October 14, 2004NIST/GIPWoG - Fred Byers1 Reducing Uncertainty National Institute of Standards and Technology (NIST) Information Technology Laboratory Information Access Division Fred Byers NIST 100 Bureau Drive, Stop 8940 Gaithersburg, MD

October 14, 2004NIST/GIPWoG - Fred Byers2 Topics Consumer View Life Expectancy Test Issues Alternatives Benefits

October 14, 2004NIST/GIPWoG - Fred Byers3 Manufacturers vs. Headlines Manufacturers Life Expectancy Best Case –~ 100 – 300 years CD-Rs –~ 60 – 100+ years DVD-Rs Headlines Life Expectancy Worst Case –CDs fail in short time frame –2 -10 years failure –“CD Rot” Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers4 Most Commonly Asked Question: How long will my (recordable) disc last? (CD-R, DVD-R, DVD+R) Answer:  It depends on: Care and handling –Physical handling –Environmental influences Initial recording quality –Condition of disc before recording –Quality of burn (depends on disc and burner) Disc construction –Materials –Manufacturing process Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers5 More Consumer Questions : Should I trust my digital content for long-term storage using these discs? Which disc should I buy? What is the minimum number of years I can expect? Does price make a difference? Does brand make a difference? What should I look for in a disc? Does the recorder make a difference? These above points are not unique to optical discs. Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers6 What can the user control?  Proper handling –No scratches, etc.  Proper storage –Controlled at recommended storage conditions ? Initial recording quality –Good disc – clean, defect free, good recorder  Disc construction –Dependant on manufacturer Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers7 - Relatively New - Long-Term Quality Discs Archive, or long-term labeled discs are available from some manufacturers What does it mean? –How are they different from regular discs? –How many years will they last? Longer LE? –How does manufacturer A compare to manufacturer B? –How are they determined to be longer lasting? Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers8 Disc-Test Proposal A test to measure for minimum longevity expectation A test that can be performed in a reasonable time for manufacturers An indicator to consumers about minimum quality A minimum longevity that consumers can use for planning Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers9 Why Variation in life expectancy among discs –Quality differences between brands –Quality differences within brands General claims of up to 100 years LE (DVD  R) –Actual could be as low as 30 years in normal ambient room conditions –Some anecdotal stories conflicting with general claims User confidence/uncertainty/awareness –Consumer expectations - uncertain or unrealistic –Planning under uncertainty – refreshing, sampling and migration Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers10 PIE from Metal-Halide Light PIE from High T and RH DVD-R Accelerated Aging Comparison Examples Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers11 Life Expectancy (LE) Test Standards Existing LE Test Method Standards CD-ROM –ISO 18925:2002, AES , ANSI/NAPM IT9.21 CD-R –ISO 18927:2002, AES Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers12 LE Testing Issues Time duration – Typically one to two years – Time to market Capability – Equipment – Space – Expertise Cost – Labor – Contract out Existing LE Test Followed? No Standard DVD Test –No Standard LE Test for DVD yet –NIST is proposing a DVD procedure following the CD Standard No Standard “archive quality” test methodology –NIST proposing a model LE Issues

October 14, 2004NIST/GIPWoG - Fred Byers13 LE - Accelerated Aging Times Stress Test-Set Stressed at (T inc, RH inc ) Incubation duration Minimum total time Specimen quantity 180 ºC, 85 %500 h2000 h ºC, 70 %500 h2000 h ºC, 55 %500 h2000 h ºC, 85 %750 h3000 h ºC, 85 %1000 h4000 h30 13,000 h total 80 total LE Issues

October 14, 2004NIST/GIPWoG - Fred Byers14 Incubation + Testing Time No. of Chambers Incubation time No. of weeks Testing time (2 analyzers) Total Time 113,000 hrs78 wks6 wks84 wks 27,000 hrs42 wks6 wks48 wks 35,000 hrs30 wks6 wks36 wks 44,000 hrs24 wks6 wks30 wks LE Issues

October 14, 2004NIST/GIPWoG - Fred Byers15 Alternatives to the Existing LE Test (to save time and cost) Shorten the LE Test –Less expensive but –Less accurate Initial Error Rate Test –Measures initial quality of data on disc but –Does not account for disc degradation rate –Does not indicate life expectancy Target Test - “Archival”, or “Longevity” or “Grade” –Longevity specific, i.e.: minimum number of years expected –Not a test to determine total disc LE Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers16 Alternatives Continued Shorten the LE test –Creates higher uncertainty for total disc LE measurement But –Uncertainty level should still be acceptable for a lower limit Consider error increase-rate –> x = fail Consider initial measurement? –BLER-max > x = not acceptable –Reflectance < x = not acceptable Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers17 Another Approach Don’t calculate for LE (T 50 ) but make it a known lower limit. Example: Make LE (or T 50 ) = 50 years = lower limit. (At storage conditions 20ºC, 50%RH) Determine from stress tests if disc will perform beyond the lower limit. Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers18 Existing Equation from CD Standard Existing equation from CD-R Standard: T 50 = Ae  H/kT e (B)RH or lnT 50 = lnA +  H/kT + (B)RH T 50 = Time duration for median disc in a test-set to reach BLER-max (220). A,  H and B determines the rate at which median disc reaches maximum allowed errors (220). Normally we derive A,  H and B from test data, then calculate for T 50. Constants: k T (Temperature) RH Derive from test data: A  H B Calculate: T 50 (Time) Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers19 Alternative Use of Existing Equation Using T 50 = Ae  H/kT e (B)RH or lnT 50 = lnA +  H/kT + (B)RH Instead of calculating for T 50, make T 50 known. For example: T years (disc reaches BLER-max of 220 in 50 years at a given T and RH) Find A and combined e coefficients (  H and B) for T 50 = 50yrs Constants: k T (Temperature) RH T 50 Derive from T 50 = 50: A  H B Do not Calculate T 50 : Make T 50 = 50years Use: lnT 50 = lnA +  H/kT+ (B)RH lnT 50 = at 20ºC, 50%RH Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers20 First Stress Test Set 500 hour intervals x 4 80  C, 85%RH

October 14, 2004NIST/GIPWoG - Fred Byers21 Targeted Time Periods? (“Sunscreen” Approach) Can have more than one target or establish only one target. –Total disc LE is unknown (not necessary) –> 30 yrs –> 50 yrs –> 75 yrs –> 100 yrs A test for one targeted minimum longevity time period –50 year example –Discs are expected to extrapolate to beyond the lower-limit threshold. –Error rate increases less than an established maximum acceptability Alternatives

October 14, 2004NIST/GIPWoG - Fred Byers22 What will this do for the Consumer? Consumer Indecision Revisited : Should I trust my digital content for long-term storage using these discs? (Properly tested discs, yes) Which disc should I buy? (Tested discs) What is the minimum number of years that I can expect? (As labeled) Will price make a difference? (Maybe) Will brand make a difference? (Maybe: quality control consistency) What should I look for in a disc? (Label showing that the disc batch has passed the test) Does the recorder make a difference? (Maybe, same as before) Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers23 Consumer/Industry Benefits Consumer –Consumer uncertainty reduced –More informed choice for consumer –Increase consumer confidence –More realistic consumer expectation –Consumer purchasing can be based on needs or migration plans Industry –Industry-wide standard test –Self-test or third party –Time to market –Testing cost (compared to existing LE testing) –Pricing (cost recovery for implementing new procedure) Benefits

October 14, 2004NIST/GIPWoG - Fred Byers24 What Is Needed From You, The User Define what “archival” means to you or what length of time needed for long-term storage. What is the minimum length of time needed for a disc to last to satisfy your requirements? What is the ideal length of time? Will this make a difference in your purchasing decision? Will you look for these “labeled” discs for long-term storage applications instead of other discs? Consumer View

October 14, 2004NIST/GIPWoG - Fred Byers25 Other ideas Early warning indicator RFID

October 14, 2004NIST/GIPWoG - Fred Byers26 Early Warning Indicator Could also be called: –Error Alert –Check Disc A warning about error rates that are approaching BLER max or PIE max. –May also consider Burst errors Just a light as an indicator or a pop-up window Gives the actual number (good for initial error rate)

October 14, 2004NIST/GIPWoG - Fred Byers27 Thank you! NIST Information Access Division Information Technology Laboratory Digital Data Preservation Fred Byers, Oliver Slattery, Jian Zheng Care and Handling Guide

October 14, 2004NIST/GIPWoG - Fred Byers28 Second Stress Test Set 500 hour intervals x 4 LE Issues 80  C, 70%RH

October 14, 2004NIST/GIPWoG - Fred Byers29 Third Stress Test Set 500 hour intervals x 4 LE Issues 80  C, 55%RH

October 14, 2004NIST/GIPWoG - Fred Byers30 Fourth Stress Test Set 750 hour intervals x 4 LE Issues 70  C, 85%RH

October 14, 2004NIST/GIPWoG - Fred Byers31 Fifth Stress Test Set 1000 hour intervals x 4 LE Issues 60  C, 85%RH