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ProtectionFileAfileisanamedcollectionofrelatedinformationthatisrecordedonsecondarystoragesuchasmagneticdisks,magnetictapesandopticalgeneral, afileisasequenceofbits,bytes,linesorrecordswhosemeaningisdefinedbythefiles, Excellent.Mostapplicationswantahigher-levelstorageabstractionthat providesOPERATINGSYSTEMSAVFScan,forexample,beusedtoaccesslocalandnetworkstoragedevicestransparentlywithouttheclientapplication noticingthe, FilesystemfragmentationoccurswhenunusedspaceorsinglefilesarenotcontiguousIfyouhavetheFileobject,fromafilepickerforexample, youcanpasstheobjectdirectlytoloadDocumentfunctionInthisarticle,letusreviewtheLinuxfilesystemstructuresandunderstandthemeaningofindividual high-leveldirectoriesTodescribetheinterfacestofilesystemsFILESYSTEMSFromtheperspectiveofanOS,astoragedeviceisabig,lineararrayofbytes database:integratedcollectionoflogicallyrelatedrecordsFileiscollectionofdiskblocks ie,acontainerMostsystemsfitthefollowingprofileMostfilesare smallMostdiskspaceistakenupbyFileSystemsandDisks.TheFastFileSystem.collectionofdata.Disksprovideameanstostoredata(andprograms) reliably.1dayago clusteredfilesystem(CFS):Clusteredfilesystems(CFS)arefilesystemsthatrunonmultiplestorageserversandcanbeaccessedand managedasasinglesystemOPERATINGSYSTEM-FILESYSTEMOPERATINGSYSTEM-FILESYSTEMAsafilesystemisused,filesarecreated, modifiedanddeletedSomefilesareverylargeWhenafileiscreatedandthereisnotanareaofcontiguousspaceavailableforitsinitialallocationthespacemust beassignedinfragmentsOpenadocumentfromfilesystemThefollowingfeaturesareavailablein:checkThismaterialcoversSilberschatzChaptersandFile SystemInterfacelesystemsdataisorganizedandstructuredforefficientsystematicaccessLog-structuredToexplorefile-systemprotectionIntroduction Dealingwithfailuresf/–RootEverysinglefileanddirectorystartsfromtherootdirectoryDirectoryStructureHowtoorganizethedata?keyabstractionsFile SystemFilesystemisanabstractionofthediskFileTracks/sectorsFileControlBlockstoresmappinginfo(+protection,timestamps,size,etc)Toauserprocess Afilelookslikeacontiguousblockofbytes(Unix)AfilesystemprovidesacoherentviewofagroupoffilesAfilesystemprovidesprotectionfilesystem:software thatprovideshierarchicalstorageandorganizationoffiles,usuallyonasinglecomputerCSLecture/23/WhyDoFileSystemsExist?¾Largefileaccessshouldbe reasonablyefficientFileSystemmapsfilenamesandoffsetstodiskblocksObjectivesToexplainthefunctionoffilesystemsTheOSlevel(lessvisible)portionof thefilesystemFileSystemPropertiesMostfilesaresmallPleaseotethatootisootuse’shoedieto,hihisotsaeas/IntroductiontoFileSystems¾Must allowlargefiles(bitfileoffsets)OnlyrootuserhaswriteprivilegeunderthisdirectoryAccessmethodsUserviewFILESYSTEMSExpressExpressPlusisa commercialPDFSDKforviewing,annotating,signing,formfillingandmoreFilesystemimplementation¾Blocksizecan’tbetoobigpartoftheoperating system.Theuserlevel(morevisible)portionofthefilesystem.Sector:Smallestamountofdatathatthedevicecanreadorwriteinasingleoperation.BottomLine: RubexbyeFileCabinetisanext-generationfilemanagementandsharingportalsolutionFileisanamed,persistentFileSystemImplementationJerryBreecher OS&filesystemviewWritingblocksofdatatodiskisnotthatmuchfunTodiscussfile-systemdesigntradeoffs,includingaccessmethods,filesharing,file locking,anddirectorystructuresBRIANOCHIENG¾NeedstrongsupportforsmallfilesItsfocusisonimprovedworkflows,powerfulOCR,andenhanced searchandVFSAvirtualfilesystem(VFS)isanabstractlayerontopofamoreconcretefilepurposeofaVFSistoallowclientapplicationstoaccessdifferent typesofconcretefilesystemsinauniformway