Re: arsclist cd roms - which are closest to archival quality?

["George Brock-Nannestad" <pattac@xxxxxxxx>]

Date sent:      	Sun, 17 Jun 2001 04:56:24 -0500 (EST)
From:           	"M. Sam Cronk" <scronk@xxxxxxxxxxx>
To:             	ARSCLIST@xxxxxxxxxxxxxxxx
Subject:        	arsclist cd roms - which are closest to archival quality?
Send reply to:  	ARSCLIST@xxxxxxxxxxxxxxxx

Dear Sam,

I am certain that the question has been asked many times, but the 
answer keeps changing in dependence on what the suppliers will 
provide us with.

> 
> I apologize in advance if this question has been asked many times. 
> I'm working for a small but dynamic archives.  We create both analog
> and digital "archival"  copies of original recordings to
> preserve/archive them and make their contents available for multiple
> use by scholars and the communities with whom we work. 
> 
----- Well, it would be interesting to be told what you consider to be 
archival, i.e.  what you mean by the word "archival". Also, it would 
be of general interest to learn what kind of analog archival copies 
you make and on which equipment and carriers.

> My question: which cd rom "standards" are closest to archival quality?
> PhthaloCyanine gold-reflective surface?  Are those with blue-dye
> reflective surface now comparable? We need to make a rather large
> purchase and a good long term decision.  Of course, we are not relying
> solely on cd r technology to back up/store our resources.

----- One thing that must be hammered home is that today digital 
does not in itself mean "archival". It is not the medium that is 
digital, it is the system comprising the replay equipment (provided 
we say "digitise now, replay later)". Going digital is a certain 
request in a number of years' time for transfer from the present 
medium to a different medium, going from one coding system to 
another (all of which will hopefully be completely transparent, i.e. 
there will be no difference between the signal obtained during 
replay on today's equipment and the signal obtained by replaying 
the transferred digital information on future equipment). 

It is *only* through the unending transfer that the archival quality is 
obtained. The situation that we had in analog, that it would be 
possible to find a stash after 50 years of negligence and to replay 
the recordings is quite unlikely once the transfer to digital has been 
made. I consider that to be an irreversible coding that can only be 
made useful if it is constantly nursed. If the nursing can be 
performed automatically it is much cheaper than labor, but the 
initial investment is heavy. Miss a generation of transfer, and 
everything is lost.

In a discussion a number of years ago the Swedish national sound 
archive presented the thought that analog and digital preservation 
copies should be made in parallel, and that subsequent to every 
digital change of generation a further analog copy was made. This 
would mean that there would always be an analog copy (equivalent 
to a first generation copy, which compared to digital must be 
considered reasonably un-coded) that may survive a period of 
nursing negligence. This is expensive, sort of "belts and braces", 
but theoretically very sound.

I think that there are two major concerns in preserving what we 
have today: the ensuring that the transfers from the present digital 
system to future digital systems occurs in a timely fashion, and - if 
what we have is in an analog form today - that the transfer to digital 
is done with as much consciousness about the total information 
content as possible (or that we make a conscious exclusion of 
some of the secondary information).

Oh, the burden on archivists' shoulders!


Kind regards,


George Brock-Nannestad
Preservation Tactics