On Fri, 2005-08-05 at 14:42 -0400, Peter Arremann wrote:
Hmm - MO needs a magnetic read head... I guess the technology you guys mean is PD as the base for DVD-+RW...
DVD-RW and DVD+RW are Phase Change, not Phase Dual IIRC. DVD-RAM, like PD-CD before it, is a MO variant called Phase Dual.
Phase Change media (no matter what kind) do have a high error rate... MO media do not.
Actually, MO can without write-after-verify correction. But yes, I oversimplified by referring to everything as MO. Sorry about that.
The biggest customer for those is the US government... it is common for a MO disk to have a 40+ year warrenty.
Typical expected lifetime is 30+ years, although that assumes you have other mitigating features (e.g., cartridge).
DVD-RAM is just the DVD Consortium's standard for rewritable. It was introduced early on because it was inexpensive, and created a real standard for optical archiving in a sea of proprietary MO formats.
DVD-RW was more of a consumer answer to DVD+RW.
BTW, from my understanding, DVD+R is more of a WORM implementation of DVD+RW, than a single groove record like CD-R and DVD-R.