Thursday, August 13, 2015

Permanent Digital Data Storage: Tape, solid-state, and discs

Permanent Digital Data Storage: An Overview. Barry M. Lunt, Matthew R. Linford, and Robert C. Davis. Brigham Young University. ISOM Conference. Received PDF August 2015. [From author's  version; not yet available on line.]
     Research shows that digital storage, whether optical, solid state, or tape, can be permanent and could potentially last over 100,000 years if permanent materials are used. The failure mechanisms are well documented. Knowing what materials to use to eliminate the failure mechanisms is the key to permanent digital storage.

Computer data storage has always been ephemeral because of the emphasis on density and speed. There has been little interest in developing a permanent way to store digital data. The authors, an engineer, chemist, and physicist, believe "that the optimal storage media does not need to be refreshed nor stored in special conditions, and that a store-and-forget approach (like printing books and storing them on shelves) is best because it is the simplest."

Permanent Storage Options and approaches
  • Optical disks. The dominant failure mechanism is dye fading which can be removed by using permanent materials. 
    • The media they developed (M-Discs) make permanent physical and optical marks on a standard DVD or Blu-ray format disc.
    • Optical discs are a viable option for archival storage of large amounts of storage
    • This permanent format is essentially guaranteed for many decades or centuries to come
  • Hard disk drives are not permanent. The failure mechanisms, which are fairly well known, are predominantly mechanical. A materials approach cannot solve these problems.
  • Solid-state storage. A materials approach has produced storage elements capable of lasting as long as integrated circuits; the failure rate of such circuits is measured in Failure In Time, or about 114,155 years. This is a permanent form of preservation. Their research has solved the dominant failure mechanism of early permanent programmable solid state storage.
  • Permanent optical tape. Their materials-research shows that if correct materials are used, computer tape can also be permanent and the permanent tape would "match the density of LTO-5, allowing about 2 TB per cartridge. The price of the media should be equivalent to that of magnetic tape."
Optical discs, solid-state storage, and computer tape can all be made to store data permanently and last hundreds or thousands of years.

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