We have found that there are 2 key elements in the "longevity" of CD-R's.
1. Burn speed. Everything I have read recommends never going over 8x if you
want it to last. We burn all ours at 4x. (I will explain why)
2. The coating on the CD-R.
We have personally found the Memorex CD-R Blacks are the best for us.
Our test have nothing that is older than 5 years and we have seen those very
old CD-R's fail.
During our goof-off time one of our testing procedure is this. We have a
very old Music CD player 1993-ish. We tested all different CD's at
different speeds. Only those burned at 4x or less and FINALIZED consistently
played on that player. Some of the very cheap CD-R would not play at all.
Scratching or exposing the CD-R's to UV's makes all bets off.
Store them Cool and Dry, and if they are extra valuable reburn them every
2-3 years.
Here are to good write-ups on CD-R's.
http://www.melbpc.org.au/pcupdate/2106/2106article14.htm
http://www.mscience.com/survey.html
______________________________________
Dave Kleiman, CISSP, CISM, CIFI, MCSE
www.SecurityBreachResponse.com
-----Original Message-----
From: Greg Freemyer [mailto:greg.freemyer@gmail.com]
Sent: Monday, November 22, 2004 16:30
To: Jerry Shenk
Cc: forensics@securityfocus.com
Subject: Re: DVD burner for archival image copies
I would not assume that DVD backups will have a long life-time. I have not
seen any field tests of lifetime for DVDs, but for CD-Rom some of the
real-world testing showed they were only reliable for a year or so.
If you do any research on this, be sure to differenciate between
Manufactured DVDs and ones made in a typical DVD writer. That was the big
difference for CDs. Manufactured (or pressed) CDs do last a long time, it
is the burned ones that don't.
As far as I know, good tape media is still the preferred archival storage
medium, and even it is only rated for 20 years. I guess you know a good
tape drive is still pretty expensive.
Greg
On Thu, 18 Nov 2004 22:29:11 -0500, Jerry Shenk
<jshenk@decommunications.com> wrote:
Has anybody used a DVD burner to make archival copies of images on a
linux-based forensic computer?
What I imagine doing is dumping an image to a DVD(s) after an analysis
is over so that the image can be archived for an indefinite period of
time. I'd think I could use something like "dd
if=/images/TestCase_hda1.img | dvdrecord -dev=0,0,0 -data -".
Obviously that doesn't work or I wouldn't be asking the question.
Once I get that working, then I'm gonna want to be able to burn larger
images to multiple dvds using some combination of the skip and count
switches...but one thing at a time;)
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