[time-nuts] While we're discussing backups...

Rex rexa at sonic.net
Wed Aug 27 05:01:42 UTC 2008


Neon John wrote:
> This is one of those areas that sink my confidence in predictive modeling and
> accelerated aging - if it could go any lower.
>
> My collection of data CDs, mostly digitized vinyl music and cassette-based
> audio books plus various specialized backup, number in the thousands, many
> over 10 years old.  I've yet to have that first one refuse to read, at least
> not any that didn't have physical damage.
>
> A couple of years ago I started moving to DVD data storage. No problems there
> either.  One rather extreme experience makes me think that all this stuff
> about aging is bunk.
>
>   
In general I agree with you but I have one case where discs became 
trash. It must have been from a problem in the manufacture.

I bought a couple recorded video DVDs from a small vendor. I'm not sure 
if they were burned, but I suspect they were. (As opposed to pressed - 
or what ever the right term is for the high volume manufacture method.)

They were fine when I played them randomly over the first several 
months. Then I lost interest and didn't try to play them again for at 
least a year, maybe a couple years. When I finally tried again they were 
useless. The inner shiny data surface had turned dull brown; more-so at 
the edges, but all of the two disks were unreadable.

So I know of at least one case where (I assume) some problem in the 
manufacturing process left these disks with a very short lifetime. These 
were not backups, not critical and no big loss, but the moral, I guess, 
is don't buy cheap no-name media for your backups. I believe there is an 
archival grade for DVDs and CDs. It might be worth using if the data is 
important to you and you expect to keep it on this media for a long 
time. Checking the backups periodically for signs of degradation is not 
a bad idea, unless the backups are only needed over a short period. This 
monitoring has been mentioned before, but requires the same kind of 
discipline needed as to make the backups in the first place.







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