Re: CDs, was DATs, Was Re: arsclist Duplicating casette tapes

[Jerome Hartke <jhartke@xxxxxxxxxxxx>]

Interesting comments. For CD-R test results see our web page at
http://www.mscience.com/longev.html

Results indicate "CD-R discs are capable of excellent longevity, but
achieving that potential requires diligence by both manufacturers and
users. Manufacturers claims may be valid, or may be based upon flawed or
non-existent data. Proper end-of-life indicators must be used to
estimate longevity. This study has shown that BLER is not a universal
indicator of media life, although most published longevity estimates
have utilized BLER as the sole end-of-life indicator."

In general, initial as-recorded quality and subsequent handling and
storage are the major controlling factors for CD-R discs, as they are
for all mass storage products.

Regarding effects of sunlight, yes it can degrade CD-R discs, but try
leaving tape under the same conditions.

Also, do not break the center holding fixture of jewel cases. This
fixture enhances longevity by suspending the disc and preventing either
surfaces or rims from touching the case.

Jerry
Media Sciences, Inc.

Steven Smolian wrote:
> 
> George, did any of these tests disclose what surface material was used for
> the CDs?
> 
> Steve Smolian
> 
> ----- Original Message -----
> From: "George Brock-Nannestad" <pattac@xxxxxxxx>
> To: <ARSCLIST@xxxxxxxxxxxxxxxx>
> Sent: Friday, August 09, 2002 12:49 PM
> Subject: 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
> > old!).
> >
> > 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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> > Copyright of individual posting is owned by the author of the posting and
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> > from the author of the post.
> >
> 
> -
> For subscription instructions, see the ARSC home page
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