porting the arla file system to windows ntnew

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1、PortingtheArlafilesystemtoWindowsNTMagnusAhltorpRoyalInstituteofTechnologyahltorp@nada.kth.seLoveH¨ornquist-Astrand˚RoyalInstituteofTechnologylha@nada.kth.seAssarWesterlundSwedishInstituteofComputerScienceassar@sics.seAbstractThispaperdescribeshowweportedtheArlafilesystemtoWindow

2、sNT/2000.Win-dowsisverydifferentfromtheplatforms(differentflavorsofUnix)thatArlawaswrittenforbefore.Arlaconsistsofacomplexuserlanddaemon(arlad)andarathersimplekernel-module(xfs).ArladneededverylittleworktobeabletoworkonWindowsbecauseweusedCygwin.TheWindowskernel-modulewaswritten

3、fromscratchunderinfluencefromtheearlierUnixkernel-modules.Sinceeverthingwasdifferentittookverylongtimetocompletetheworkwithxfs.Aproblemisthatthereislittleexamplecodeavailabletobeusedasreferenceandinspiration.1IntroductionWritingakerneldriverforanewoperatingsystemisquiteanadventu

4、re.Theba-sicprincipleofhowacomputeroperatesisthesame,butalmosteverythingelsehaschanged.Anewoperatingsystemisanewparadigmandtherearenewcommoncon-structsthatoneneedstolearn.Oftenthisfeelingthataconstructwouldbemucheasiertocreatewiththepreviousoperatingsystembubbletothesurfaceofco

5、nsciousness.Butthereisalsothisnew(sometimesscary)thoughtenteringyourmind:“Wow,thismightbeuseful,almostbeautiful.”.2AFSandCodaAFS[8]wasdevelopedatCarnegieMellonUniversity(CMU).AFSwascreatedaspartofaprototypecomputingenviromentforUniversitiesinacollaborativeeffortbetweenIBMandCar

6、negieMellon.ScalabilityisoneofthemainpropertiesofAFS.Itwasdesignedtohandlemorethen5000concurrentworkstations.OtherimportantfeaturesofAFSislocationtrans-parency,compatibilitywithexistingoperatingsysteminterfaces,andusermobility.Securityisanimportantdesignconsideration,andthemech

7、anismsforitdonotassumethattheworkstationsorthenetworkaresecure.Coda[7]isdesignedwiththesameprinciplesasAFS,butwithemphasisofveryhighavailability.Thisisdonebyusingoptimisticwritingregardingconsistency.3TheArchitectureofArlaTheArlaclientisdividedintotwocomponents,akernelmodule(xf

8、s)andauser-leveldaemon(arlad),seefigure1.Thekernelmodul