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Data reliability on optical Data reliability on optical discsdiscs
Mladen TušekMladen TušekFilozofski fakultet, Ivana Lučića 3, ZagrebFilozofski fakultet, Ivana Lučića 3, Zagreb
Hrvatska [email protected]@yahoo.com
IntroductionIntroduction
Optical discs suitable for preserving data:
• CD 650 or 700 MB• DVD 4,7 or 9 GB• HD DVD 15 or 30 GB• Blu-Ray 25 or 50 GB
Long term data Long term data preservation on optical preservation on optical
discsdiscs• Physical damage• Chemical damage
-chemical layer “Phthalocyanine”
-reflexive gold layer
IdentificationIdentification of media of media
• Identification of disc manufacturer• Identification of chemical layer• Other relevant information about optical disc
AnalysisAnalysis and and data recoverydata recovery
• Disc reading speed as indication of data status on discs chemical layer
• Aging of chemical layer causing data loss on all optical discs of the same manufacturer
• Unequal quality of chemical layer causes data loss on one or more optical discs
ConclusionConclusion
• Using quality discs, two of them with different chemical layer and manufacturer
• Parallel data writing on two computers with two different data recorders (different manufacturers: Plextor and Pioneer, for example).
• Low speed recording (4x) and mandatory data verification after recording
• After data recording test readability of recorded disc in different optical devices
• After one recording session and before erasing source data make readability test
• During archiving process in regular intervals (every 6 months) check readability using random method
• In case of problem use specialized applications and copy content of optical disc before irreversible data loss occur
Thank YouThank You