R C-R wrote:
According to this FAQ published by the U.S. Federal National Archives, conventional burned optical discs have an archival shelf life of only 2-5 years
That link is superficial info at very best for a newbie.
The life of junk DVD blank media is a known entity, of course.
That link doesnt even mention how important DVD+R over DVD-R
Obviously I dont really care if it lasts 70 or 100 years, I wont be around, LoL
See here about the technology.
http://www.prweb.com/releases/2013/5/prweb10786336.htm
If governments acknowledge them and professional labs as "100+ year disks" , I do as well.
At 20% more than cheap consumer grade DVD blanks, its a no-brainer.
Also having burned many 1000s of DVD blanks, I know these disks have a very very low reject rate too.
We both know the nature of HD and server farms. CHEAP GOOD long-term optical storage is this, and ONLY this.
I use the same ones the pros are using Taiyo Yuden (JVC). Oddly, these professional DVD blank media are only 20% more than the cheap junk. been using them for years.
Point is junk DVD blanks are rated for 10 or so years, these special professional disks are not disputed to last "less than 60+ years"
Outside of stone carvings or copper plates, OR microfilm (lol)........the LONGEST CHEAP storage are "century DVD blank media"
Global governments are using them, and those who need hard and fast long term storage.
Manufactured using proprietary, unique dual reflective layers, these discs maximize both compatibility and longevity. To further extend media life, UltraLife™ Gold Archival Grade DVD-R’s contain a hard coating on the recording side to protect surface from scratches. In proper environmental conditions, these discs are designed to last up to 100 years.
The specifications refer to “dual reflective layer technology” – is this a Dual Layer DVD (DVD-R DL)?No. In terms of storage capacity, the UltraLife™ Gold Archival Grade DVD-R discs are single layer discs with a 4.7GB storage capacity.
Why 2 layers? What purpose does each layer serve?
The highly reflective silver layer allows the Ultra-Life DVD-R to look like a standard silver disc to DVD drives and burners, providing a low initial error rate and the same drive read/write compatibility as standard silver-only discs. The gold reflective layer, naturally resistant to corrosion, prevents oxygen from corroding the silver reflective layer, a common factor in limiting the life of DVD media.
What is AZO™ Technology?
AZO™ recording dye is a patented technology, which provides the highest level of read/write performance, reliability and archival life for your DVD Recordable media.
Can I record over data on an UltraLife™ Gold DVD-R?
No. Like other DVD Recordable media, UltaLife™ Gold DVD-R’s are single layer DVD discs designed for one-time recording.
Use DVD+R for your archives, not DVD-R
As to the type of professional DVD blank media: DVD-R is inferior for data preservation for several reasons: error correction, wobble tracking, and writing method. For a DVD to track where it is on the disc, it uses three things: the ‘wobble’ of the data track to tell where it is in the track, the position of the track to tell where it is on the disc, and some additional information where on the disc to tell where the track begins and ends. On –R media, the ATIP is stored as a frequency modulation in the wobble itself; since the wobble changes subtly to encode data, it is impossible to use with the small size of tracks DVD requires, as electric noise in the laser pickup and wobbles introduced by the electric motor spinning the disc, these could easily be read as frequency changes in the real track itself.
On DVD-R this problem had been attempted to be solved by ‘pre-pits’ where spikes in the amplitude of the wobble appear due to pits fully out of phase with the rest of the track (between two spirals of the track, where there is no data). This can be viewed as a simple improvement over CD-R as it makes it easier to track the wobble. This method has one flaw: due to electric noise in the laser pickup, it would be very easy to miss the pre-pit (or read one that wasn’t actually there) if the disc were damaged or spun at fast speeds. DVD-R traded hard to track frequency changes for hard to read wobble-encoded data.
On a DVD+R there is a better write method. Instead of changing the frequency of the wobble, or causing amplitude spikes in the wobble, they use complete phase changes. Where DVD-R’s methods make you choose between either easy wobble tracking or easy ATIP reading, DVD+R method makes it very easy to track the wobble, and also very easy to encode data into the wobble. DVD+R method is called ADIP (Address In Pre-groove).
Now, the third item on the list: how DVD+R discs burn better. ATIP/pre-pit/ADIP stores information about optimum power control settings. DVD-R basically fails on all three accounts because DVD+R simply includes far more information about the media in the ADIP data than DVD-R does in it’s pre-pit data. DVD+R includes four optimum profiles, one for four major burning speeds. Each of these profiles includes optimum power output based on laser wavelength, more precise laser power settings, and other additional information. With this information, any DVD+R burner can far more optimize its burning strategy to fit the media than it can with DVD-R, thereby providing better burns.
DVD+R also gives four times more scratch space for the drive to calibrate the laser on; more space can only improve the calibration quality. So DVD+R media exists to simply produce better burns and protect your data better, which when it comes to data hub archiving is of vital importance.
Of course there are other options
Paper 1000 years
copper/gold many thousands of years
stone million years (lol)
optical 10 years junk DVD... 100+ years metal compound-layer professional media
ferromagnetic (HD, TAPE) 3 to 30 years (commercial tape) (5-15 years for HD)
carborundum just invented, rated for 1 million years i.e. "sapphire drive"
(humor)
😊
