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Re: DATs, Was Re: arsclist Duplicating casette tapes

From: Patent Tactics, George Brock-Nannestad

This is in response to various input, partly quoted at the end.

During the Joint Technical Symposium Paris 2000, Bernd Hänsch 
presented counter-intuitive results that concluded that DAT was in 
practice more stable than CD-R. It turned out that DAT had 
improved and changed little, whereas CD-R had developed quite a 
lot and deteriorated. Read all about it in:

"Image and Sound Archiving and Access: the Challenges of the 3rd 
Millenium - Proceedings of the Joint Technical Symposium Paris 
2000", Eds. Michelle Aubert and Richard Billeaud, CNC, Paris May 
2000, pp. 94-103 (including discussion).

During the AES 20th International Conference in October, 2001, 
information was presented which give grave warnings about CD-R. 
The paper by Stanislav Psohlavec was only referred to and 
recommended, but it is printed in "Practical Experience with Long-
Term Archiving of Data on CD-R", in: "The Proceedings of the AES 
20th International Conference 2001 October 5-7 Budapest, Hungary 
- Archiving, Restoration, and New Methods of Recording", Co-
chairs Éva Arató-Borsi and Dietrich Schüller, Audio Engineering 
Society 2001, pp. 15-17.

The paper by Drago Kunej on pp. 18-25 of the same publication 
"Instability and Vulnerability of CD-R Carriers to Sunlight" is a most 
practical and simple approach which is frighteningly realistic.

Based on a variety of information, including the papers introduced 
above, my advice to archives has gradually changed into something 
along the following lines: do indeed use CD-R, but do check 
regularly for quality of the content. Even simple BLER count 
statistics will tell you which CD-Rs will break down before you can 
reconstruct the content perfectly with the very good error correction 
that the system possesses. But it requires a routine and it may be 
costly, but you will actively preserve the data. 

Then as to storage and use of the CD-Rs: keep them in the dark, 
do not scratch, do not bend, break off any centre clip plastic parts 
you need in order to get the CD-Rs out of the Jewel Case (the 
original grey-black design never gave a problem, because you can 
push the fingers, but the types where it is all polystyrene integral 
with the case are terrible. Archives are always left with systems at 
the mercy of the manufacturers. And these days there is a veritable 
race to put as much on the CD-Rs as quickly as possible (24x is 

I am about to go back to R-DATs I made in 1995 (they were copied 
to CD-R in 1999), and if I have trouble, I will let you know. But I 
suspect that they will work fine.

> James Perrett wrote:
> > 
> > Language Laboratories and Archives wrote:
> > 
> > > Do you have any specifics or sources for the anecdotal reports? I
> > > am interested because we are doing our archiving to DAT--given
> > > that the shelf-life of CDs, and therefore, presumably, DVDs is
> > > really an unknown.
> > >
> > > Barbara (----- the originator of the thread)
> > 
> > I notice that
> > http://www.hp.com/products1/storage/products/automatedbackup/pdfs/au
> > toloaders/faqs/NIL002AQV.html#faq14 talks about a life of 10 years
> > for DDS DAT's. I have also seen this quoted on manufacturers DAT
> > tape specifications.

> Media Sciences tested helical scan 4 mm and 8 mm DAT tapes for several
> years. We noticed that repeated passes over the tape resulted in
> debris pileup and dropouts at the beginning and end of each pass.
> Heads attached to the rotating drum not only contact the tape but
> locally deform the tape in order to avoid high frequency gap losses.
> This would not be an issue for write-once archiving but is important
> if such tapes are rewritten.
> Jerry
> Media Sciences, Inc.

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