Subject: Beware about CD ROM Data Longevity - Was Re: Saving 100GB of data for 15 years cheaply

From: Jeff Bloch <jbloch at alexis>
Date: Sun, 13 Aug 1995 12:46:03 -0600

We store 650MB of satellite data on a CD ROM every 5 days using a setup from
Young Minds on a Sparcstation. We have over 100 CD volumes in the archive.
All has been well for the last two years until Sun started shipping new 4x CD
ROM readers from Toshiba with new workstations. Suddenly, 50% of our archive
is unreadable by the new drives. Old drives (mostly Sony) continue to read
the archive just fine. This has nothing to do with the ISSO standards. Young
Minds has not quite fessed up to the problem yet, but there may be a hardware
problem with the particular model of the Phillips writer that we have. 

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Jeffrey Bloch					Office:     (505) 665-2568
Astrophysics and Radiation Measurements Group	ALEXIS Soc: (505) 665-5975
Los Alamos National Laboratory			FAX:	    (505) 665-4414
Group NIS-2, Mail Stop D436			e-mail:	    jbloch at lanl.gov
Los Alamos, NM 87545
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From: Jeff Bloch <jbloch at alexis>
Date: Mon, 14 Aug 1995 09:47:07 -0600

The folks here who did the CD ROM study pointed out to me that I made an
error in my message below. Toshiba 2X readers provided in new Sparcstations
exhibited the problem, and actually a Toshiba 4X reader did not exhibit 
the difficulty. The actual failure rate was 20% to 50% depending on the 
reader. We have both a Phillips "CDD 521 Upgraded" writer and an older 
"CDD 521" model. Disks written with the older model also show no 
difficulties with any drive, just ones written on the newer writer.