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1、File-systemImplementationZhaoFangOperatingSystems-forthecollagestudentsGoalforToday?File-SystemStructure?File-SystemImplementation?DirectoryImplementation?Free-SpaceManagement?UnixFileManagement?LinuxVirtualFileSystem?WindowsFileSystemObjectives?Todescri
2、bethedetailsofimplementinglocalfilesystemsanddirectorystructures?Todescribetheimplementationofremotefilesystems?Todiscussblockallocationandfree-blockalgorithmsandtrade-offsFile-SystemStructure?Filestructure?Logicalstorageunit?Collectionofrelatedinformati
3、on?Filesystemresidesonsecondarystorage(disks)?Provideduserinterfacetostorage,mappinglogicaltophysical?Providesefficientandconvenientaccesstodiskbyallowingdatatobestored,locatedretrievedeasilyFile-SystemStructure?Diskprovidesin-placerewriteandrandomaccess
4、?I/Otransfersperformedinblocksofsectors(usually512bytes)?Filecontrolblock–storagestructureconsistingofinformationaboutafile?Devicedrivercontrolsthephysicaldevice?FilesystemorganizedintolayersTypicalsoftwareorganizationDeviceDrivers?Lowestlevel?Communicat
5、esdirectlywithperipheraldevices?ResponsibleforstartingI/Ooperationsonadevice?ProcessesthecompletionofanI/OrequestBasicFileSystem?PhysicalI/O?Primaryinterfacewiththeenvironmentoutsidethecomputersystem?Dealswithexchangingblocksofdata?Concernedwiththeplacem
6、entofblocks?ConcernedwithbufferingblocksinmainmemoryBasicI/OSupervisor?ResponsibleforallfileI/Oinitiationandtermination.?Controlstructuresdealwith?DeviceI/O,?Scheduling,?Filestatus.?SelectsandschedulesI/OwiththedeviceLogicalI/O?Enablesusersandapplication
7、stoaccessrecords?Providesgeneral-purposerecordI/Ocapability?MaintainsbasicdataaboutfileElementsofFileManagementFile-SystemImplementation?BootcontrolblockcontainsinfoneededbysystemtobootOSfromthatvolume?NeededifvolumecontainsOS,usuallyfirstblockofvolume?V
8、olumecontrolblock(superblock,masterfiletable)containsvolumedetails?Total#ofblocks,#offreeblocks,blocksize,freeblockpointersorarray?Directorystructureorganizesthefiles?Namesandinodenumbers,masterfiletableFile-SystemImplemen
