Overview
ISO 18926:2012 provides a standardized method for estimating the life expectancy (LE) of information stored on rewritable and write-once magneto‑optical (MO) discs, considering only the effects of temperature and relative humidity (RH). The standard prescribes an accelerated aging test methodology and statistical analysis to predict long‑term data retrievability under defined storage conditions.
Key topics and technical requirements
- Scope and purpose
- Estimates LE of information stored on MO discs using accelerated temperature and RH stress tests.
- Produces a Standardized Life Expectancy (SLE): the predicted minimum life with 95% confidence for 95% of product stored at ≤ 23 °C and ≤ 50% RH.
- Test population and sampling
- Example plan uses a baseline sample (80 discs) divided into five stress groups; each disc is baseline tested for byte error rate (BER).
- Failure metric
- End-of-life (EOL) is defined as any loss of information or when average BER reaches 5.0 × 10^-4 (raw BER, with error correction off).
- Accelerated stress testing
- Discs are exposed to combinations of elevated temperature and RH in controlled test cells; specimens are periodically removed for BER measurement.
- Test plans combine practical sample allocation with statistical considerations (a “compromise” between traditional and statistically optimized plans).
- Data evaluation and models
- Per-stress lifetime data are fitted to a lognormal distribution.
- An Eyring acceleration model is used to relate life parameters to temperature and RH and to compute acceleration factors.
- Survivor analysis and regression produce lifetime distributions at standardized conditions.
- Measurement control
- Use ISO/IEC‑compatible drives; maintain a control disc and control charts for calibration and repeatability; correct for drive replacements.
- Assumptions
- Explicit assumptions include consistent failure mechanisms between accelerated and real conditions, BER linearity, and exclusion of reversible or external cartridge repair failures.
Practical applications and users
- Archives and cultural heritage institutions assessing long‑term preservation of magneto‑optical media.
- MO disc manufacturers and quality labs performing accelerated life testing and product qualification.
- IT asset managers and data recovery services estimating retention and refresh cycles for MO archives.
- Standards bodies and certification labs seeking reproducible, statistically sound LE estimates.
Related standards
Normative references include relevant ISO/IEC optical‑disc specifications used for test specimen definition, for example:
- ISO/IEC 10089, ISO/IEC 10090, and several ISO/IEC data interchange standards for 90 mm and 130 mm optical cartridges referenced in Clause 3.
ISO 18926:2012 also includes a ten‑step analysis outline (Annex A) and an example test plan and data analysis (Annex B) to aid implementation.
Keywords: ISO 18926:2012, magneto‑optical discs, MO discs, life expectancy, accelerated aging, temperature and humidity testing, byte error rate (BER), Eyring model, lognormal distribution.