Longevity of DVD-R and CD-R (Was MagTapes)

[Eric Smith]

Richard wrote:
>  4) All RW media (DVD-RW DVD+RW CD-RW) have poor archival life.
>    Think about it: with RW, instead of burning a pit in the data
>    layer, you are fooling around with glossy or matte finish
>    depending on how quickly a melted liquid re-freezes. Official
>    tests, and my own tests, show poor life. A little sunlight-UV
>    can erase it.

It was my understanding (perhaps wrong?) that RW media uses a phase
change to store the data, and that it takes significantly more energy
to induce the phase change than to induce a chemical change in dye
for write-once media.  That's why it can't be written as quickly.
If it really works that way, one would reasonably expect RW media to
have *better* longevity than write-once media.

So is my premise wrong?  Does rewritable media not use a phase change?
Or is the activation energy comparable or lower than that for write-once
media?

> My least favorite factory is CMC Magnetics

They seem to make about the worst CD media, so it's unsurprising
that they make poor DVD media.

> I think Pioneer and Verbatim buy their media from
> the good Japanese companies, Mitsubishi, Taiyo Yuden, and Mitsumi.

By "Mistumi" you must have meant "Mitsui"?  For CD media, Taiyo Yuden
and Mitsui are definitely the best.

> TDK seems to be only advertised brand that makes their own

I used to buy TDK CD-R media at Costco because it was made by
Taiyo-Yuden.  Then they switched to CMC Magnetics, and after
using one spindle of that (with >50% reject rate), I refuse to
ever buy media from them again.

I'm surprised that TDK would make their own DVD media when they don't
make their own CD-R media.  More likely they're contracting out
manufacture and getting the vendor to mark the metadata as TDK.

Eric