# Storage Medium Decay and Refresh Economics **Domain:** Digital Preservation / Continuity / Economics **Doc Type:** Preservation Method Node **Maturity:** Developed **Related:** [[wiki/Long-Term Digital Preservation|Long-Term Digital Preservation]], [[wiki/Continuity Provenance|Continuity Provenance]], [[wiki/Restoration Integrity|Restoration Integrity]] --- ## Definition **Storage medium decay and refresh economics** examines the recurring cost of keeping continuity records intact and usable as media fail, formats age, interfaces disappear and custodians change. ## Preservation Is a Process Multiple copies do not create permanence if they share the same failure domain, remain unchecked or cannot be interpreted. Long-term preservation requires fixity information, scheduled verification, repair from independent copies, replacement of failing media, format and platform monitoring, and tested recovery. The economic unit is therefore not a stored byte-year alone. It is a verified and recoverable state-year at a declared risk level. ## Cost Drivers - number, geographic separation and administrative independence of copies; - frequency and depth of fixity checking; - media service life and replacement cadence; - egress and migration charges; - retained software, schemas and execution environments; - staff time for exceptions and damaged objects; - proof that a restored state is authorized and semantically intact. Aggressive compression, deduplication or tiering can reduce cost while increasing correlated-loss or interpretability risk. The trade must be stated rather than hidden in a storage tariff. ## Planning Rule Budgets should include both routine refresh and exceptional migration. A reserve that funds media replacement but not provenance reconstruction, format conversion or validation may preserve bits while losing the ability to establish what those bits mean. ## Sources - [NDSA — Levels of Digital Preservation](https://www.ndsa.org/publications/levels-of-digital-preservation/) - [Library of Congress — Sustainability of Digital Formats](https://www.loc.gov/preservation/digital/formats/sustain/sustain.shtml) - [Library of Congress — Bit-level preservation and long-term usability](https://www.loc.gov/programs/digital-collections-management/digital-formats/bit-level-preservation-and-long-term-usability/) ## See Also [[wiki/Cost of a Continuant|Cost of a Continuant]] · [[wiki/Adversarial Provenance|Adversarial Provenance]] · [[wiki/Forensic Identity Attestation|Forensic Identity Attestation]] · [[wiki/Deep-Time Stewardship|Deep-Time Stewardship]]