Re: Backup's to DVD
On Mon, 2014-03-17 at 17:51 +0200, Lars Noodén wrote:
> CDs and DVDs are physically different media than CD R and DVD R which
> are in turn different from CD RW and DVD RW. CDs will last a long time,
> as they have a layer of physically dented metal between slabs of
> plastic. But you can't press one yourself. For anecdotes, I have some
> pushing 30 years that play but I don't have MD5 checksums or anything to
> verify them.
>
> I've had some CD R last only a few years, starting from the date of
> manufacture not date of burn. The claim is 5 to 10 years, from date of
> manufacture, but I have yet to see a date on the packages. CD R uses a
> layer of dye which is then burned opaque. Those with higher quality
> dyes should last longer before data loss begins but the dyes oxidize
> over time and the rate depends on storage conditions and atmosphere.
> About the only advantage is that they cannot be re-written so, while
> they last, can serve as proof or evidence if a proper chain of custody
> is also maintained.
>
> CD RW is more complex having a phase-changing layer but max out at a
> theoretical 25 years under ideal storage and handling conditions,
> starting from quality manufacturing.
>
> See:
> http://www.clir.org/pubs/reports/pub121/sec4.html
>
> The longevity of flash is still a big unknown.
I made the best experiences with DVD-RAM. _When_ ever it was possible to
write to a DVD-RAM the data was safe, _but_ many DVD-RAMs were broken, I
payed a lot of money and the new once were already unusable, very often
neither Linux nor Windows was able to write data to DVD-RAM or it needed
hours just to write 1 KiB. And assumed you never ever will experience
writing issues, when using DVD-RAM, what are 4.7 GB good for? How often
will you split your tar files?
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