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D DataRecoveryGlossary
Database
acompilation
of
data
on
acomputer
drive
and
in
acompatible
format.
Thisdataisorganizedinawaythatitcanbeusedtoserveasinformationinitsfield
ofrelevance.Forexample,listofhotelsthathavevacanciesarethedatabasewhich
ispresentedtouserswhentheysearchforavailabilityofroomsinahotel.
Datasynchronizeraclocksignalthatissynchronouswithincomingfilesordatais
producedbyanelectroniccircuit,andthesignalisusedtodecodetheinformation
beingreceived.Thecircuititselfactsasasynchronizer;forexample,appsandmobile
phonesarekeptinsyncconstantlybytheelectroniccircuit.
Datatransferratethespeedatwhichelectronicdatastoredinonedevicetravels
toanotherdevicethroughsomeformofconnectivity.Itismeasuredinmegabitsor
megabytesofdatasentpersecond.Whensomedataistransferredwithinonehard
drive,itiscalleddatatransfertodisk,andtherateisexpressedasmegabitsper
second(Mbps).Whendataissentfromthebuffertothehostparty,itisexpressed
asmegabytespersecond(MBps).
Dedicatedservoadiskthatcontainsnootheruserrelateddataiskeptforthe
purposeofembeddingpositionsignalsthatcontainspecificinformation.This
informationis
used
to
position
the
read
or
write
heads.
A
servo
writer
is
used
to
writethesecontrolsignalswhichcannotbereproducedifanerroroccurs.
Dedicatedlandingzoneitistheareaoftheharddiskinsideacomputersystem
thathasnootherdatastoredonit.Thisareaisusedbytheread/writeheadswhen
thesystemisinactive.Thiszonealsomakessurethattheharddiskisnotphysically
damagedwhileitisbeinghandledbytheuserorwhendataisstoredonit.This
magnetizedareahasnocontactwiththesurroundingobjectstopreventdamage.
Defectfreewhenrecordingdevicesarereferredtousingthisterm,itmeansthat
theyhave
not
been
diagnosed
with
an
internal
or
apparent
defect
or
damage.
Defectmanagementwhenadefectisdetectedonarecordingdevice,suchasa
diskdrive,measurestoeliminatethosedefectsareknownasdefectmanagement.
Thisisdonebyeitherfixingthedefectorrenderingitinaccessiblesothatdata
storageonthedeviceisdonewithouthassle.Theinformationwrittenonthediskis
allocatedtoareasthatarefreeofdefectsorwillnotbeharmedbythehidden
corruptfiles.
Defragmentitisaprocessusedtodecreasetheamountoffragmentsproducedin
astorage
medium
such
as
ahard
drive.
This
process
is
complete
once
the
files
on
the
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storagedevicearereorganizedandtheleastnumberoffragmentsisreached.More
freespaceresultsinthediskoncethisisfollowedbycompactingthediskdrivein
ordertoinhibittheformationofmorefragments.Aswemountupdataonstorage
drives,theybecomeloadedwithnoncontiguousblocks.Onefilegetsscattered
acrossthewholedriveandperformanceofthesystembecomesweak.Thisisthe
pointwheredefragmentationhelps.Storagemediashouldundergothisprocessas
soonasfragmentationlevelreaches10%.
Desktopitisapersonalcomputersystemdesignedtofitthetopofadesk.Itcan
beusedinafixedlocationonly,unlikelaptopsthataremobiledevices.Modern
designsstanduprightonadeskandhavebeeninfusedwithlatestfeatures.
DifferentialSCSIitisanelectronicconfigurationthatmakesuseofduallinesfor
thetransferofdata.Itisusedfordevicesdemandinglongcableconnectionsofupto
25meters.
An
SCSI
connector
has
either
50
pins
(8
bit
system)
or
68
pins
(16
bit
system).
Directmemoryaccessthisfeaturehasbeenbuiltintomoderncomputersandisa
partoftechnologicalinnovationandprogress.Itinvolvesthetransferofdatatoor
fromthemainharddriveofacomputersystem,withoutinvolvingthecentral
processingunit(CPU)intheprocedure.Hardwaresubsystemsfoundinsidethe
computerareresponsibleforthisactionwherethemainsystemmemoryisaccessed
forsometask.TheCPUisnotkeptoccupied;hence,itperformsotherfunctionsatan
efficientandfasterrate.
Directoryitisthestorageunitforallthefilesinacomputersystemandalsoaidsin
thesearchprocesswhenyouarelookingforaparticularfileonthedisk.Allfilesand
foldersarearrangedinanorderthatyouprefer;suchasaccordingtodateof
modification,alphabeticalorder,sizeoffile,etc.
Diskhardwareinsidethecomputerthatstoresdata.Informationismappedonto
thediskandcanbeaccessedanytime.Ithasamagneticsurfaceusuallymadeof
aluminum.Thestoragecapacityofeachdriveisdifferent.
Diskcontrollertheelectroniccircuitinsideadiskthatenablescommunication
betweenthedriveandthecentralprocessingunit.Dataistransferredviasignals
convertedandtransmittedbythediskcontroller.
Diskdrivecontrolleracircuitboardonthefrontorbackofaharddiskthatacts
likealiaisonbetweentheCPUandthediskdrive.Itenablesthereadingandwriting
ofinformationordataontothediskbythecomputersystem.
DiskoperatingsystemDOSisaprogramorsoftwarethatorganizesandmanages
storage
media
on
the
computer
system.
The
information
or
files
inside
the
storage
devicesisorganizedandotherprocessesarealsocontrolledbythissoftware.
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Disktransferratethespeedatwhichinformationistransmittedtoorawayfroma
diskdrive.Thespeeddependsonthelocationofthetrack;datastoredontheouter
tracksofthediskistransferredatafasterrateascomparedtothatstoredonthe
innertracks.Therateisexpressedinbitsorbytespersecond.
Distributionchanneltheintermediarypartyinvolvedinthetransferofgoodsfrom
oneendtoanother.Theprocessinvolveselectronictransferviaelectronic
distributors.
DMAabbreviationfordirectmemoryaccess(explainedabove).Itisthefastestway
oftransferringdata.
DOSdiskoperatingsystem(explainedabove).UsuallyabbreviatedasMSDOS.
DRAM
it
stands
for
dynamic
random
access
memory.
Acts
as
the
main
memory
of
thecomputersystem.Anumberofcapacitorsgettogethertoformacircuitandeach
bitofinformationordataisstoredonaseparatecapacitor.
Driveraprogramthatcontrolsadeviceconnectedtoacomputer.Itisdependent
onhardwaretoperformitsfunctions.Thecommunicationbetweenthedeviceand
thecomputertakesplacethroughthedriver.
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