On Fri, Dec 5, 2014 at 3:22 PM, Jack Coats <j...@coats.org> wrote: > > > Archival grade DVDs seem to have a 50 year 'sure life'. Magnetic media > (thinking tapes, 5 years, and reel tapes need to be 'exercised' annually to > extend their lives). 'Flash' media like memory sticks need to be > 'refreshed' by plugging in, even if data is not accessed, every year or two > before bit rot starts. > > > > All these are 'rules of thumb', and detailed or specific cases can and will > be quoted all over the place. When I worked for 'big oil' they had 50 > years of mag tapes (from the oil field seismic data) that was stored well > (exercised, in proper thermal environment, out of the weather, inside dust > cases, etc), but they found a 50% failure rate on data 5 years old and > older. They started just trashing their oldest seismic data. > Re-digitizing what they could (in some cases paper maps and logs were > better than digital data). This also made the data they had more useful. > But even that had its failings. Old data was not of high enough > resolution, or not measured in the spectra near what is currently used. So > much old seismic data was kept, but new was acquired (at high cost in many > cases) if possible to allow it to be useful in current exploration / > re-exploration of potential fields. >
I'd buy into disk inactive life of ~5 years, but LTO, Ultrium/IBM, and StorageTek have a published archival life of 30. I wouldn't count on that, per se, but certainly better than 5. The current technology of the tape substrate is quite amazing stuff. (think Kevlar with chemically welded Barium Ferrite magnetics). Yes, you still want to run periodic data verifies, but that is trivial with tape. IBM and Oracle/StorageTek are arguably better technologies than LTO in terms of durability, bit error rate, and density. LTO pretends to be catching up but it's own projections are falling pretty far behind unless something miraculous happens (don't count it out. We're hopeful, but realistically the other is still better) It sounds like they had a bad batch. What technology? It has come a long way even in the last couple of years. Plenty of companies recover from and still rely on tape, despite there being a few with a bad experience story. The story itself should be able to stand under scrutiny.
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