backups to cd and other disks and maintaining file attribs

[Jason Clinton]

hanasaki wrote:
 >>>  Subject: backups to cd and other disks and maintaining file attribs

Oh yes. I should also mention that RW-media of all types is little more 
than a film that changes its color under the write laser. Like film, 
there are a number of environmental conditions that can contribute the 
the media failing. I've heard as little as 3 - 5 years of shelf life is 
all you'll get out of the media.

On the other hand, MO and DVD-RAM are attractive options. MO media has a 
rare-mineral substrate in which the electron spin of the mollecules can 
only be altered if the media has first been heated by the write laser to 
an astronomical temperature. Essentially, the data is store magnetically 
and its guaranteed to not do any bitflipping because the conditions to 
allow that to occur would never occur naturally. I'm not sure what MO is 
rated for in terms of shelf life but it is high. A protective cartridge 
is also mandated.

DVD-RAM also has a substrate that's composed of some rare minerals -- 
the latest forms of DVD-RAM (5x) use bismuth coupled substrates. The 
write laser heats the localized area to 1,400F to change the reflective 
index to record a 1 bit. (4|9)00F is used to set it back to 0. These are 
changes that are much more substantive and thus, the shelf life here is 
approximately 30 years. Protective cartridge is optional.



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