Pressed CD are superior to CD-R in longevity.
CD-R recordings are designed to be permanent, but over time the dye's
physical characteristics may change, causing read errors and data loss.
Testing has demonstrated such degradation of some discs in as little as
18 months under normal storage conditions. (bad CD-R quality)
http://www.cdfreaks.com/news/CD-Recordable-discs-unreadable-in-less-than-two-years.html
DVD-R are less resistant than CD-R
The problem is to determine when you should renew your DVD-R. Having 2
copies is useless, as they are going to age simultaneously.
Some software improves your chance of recovering your data by burning
same data at different place on your DVD-R (you can put less data on 1
DVD-R)
On servers we trust magnetic tape, then multiple hard drives system,
then optical media (CD, DVD...)
http://en.wikipedia.org/wiki/Computer_data_storage
Xavier.
[EMAIL PROTECTED] a écrit :
> I have music CDs that are over twenty years old and still play well. I don't
> know if that's the same as a data CD. I have checked some of my earliest
> picture file DVDs, which are about five years old. Thus far, they're all
> fine. Is there a technical explanation for why these storage devices wouldn't
> be semi permanent? The files can't fade or walk away. At least not so far as
> I know.
> Paul
> -------------- Original message ----------------------
> From: Xavier Cremaschi <[EMAIL PROTECTED]>
>
>> Be careful, a cd lives for 10 years, a dvd for less than that (5 maybe)
>>
>> http://le-gall.net/sylvain+violaine/blog/index.php?2007/10/21/31-reading-a-10-ye
>> ars-old-cd-r
>>
>> [EMAIL PROTECTED] a écrit :
>>
>>> I do back up to DVD. I have several hundred in storage. My five drives give
>>> me
>>>
>> over two terabytes of space. They're about 70% full now. I'll add another
>> 500
>> gigs soon. I keep very few backups on drives, save temporary backups for
>> important jobs. The general backups are almost exclusively on DVD.
>>
>>> Paul
>>> -------------- Original message ----------------------
>>> From: [EMAIL PROTECTED] (Ralf R. Radermacher)
>>>
>>>
>>>> <[EMAIL PROTECTED]> wrote:
>>>>
>>>>
>>>>
>>>>> I do work on a Mac, but I doubt that makes a difference.
>>>>>
>>>>>
>>>> So do I.
>>>>
>>>> If you get along with 5 hard drives, you just don't have enough picture
>>>> files. :-)
>>>>
>>>> The problem some of us are having is that we have so much stuff that we
>>>> need to keep some of it (the vast majority in my case) on external
>>>> drives which aren't connected all the time or on removeable media.
>>>>
>>>> Ralf
>>>>
>>>> --
>>>> Ralf R. Radermacher - DL9KCG - Köln/Cologne, Germany
>>>> private homepage: http://www.fotoralf.de
>>>> manual cameras and photo galleries - updated Jan. 10, 2005
>>>> Contarex - Kiev 60 - Horizon 202 - P6 mount lenses
>>>>
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>>>
>>>
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