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1、CHAPTER7StorageHardDisksHardDisksLow-levelformat-organizesbothsidesofeachplatterintotracksandsectorstodefinewhereitemswillbestoredonthedisk.Partitioning:divideharddiskintoseparateareascalledpartitions;eachpartitionfunctionsasifitwereaseparateharddiskdrive.High
2、-levelformatdefinesthefileallocationtable(FAT)foreachpartition,whichisatableofinformationusedtolocatefilesonthedisk.HardDisksUsethicker,metallicplattersforstorageFasterthanafloppydisketteLargecapacitySensitiveinstrumentsLowLevelFormattingLowlevelformatscansdis
3、kfordefectsandsetsasidesectorswithdefectssotheyarenotusedfordata.IDEdrivesshouldneverbelowlevelformattedbyauserortechnician.Onlyhighlevelformatnecessary.HardDriveFloppiesTwosizes3.5inch5.25inch3.5inchholds1.44MBforHighdensityand750KBforDoubleDensityConnectedwi
4、th34pinribboncableTwoFloppyDrivespossibleHastwistincabletodistinguishAdrivefromBdriveSCSIPronouncedScuzzySmallComputerSystemsInterfaceForwiderangeofperipheraldevices,includingharddisks,tapedrives,opticaldrives,CD-ROMsanddiskarrays.8devicescanconnecttoadaisycha
5、inThischainmustbeterminatedatbothendsEachdeviceonchainisassigneduniquedeviceIDnumberthatisdeterminedbyjumpersorDIPswitchesInstallingandconfiguringSCSISCSIbussupports8devicesThereareeightSCSIIDsnumbered0through7ID7isalwaysreservedfortheSCSIhostadapterSCSIharddi
6、sk,ifusedasabootdrive,isassignedSCSIID0IfyouhavebothIDEandSCSIharddrive,IDEdriveshouldbebootdriveTypesofSCSIsSCSI1-5MBtransferrate,Centronics50pinorDB25,has8bitbusSCSI2-alsoSCSIFastWide,includes16bitbus,calledWideSCSI,andtwiceasfasttransferrateSCSI3-IncludesUl
7、traSCSI,WideUltraSCSI,andUltra2SCSI,16bitbuswithupto80MBpstransferrateRAIDRedundantArrayofIndependentDisksCategoryofdiskdrivesthatemploys2ormoredrivesincombinationforfaulttolerance(errorrecovery)10levelsofRAID3ontestwillbe:RAID0,RAID3,RAID5RAIDcontinuedRAID0-S
8、tripeddiskwithoutparityRAID3-ParalleltransferwithparityRAID5-DatastripingwithparityHowDataisOrganizedonDiskTracks-circularareasofthediskLengthofatrackonecircumferenceofdiskOver1000
