[Coco] DVD Archival - Was Re: Roger Taylors Coco DVD

[Chris Lomont]

DVD archive quality is NOT quite that cut and dried, though. 70+ years 
assumes the DVD has very special storage conditions, is not being used, 
and you are very lucky on many fronts. A slightly older NIST study 
(http://www.itl.nist.gov/iad/894.05/docs/StabilityStudy.pdf) found that 
although some DVD versions may last tens of years, they also found 
considerable variation among manufacturers and even found some disks may 
fail in as short a time as a *few weeks* if they are in sunlight (which 
eats the dyes in recordable DVDs/CDs), not to mention the variation on 
DVD and CD burners, writing speed, etc.

So please don't buy into the marketing claims that DVDs or CDs are good 
for archival backup. I know a few photographers that have made this 
mistake only to find their photos eaten after only a few years, even 
using name brand backups.

Thus the best backup is multiple backups, with frequent comparisons to 
remove and replace rotting data as soon as possible. For my work I use 
an offsite RAID system, and that is even backed up to single drives from 
time to time.

Gene Heskett wrote:
> On Monday 06 August 2007, Kevin Diggs wrote:
>   
>> Hex Star wrote:
>>     
>>> How will we know when it's ready for purchase? As I've said before and
>>> will say again, if Roger  does not wish for the dvd package to be shared
>>> via internet download then I will not put the dvd pack on my server and
>>> instead will use it for my own personal hobby interests as well as make a
>>> backup image of the dvd package on a internal offline backup harddrive. At
>>> no time will the dvd ever be shared online if that is Roger's wish.
>>>
>>> --
>>>       
>> 	Can someone explain to me why you need to "make a backup image of the
>> dvd package on a internal offline backup harddrive"? Isn't a DVD going
>> to be far more reliable than some hard drive? Hard drive failures? User
>> errors (i.e. rm -f)?
>>     
>
> It depends on the dvd Kevin.  dvd+r's have an estimated life of 70 years, 
> dvd-r's as little as 18 months, so if you want archival storage, you put it 
> on dvd+r's.
>
>   


-- 
-------------------------
Chris Lomont
http://www.lomont.org