From: Patent Tactics, George Brock-Nannestad


Steve Smolian asked whether CD-Rs or DVD-Rs had the longer lifetime. This 
permits a different approach. If one really considers that one could settle 
for a storage capacity of a CD, then the much larger storage capacity of the 
DVD (8+ GB in two-layer) may be used for redundancy. Repeat the 700 MB over 
and over again is a primitive way, but it would permit retrieval of data, 
even if a radius range were splotched. More intelligent ways would probably 
permit a compromise, so that perhaps would go into 2 GB safely per DVD-R.

Kind regards,


--who believes that even gardeners go on strike sometimes

> On Tuesday, June 30, 2009 11:30 AM, Steven Smolian wrote:
> > Is there a reliable recordable DVD for long term storage, 
> > independently tested?
> >
> > How does this compare with the anticipated lifespan of 
> > gold-reflective CDs?
> On the near horizon there may be a new family of optical
> media that is mechanically etched directly into the media
> rather than "burned" into an organic dye.
> These new optical discs will require a special "etcher",
> but the etched disc will be playable in a standard CD,
> DVD or even Blu-Ray player.
> Estimated life spans could be on the order of millennia (far
> outliving the devices used to read the discs).
> I've heard from the manufacturer that they can etch a disc,
> place it in an autoclave (at temperatures high enough to
> curl a normal polycarbonate CD or DVD), remove the etched 
> disc from the autoclave, let the disc cool, and then read 
> it without difficulty.
> I hear these new "etched" optical discs are going into 
> beta test (blanks and etchers) later this year at a handful
> of select sites.  I hope to visit their manufacturing plant
> later this summer.
> If you need something equally archival right now, I've had
> chemically etched glass CDs (using a photolithographic 
> process) produced for my clients.  These are not inexpensive,
> on the order of 10-15x the cost of a MAM-A disc.  Aside from 
> the fragility of glass, these chemically etched glass discs 
> probably have lifespans on the order of millennia.  If the
> reflective layer ever fails, you simply recoat the disc.
> There are no layers to delaminate.  And they are highly
> scratch resistant.  Of course, once again the media will 
> outlive the equipment to read the media.
> Eric Jacobs
> The Audio Archive, Inc.
> tel: 408.221.2128
> fax: 408.549.9867
> mailto:[log in to unmask]
> Disc and Tape Audio Transfer Services and Preservation Consulting