Maxtor 5120 manual

GLOSSARY

CYLINDER

Onseveraldisksurfacessharingacommonrotationalaxis,theaggregateoftracksata givenradialposition.Asetofdisktracksthataresimultaneouslyunderthesetofread/ writeheads.Thisthree-dimensionalstoragevolumecanbeaccessedafterasingleseek.

CYLINDER ZERO

Theoutermostcylinderinadrivethatcanbeusedfordatastorage.

D

DATA

Anorderedcollectionofinformation.Inaspecificcase,itistheinformationprocessed byacomputer.

DATA SEPARATOR

Anelectroniccircuitwhichdecodesplaybackdataandproducesseparateclockanddata bits.Sometimesincorrectlyusedtodenotedatasynchronizer.

DATA SYNCHRONIZER

Anelectroniccircuitproducingaclocksignalthatissynchronouswiththeincoming datastream.Thisclocksignalisthenusedtodecodetherecordingcodebeingusedinto userdata.

DATA TRANSFER RATE

Inadiskortapedrive,therateatwhichdataistransferredtoorfromthestorage media.Itisusuallygiveninthousandsofbitspersecond(Kbit/second)ormillionsof bitspersecond(Mbit/second).

DEDICATED LANDING ZONE

Adesignatedradialzoneonthediskwherecontactstartingandstoppingoccurby design.

DEDICATED SERVO

Aservoschemeinwhichaprerecordedpatternonanotherwiseunuseddisksurface providespositioninformationtotheservocircuitrybymeansofaheadreadingthat surface.

DEFECT

Amagneticimperfectioninarecordingsurface.

DEFECT MANAGEMENT

Ageneralmethodologyofavoidingdataerrorsonarecordingsurfacebyavoidingthe useofknownbadareasofmedia.Usuallydefectivesectorsortracksareretiredanddata arewritteninalternatelocations.Severalalgorithmsarepossiblesuchas“sector slipping,”or“sparesectorpertrack.”

DEFECT MAP

Alistofdefectsthatfallwithinapass/failcriteriaofauser.Thislistisusuallyusedbyan operatingsystemoradiskdrivecontrollerfordefectmanagement.

DEFECT SKIPPING

Adefectmanagementschemeforavoidingsurfacedefects.Ithasdatawrittenbeforeand afterthedefect,insteadofusingalternatetracksorsectorstoavoiduseofthedefective area.

DENSITY

Generally,recordingdensity.Seeareal,bit,andstoragedensity.

DC ERASE

ThemethodoferasingatrackusingaDCwrite/erasecurrentthrougheitheraRead/ WriteorErasehead.

DIGITAL

Anysystemthatprocessesdigitalbinarysignals(havingonlyvaluesofa1or0;usually inbitsandbytes)ratherthananalogsignals(signalsthatcanhavemanyvalues)

DIGITAL MAGNETIC RECORDING

Seemagneticrecording.

DIRECT ACCESS

Accessdirectlytomemorylocation.(Seerandomaccess).

DIRECT MEMORY ACCESS

Ameanofdatatransferbetweenthedeviceandhostmemorywithoutprocessor intervention.

DIRECTORY

Alistingoffilesmaintainedbythediskoperationsystem(DOS)oradatabase managementsystemtoenableausertoquicklyaccessdatafiles.

DISK

Aflat,circularpieceofmetal(usuallyaluminum)orplastic(usuallymylar)witha magneticcoatinguponwhichinformationcanberecorded.(See,forexample,floppy diskorWinchesterdisk)

DISK DRIVE OR DISK MEMORY DEVICE

Thetotalelectromechanicalstoragedevicecontainingdisksandread/writeheads,head positioningmechanism,drivemotor,andelectronics.

DISK PACK

Anumberofmetaldiskspackagedinacanisterforremovalfromthediskdrive (predecessorofWinchestertechnology).

DISK OPERATING SYSTEM (DOS) Themastercomputersystemprogramthatschedulestasks,allocatesthecomputersystem resources,controlsaccessestomassstoragedevices,managesfiles,andsoforth.Typical diskoperatingsystemsincludeCP/M,MS-DOS,andUNIX.

DISK STORAGE

Auxiliarymemorysystemcontainingdiskdrives.

DISK TRANSFER RATE

Theratethatdigitaldataistransferredfromonepointtoanother.Expressedineither bits/secondorbytes/second.

DOUBLE FREQUENCY ENCODING

AnothernameforFMencoding.Thisisbecauseallpossibledatacombinationswill resultinonlytwopossibletemporaldisplacementsofadjacentdatabits,specifically “1F”and2F.”

E

EARLY WINDOW

Adatawindowthathasbeenintentionallyshiftedintimeinanearlydirection.

EMBEDDED SERVO

Aservotechniqueusedfortrackfollowing.Positioninformationisprerecorded betweendataareasinatracksothatadatahead,andproperadditionalcircuitry,can determinethedataheadlocationwithrespecttothecenterpositionofthetrack(or cylinder)inquestion.

ERASE

Aprocessbywhichasignalrecordedonamediumisremovedandthemediummade readyforrerecording.

ERROR CORRECTION CODE (ECC)

Amathematicalalgorithmthatcandetectandcorrecterrorsinadatafield.Thisis accomplishedwiththeaidofCheckBitsaddedtotherawdata.

ERROR FREE

Arecordingsurfacethathasnodefects.

ERROR RATE

Thenumberoferrors(typemustbespecified)thatoccurinaspecifiednumberofbits read.

ERROR RECOVERY PROCEDURE

Theprocessthatoccursinresponsetoadataerror.InadrivewithoutECC,this wouldincludere-calibrationandre-seekingtothespecifiedtrackandrereadingthe specifieddata.

EXTRA PULSE

Termusedinsurfacecertification.Itiswhenafluxfielddiscontinuityremainsafterthe recordingsurfaceiserased,therebyproducinganelectricaloutputofareadhead passingovertheareawiththediscontinuity.Anextrapulseoccurswhentheelectrical outputislargerthanaspecifiedthreshold.

F

FEEDBACK

Inaclosed-loopsystem,theoutputsignal(fromtheservohead)isusedtomodifythe inputsignal(tothepositioner).

FETCH

Areadoperationanditsrelateddatatransferoperations.

GL – 2