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Reducing Uncertainty

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 20899 Email: byers@nist.gov. Topics. Consumer View Life Expectancy Test Issues

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Reducing Uncertainty

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  1. Reducing Uncertainty National Institute of Standards and Technology (NIST) Information Technology Laboratory Information Access Division Fred ByersNIST100 Bureau Drive, Stop 8940 Gaithersburg, MD 20899 Email: byers@nist.gov NIST/GIPWoG - Fred Byers

  2. Topics • Consumer View • Life Expectancy Test Issues • Alternatives • Benefits NIST/GIPWoG - Fred Byers

  3. Consumer View 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” NIST/GIPWoG - Fred Byers

  4. Consumer View 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 NIST/GIPWoG - Fred Byers

  5. Consumer View 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. NIST/GIPWoG - Fred Byers

  6. Consumer View 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 NIST/GIPWoG - Fred Byers

  7. Consumer View - 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? NIST/GIPWoG - Fred Byers

  8. Consumer View 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 NIST/GIPWoG - Fred Byers

  9. Consumer View 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 NIST/GIPWoG - Fred Byers

  10. Consumer View DVD-R Accelerated Aging Comparison Examples PIE fromHigh T and RH PIE from Metal-Halide Light NIST/GIPWoG - Fred Byers

  11. Consumer View Life Expectancy (LE) Test Standards Existing LE Test Method Standards • CD-ROM • ISO 18925:2002, AES 28-1997, ANSI/NAPM IT9.21 • CD-R • ISO 18927:2002, AES 38-2000 NIST/GIPWoG - Fred Byers

  12. 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 LE Testing Issues NIST/GIPWoG - Fred Byers

  13. Stress Test-Set Stressed at (Tinc, RHinc) Incubation duration Minimum total time Specimenquantity 1 80 ºC, 85 % 500 h 2000 h 10 2 80 ºC, 70 % 500 h 2000 h 10 3 80 ºC, 55 % 500 h 2000 h 15 4 70 ºC, 85 % 750 h 3000 h 15 5 60 ºC, 85 % 1000 h 4000 h 30 13,000 h total 80 total LE Issues LE - Accelerated Aging Times NIST/GIPWoG - Fred Byers

  14. No. of Chambers Incubation time No. of weeks Testing time (2 analyzers) Total Time 1 13,000 hrs 78 wks 6 wks 84 wks 2 7,000 hrs 42 wks 6 wks 48 wks 3 5,000 hrs 30 wks 6 wks 36 wks 4 4,000 hrs 24 wks 6 wks 30 wks LE Issues Incubation + Testing Time NIST/GIPWoG - Fred Byers

  15. Alternatives 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 NIST/GIPWoG - Fred Byers

  16. Alternatives 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 NIST/GIPWoG - Fred Byers

  17. Alternatives Another Approach Don’t calculate for LE (T50) but make it a known lower limit. • Example: Make LE (or T50) = 50 years = lower limit. (At storage conditions 20ºC, 50%RH) Determine from stress tests if disc will perform beyond the lower limit. NIST/GIPWoG - Fred Byers

  18. Alternatives Existing Equation from CD Standard Existing equation from CD-R Standard: T50 = AeH/kTe(B)RH or lnT50 = lnA + H/kT + (B)RH T50 = 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 T50. NIST/GIPWoG - Fred Byers

  19. Alternatives Alternative Use of Existing Equation Using T50 = AeH/kTe(B)RH or lnT50 = lnA + H/kT + (B)RH • Instead of calculating for T50, make T50 known. • For example: T50 50 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 T50= 50yrs NIST/GIPWoG - Fred Byers

  20. First Stress Test Set500 hour intervals x 4 80C, 85%RH NIST/GIPWoG - Fred Byers

  21. Alternatives 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 NIST/GIPWoG - Fred Byers

  22. Consumer View 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) NIST/GIPWoG - Fred Byers

  23. Benefits 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) NIST/GIPWoG - Fred Byers

  24. Consumer View 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? NIST/GIPWoG - Fred Byers

  25. Other ideas • Early warning indicator • RFID NIST/GIPWoG - Fred Byers

  26. 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) NIST/GIPWoG - Fred Byers

  27. Thank you! NIST Information Access Division Information Technology Laboratory Digital Data Preservation Fred Byers, Oliver Slattery, Jian Zheng http://www.itl.nist.gov/div895/preservation/ Care and Handling Guide http://www.itl.nist.gov/div895/carefordisc/ NIST/GIPWoG - Fred Byers

  28. LE Issues Second Stress Test Set 500 hour intervals x 4 80C, 70%RH NIST/GIPWoG - Fred Byers

  29. LE Issues Third Stress Test Set500 hour intervals x 4 80C, 55%RH NIST/GIPWoG - Fred Byers

  30. LE Issues Fourth Stress Test Set 750 hour intervals x 4 70C, 85%RH NIST/GIPWoG - Fred Byers

  31. LE Issues Fifth Stress Test Set 1000 hour intervals x 4 60C, 85%RH NIST/GIPWoG - Fred Byers

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