The seismic industry requires huge amounts of storage of valuable data.

My small survey department (30 people) was Sun Microsystems' first on-line Terabyte facility in the UK, back in 1987 (made up of dozens and dozens of 5 and 10 Gb hard drives).

But for long-term storage, only certain media have been approved. Initially it was 9-track tapes (I still occasionally need to read some. In that case we "bake" them to stabilise the oxide. I get about 90% recovery from 25-30 year old tapes, IF they were a good brand). Then it became 3480 cartridges, then 3590, DLT and 3590 cartridges for archive storage.

The industry has NEVER allowed optical media for long-term archiving...we've always known it was unreliabe...as are the more compact 8mm and 4 mm cassete-type magnetic media such as Exabyte.

Even with the most rigorously tested cartridge media, we still tend to re-copy the data every 10 years or so onto fresh media. We're talking thousands of terabytes here. A single marine seismic line, perhaps acquired in an hour, can generate 300 Mb of data used just to compute positions of the hydrophones alone, with perhaps another 3 Gb of data recorded from the hydrophones themselves.

So if organisations for whom these quantities of data are critical and extremely valuable don't use optical media for long-term storage, preferring instead to spend orders of magnitude more money on more stable cartirdge media, that says something about its reliability, I think.