitus oli suunnitella ja toteuttaa sovellus, joka siirtää videomateriaalia Windows 2012 R2 -palvelimelta DAC ALTO -palvelimelle. Sovellus on osa playout-järjestelmää, jossa arkistoidaan videomateriaali, jota ei enää lähitulevaisuudessa käytetä. Sovellus siirtää tiedostoja määriteltyjen aikajaksojen väliltä automaattisesti sekä manuaalisesti käyttäjän määrittelemien päivien väliltä. Sovellukseen toteutettiin käyttöliittymä, josta ilmenee siirtymässä olevat tiedostot, arvioitu tiedostonsiirtonopeus ja tiedostonsiirron edistyminen. Sovellus ohjelmoitiin pääsääntöisesti C#-kielellä, ja sen käyttöliittymä pohjautui Windows Forms -kirjastoon. Insinöörityössä tarkasteltiin sovelluksen toteutuksen lisäksi myös arkistoinnin kannalta oleellisten komponenttien vuorovaikutusta työn tilaajan konkreettisessa playout-järjestelmässä. Insinöörityössä käytiin läpi playout-järjestelmässä liikkuvan videomateriaalin elinkaari vaiheittain videomateriaalin toimituksesta arkistointiin asti sekä se, kuinka sen eri vaiheet on toteutettu. Insinöörityön päätteeksi todettiin, että toteutettu sovellus oli toimiva ja se täytti työn tilaajan asettamat teknilliset määritelmät. Sovellusta jatkokehitetään työn tilaajan tarpeiden mukaanThe purpose of this thesis work was to design and implement an application that transfers video material from Windows 2012 R2 -server to DAC ALTO -server. The application is a part of a playout system, where its purpose is to archive video material no longer needed in the near future. The application archives the video files between set dates automatically and manually by the end user. A graphical user interface was implemented to the application that visualizes the estimated transfer speed and progression of the ongoing transaction and the files to be moved. The application was written in C# and its GUI as a Windows Forms application. In addition to going through the implementation of the application, the study also observed the interactions between the components relevant to the archiving process in the playout system. The study observed the life cycle of the video material that went through the play-out system and how each step had been implemented. The outcome of the study turned out to be a working solution and it met the client’s technical requirements. The application will be further developed when the client needs more functionalities or changes in it