Introductiontothetapedrive
Theautomaticloadingtapedriveisactuallyacombinationoftapeandtapedrive.Theautoloaderisatapedriveandautomatictapechangerlocatedinasinglemachine.Itcanpickuptapesfromacassettecontainingmultipletapesandputthemintothedrive,orperformthereverseprocess.Itcanbackupdataof100GB-200GBormore.Auto-loadingtapedrivescansupportroutinebackupprocessesandautomaticallyloadnewtapesfordailybackuptasks.Asmallcompanywithaworkgroupservercanuseanautoloadertoautomatebackuptasks.
Theprincipleoftapestorage
Tapeisoneofthecommonlyusedstoragemediawiththelowestunitstorageinformationcost,thelargestcapacity,andthehighestdegreeofstandardizationamongallstoragemedia.Ithasgoodinterchangeabilityandiseasytostore.Inrecentyears,duetotheuseofcodingtechnologywithhigherrorcorrectioncapabilityandthewrite-readchanneltechnology,thereliabilityoftapestorageandthespeedofreadingandwritinghavebeengreatlyimproved.Accordingtotheworkingprincipleofreadingandwritingtapes,itcanbedividedintospiralscanningtechnology,linearrecording(dataflow)technology,DLTtechnologyandmoreadvancedLTOtechnology
Spiralscanningreadingandwritingtechnology:
ThemagnetictapereadingandwritingtechnologythatreadsandwritesdataonthetapebyspiralscanningisbasicallysimilartothatofaVCR.Thetapeiswoundaroundmostofthedrumandadvanceshorizontallyatalowspeed,whilethedrumisreversedduringthetapereadingandwritingprocess.High-speedrotation,themagneticheadinstalledonthesurfaceofthedrumcompletesthedataaccessandread-writeworkduringtherotation.Themagneticheadmaintainsaninclinationangleof15degreeswiththetapeduringreadingandwriting,andthetracksarearrangedinparallelonthetapeataninclinationangleof75degrees.Usingthisread-writetechnologycanobtainmoredatachannelsonthesametapearea,makefulluseoftheeffectivestoragespaceofthetape,andthushaveahigherdataaccessdensity.
Linearrecordingread-writetechnology:
Thetaperead-writetechnologyforreadingandwritingdataonthetapeinalinearrecordingmodeisbasicallythesameasthatofataperecorder,paralleltotheheadThehigh-speedmovingmagnetictapeskimmedthestationarymagneticheadfordatarecordingorreadingoperations.Thistechnologycanmakethedesignofthedrivesystemsimple,andthereadandwritespeedislow,butbecausethedatarecordingtrackonthetapeisparalleltobothsidesofthetape,thedatastorageutilizationrateislow.Inordertoeffectivelyimprovetheutilizationrateandread/writespeedofthetape,peoplehavedevelopedamulti-headparallelread/writemethodtoincreasetherecordingdensityandtransmissionrateofthetape.However,thedesignofthedrivehasbecomeextremelycomplicatedandthecosthasalsoincreased.
Digitallineartapetechnology:
DLTisanadvancedstoragetechnologystandard,including1/2-inchtape,linearrecordingmethod,andpatentedtapeimportKeytechnologiessuchasdevicesandspecialtapecassettes.ThetapedriveusingDLTtechnologyhas128tracksonatapewithatapelengthof1828feetandabandwidthof1/2inch.Theuncompressedcapacityofasingletapecanbeashighas20GB,andthecapacitycanbedoubledaftercompression.
Linearopentapetechnology:
Thisisahigh-techtapeprocessingtechnologysupportedbythethreemajorstorageequipmentmanufacturingcompaniesofIBM,HP,andSeagate.ItCangreatlyincreasetheamountoftapebackupdata.LTOtapecanincreasethecapacityofthetapeto100GB,ifcompressed,itcanreach200GB.LTOtechnologycannotonlyincreasethechanneldensityofthetape,butalsomakeoverallimprovementsintheheadandservostructure.LTOtechnologyusesanadvancedtrackservotrackingsystemtoeffectivelymonitorandcontroltheprecisepositioningoftheheadandpreventmiswritingofadjacenttracks.Theproblemistoachievethepurposeofincreasingthetrackdensity.
Typesoftapes
Thetapescanbedividedintosixspecificationsaccordingtotheworkingprincipleofreadingandwritingtapes.TwoofthemareDAT(4mm)tapedrivesforworkgroupleveland8mmtapedrivesfordepartmentlevel.Theotherfouraredevicesdesignedwithdatastreamstoragetechnology.TheyusesingleThemagneticheadreadandwritemethod,thetapewidthis1/4inch,TravanandDCseriesforlow-endapplications,andthemulti-headreadandwritemethod,thetapewidthis1/2inch,DLTandIBM's3480/forhigh-endapplications3490/3590seriesandsoon.
1/4-inchtapereel:
QIC(QuarterInchCartridge:1/4-inchtape)tapeisatapewithabandwidthof1/A4-inchcassettetapewithacassette,alsocalleda1/4-inchtape.Ithastwospecifications,namelyDC6000andDC2000.Amongthem,thedriveoftheDC6000tapeis5.25inches,whichhasbeeneliminated.ThedriveofDC2000tapeisonly3.5inches,thedrivepriceislow,thestandardizationishigh,andthemanufacturersarecompatiblewitheachother.ThestoragecapacityofaboxofDC2000tapeisgenerally400MB,whichisoneofthemostusedtapesatpresent.
DigitalAudioTape:
DAT(DigitalAudioTape:DigitalAudioTape)tape,themagneticbandwidthis0.15inches(4mm),alsocalled4mmtape.Becausethetapestoragesystemusesspiralscanningtechnology,thetapehasahighstoragecapacity.DATtapesystemsgenerallyusewriteandreadandcompressiontechnology,whichnotonlyimprovesthereliabilityanddatatransmissionrateofthesystem,butalsoincreasesthestoragecapacity.Atpresent,thestoragecapacityofaboxofDATtapescanreach12GB.Atthesametime,manymanufacturersofDATtapesanddrivesareapromisingdatabackupproduct.
8mmtape:
Itisalarge-capacitytapethatisonlydevelopedbyExabyteandissuitableforlargeandmedium-sizednetworksandmulti-usersystems.The8mmtapeanditsdrivealsousespiralscanningtechnology,andthetapeiswider,sothestoragecapacityisextremelyhigh,themaximumcapacityofatapecanreach14GB.Butthebrandissingleandtherearefewertypes.
1/2inchtape:
ThistypeoftapeisdividedintoDLT(digitallineartape)tapeandIBM3480/3490/3590seriestape..DuetotherapiddevelopmentofDLTtapetechnology,ithasbecomeanimportantstandardfornetworkbackuptapedrivesandtapelibrarysystems,andbecauseofitslargecapacity,highspeedanduniquedevelopmentpotential,ithasbecometheleaderinmediumandhighbackupsystems.DLTtapeshaveacapacityofupto35GBpercartridge,andthecostperunitcapacityislow;IBM3480/3490/3590seriestapesareproducedbyIBM,andthestoragecapacityofeachcartridgecanreach10GB.Thecorrespondingdrivesystemisactuallyatapelibrary.Storemultipletapes,anditsmanipulatorcanautomaticallyselectanyoneofthemtothedrive.