> -----Original Message----- > From: Association for Recorded Sound Discussion List > [mailto:[log in to unmask]] On Behalf Of George Brock-Nannestad > Sent: Tuesday, August 09, 2005 9:23 AM > To: [log in to unmask] > Subject: Re: [ARSCLIST] "Archival" DVD-R? > > From: Patent Tactics, George Brock-Nannestad > > Dear All (and this means the archiving community in its broadest sense), > > we are constantly bombarded with discussions of stability of Recordable > Optical Media, all very responsible and well-documented - I do not mind to > plug: > > > Joav Shdema: > > I have the following very current PDFs that deal with the subjects we > > discuss here: > > > > 1) Stability Comparison of Recordable Optical Media > > 2) Discs—A Study of Error Rates in Harsh Conditions > > 3) Care and Handling of CDs and DVDs —A Guide for Librarians and > > Archivists > > 4) DVD-ROM Drive Compatibility Test for DVD-R(General), DVD-RW, DVD+R, > > DVD+RW and DVD-RAM Discs > > ----- however, there are TWO trees that we need to bark up: > > - the tree that everybody is already dealing with > > - a stable CD or DVD is worthless if there is no equipment - drive - that > will read it. It does not matter if incompatibility between drive and > medium > only develops over time - the result is worthless in any case. > > ----- I have not seen any work reported on the long-term performance of > drives. To my knowledge there has been no accelerated aging of drives, no > continuous exercizing of drives until they break down (they do that to > IKEA > chairs, you know!) > > ----- there are several directions that product development takes. Early > generations are often very conservatively built, although virtually no > modern > equipment is built that needs maintenance, such as lubrication. Functional > units are replaced instead. Such conservatively built equipment is > expensive > in manufacture and in materials. For this reason, product development > intends > to replace ceramics, glass, and metal with plastic, and furthermore, more > and > more elements are made as complete castings, reducing assembly labor. > > ----- in a CD player, the original HeNe laser was quickly replaced by > laser > diodes. Glass lenses were replaced by plastic. I have not studied this in > detail, but there has been 25 years of development. > > ----- over the years, I must have disassembled about ten 3˝" floppy drives > (from the 720kb of the 1980s to 1.44 Mb of the 2000s), and the experience > has > not been happy. Just as an example: where the carriage for positioning of > the > reading head originally had brass (or bronze) bushes sliding on a polished > steel rod, that was replaced by plastic. Plastic may distort with time. > > ----- I have also disassembled a number of hard drives. Inside, everything > seems to be professional quality, no plastic, except where relevant for > weight and insulation, and precision ball bearings > > ----- in terms of DVD or CD drives: will the surface of the lens corrode > with > time and temperature? Will the material cloud? Will semi-reflecting > coatings > corrode? Will the carriage warp? Is there anything like "purple plague" > regarding integrated circuit termination anymore? Mothballing may not be > the > answer. > > ----- in conclusion I would like anybody who feels the urge to undertake > "stability tests" on optical disc media, to take the appropriate drives to > their local engineering department and to discuss the actual mechanical > and > electrical design. You will receive explanations for why a particular > material and configuration choice was made, and you will have a sparring > partner who will be able to predict performance under stress. > > ----- I fear that you will discover that you can only trust optical media > while the current generation of media and equipment is industrially > supported. Say five years, to be conservative. > > ----- I shall not respect future analyses of longevity, unless it is a > system > analysis, not a medium analysis. I know that it is much more expensive > than > leaving your discs out on your desk or in a car and monitoring the > progressive problems. But without a drive, all we preserve are mirrors > and/or > optical gratings. > > Kind regards, > > > George One key problem is that there are no standards for drives, only for media quality. What determines whether a drive is acceptable or not, other than complete loss of functionality? Jerry Media Sciences, Inc.