Re: Blue Ray BD-R capacity? - Dual Layer Reliability/Shelf Life? by Cale Mooth on Apr 9, 2008 at 8:58:42 pm
Looking at some of the early PC World reviews, they're getting about 22-22.5GB on a disk.
Dual and single layer media shouldn't make a difference in archival life. And they should surely last another 10 years when the next great optical disc format materializes. The only thing to worry about now is that not all BD-R drives support dual-layer discs.
Dual Layer - Thanks Cale! by Mitch Sink on Apr 9, 2008 at 9:22:45 pm
[Cale Mooth]"Looking at some of the early PC World reviews, they're getting about 22-22.5GB on a disk."
Hi Cale,
I am going to have some 30 minute SD in Sheer which I plan to archive on Blu-Ray. The 30 minute programs will be about 22.5 GB so it looks like I will be right on the edge with of single layer with some of them.
I have heard of people having problems with DVD reliability, usually with poor quality discs. Here is some information on some of the relevant factors and choosing discs for archiving:
http://adterrasperaspera.com/blog/2006/10/30/how-to-choose-cddvd-archival-m... Why archival media is hard to produce
Unlike pressed CDs/DVDs, ‘burnt’ CDs/DVDs can eventually ‘fade’, due to five things that effect the quality of CD media: Sealing method, reflective layer, organic dye makeup, where it was manufactured, and your storage practices (please keep all media out of direct sunlight, in a nice cool dry dark place, in acid-free plastic containers; this will triple the lifetime of any media)
Assuming that the protective seal and reflective layer are manufactured correctly, the next issue is the organic dye. The first organic dyes, designed by Taiyo Yuden, were Cyanine-based and, under normal conditions, had a shelf life of around ten years; simply, that was simply unacceptable for archive discs. Taiyo Yuden, Mitsubishi Chemicals, Mitsui Co., and Ciba Specialty Chemicals spent the next ten years trying to produce the best organic dyes, eventually reaching archive-quality CD media.
DVDs also use similar dyes, however manufacturers have intentionally kept what dyes they use a secret (instead of a feature in their marketing of the media), and all blank DVDs are intentionally the same color (as different dyes on CDs make blanks different colors, however, it is not indicative of what dye is used due to some manufacturers using different colored silver alloys and non-reactive additives in the dye).
I wondered if Dual Layer would be more likely to have problems as it seems like that is pushing the envelope even further. Glad to hear you don't think it will be an issue.
This refers to DVDs specifically, but they regard single layer and dual layer as the same.
Blu-ray is very new, so quality is still unknown, but I would feel better buying Blu-ray discs from manufacturers that are known for producing other disc media of high quality.
Cale
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