Message-Id: <mailto:199506121743.KAA37707@listserv.ccit.arizona.edu> Date: Mon, 12 Jun 1995 13:42:30 -0400 From: Judi Zidar <mailto:jzidar@NALUSDA.GOV> Subject: Re: CD vs. Optical disks To: Multiple recipients of list IMAGELIB In-Reply-To: <mailto:199506090206.TAA64501@listserv.ccit.arizona.edu>
> Do most people use CD's or high capacity read/write optical disks for
> storage? I have just read an article from the Jan '95 issue of Scientific
> American regarding the danger of storing documents on CD's. Any
> comments on this article?
I use both CD-R and 5 1/4" magneto-optical discs in my scanning program.
During data capture and other processing work, the optical disc is
perfect. It interacts with my data capture and document management
software just like a hard disk (though slightly slower), and lets me
utilize the power of my software to move files around, build a directory
and file structure, etc. We perform various quality control checks, and
can make changes to the files on the optical drive until we're satisfied
that the data is clean. (There is a limit to the number of times you can
erase and re-write data to optical, but we have never come up against
that limit, and I'm not sure what it is.)
When the data is ready, we send it to the CD-R workstation hard disk,
index it with our authoring software, and then write it to CD-R. To write
to CD-R, we have to use special software that can create and write in the
ISO 9660 format. It does permit the creation of directories and performing
some structuring, but it would be pretty tedious to do this with the
thousands of files and hundreds of directories we need for the CD. We
also have to devote the workstation ENTIRELY to writing the CD-R disc.
Even the screen blanking that Windows can do will interrupt the session,
which could ruin the disc. So we can't use our document management
software in an interactive way when writing to CD-R, as we can when
writing to the magneto-optical drive, and this is one reason we use both.
CD-R (and CD-ROM) is my preferred archiving medium, because it's the most
standardized and the most likely to be readable on systems 10 or 20 years
in the future. In the 9 years we've been doing this, we've had to
migrate to new optical disc formats twice, and I'm now using a new
optical system that is completely incompatible with the older ones. We
have to maintain a 386 computer running under DOS 5.0 in order to read
our older optical discs, because 486's and pentiums are too fast for the
older optical drives, and the format of the discs is incompatible with
DOS 6.x. By comparison, we can still read our earliest CD-ROMs,
including those written in the High Sierra format. I plan to migrate to
CD-R discs everything on the old opticals that is not yet on CD-ROM so I
don't have to worry about this again for a while.
I did see the article in Scientific American. It was well written and
thought provoking, and I was glad to see the issues he raised being
discussed in something other than computer journals. The truth is that
CD-ROM is the best we've got right now, and that's why so many people are
using it. There are certainly no guarantees with it, though.
--Judi Zidar
% Judith A. Zidar, Coordinator % Internet: mailto:jzidar@nalusda.gov %
% Natl. Agric. Text Digitizing Program % Phone: (301) 504-6813 %
% National Agricultural Library, USDA % Fax: (301) 504-7473 %
% 10301 Baltimore Blvd. - Rm. 013 % %
% Beltsville, MD 20705-2351 % %
On Fri, 9 Jun 1995, Francis Huang wrote:
> Do most people use CD's or high capacity read/write optical disks for
> storage? I have just read an article from the Jan '95 issue of Scientific
> American regarding the danger of storing documents on CD's. Any comments on
> this article?
>