[ale] Cd-r life
atllinuxenthinfo at c3energy.com
Sat Oct 2 21:00:53 EDT 2010
This message caught my eye. A few years ago, I got very interested in the
topic of data security, and, with the best of intentions, bought a domain
name with the idea of starting a business relating to protecting people's
data in various ways. Alas, I didn't have enough knowledge, tools, or
money, to really get it done. I did find some interesting information on
this very topic. With off the shelf CD's and DVD's, you're really taking
your chances. These may fail in months to a few years. I don't use
optical discs for backup. One big problem is the limited capacity. I use
redundant USB hard drives onsite for my backups, along with online
backup. Backup files are periodically added to the HDD's and
verified. Also, once in a while, I run Spinrite ( http://www.grc.com/ ) on
the HDD's and give every sector a good vigorous read / write integrity test.
There are archival grade CD and DVD discs which are projected to last 100 -
300 years based on accelerated environmental testing. Here are some links
which you might find interesting. Also, below the message is the text from
the relevant web page that I had up for a while.
These links are from a premium commercial grade manufacturer of CD's and DVD's.
TDK had a similar product at one time, but I couldn't find it on their
website now. Here's the link to their storage media website. Look for the
word archival in the name, but be sure to check the specs. Some discs are
just a heavy duty scratch resistant standard discs.
I also joined a couple of "Archivists" message groups. You can get lost
for weeks at a time reading these, but it's very interesting
info. Archivist really have a difficult job to do.
Association for Recorded Sound - http://sun8.loc.gov/listarch/arsclist.html
Records Management - http://lists.ufl.edu/cgi-bin/wa?A0=recmgmt-l
Hope this is useful.
Text from my original website page on the topic. Disclaimer, I was trying
to market this product, but the info is valid. This was from a few years ago.
I am no longer selling the product, check the manufacturer website for
GOLD Archival DVD's and CD's
The Ways Recordable DVD's and CD's Can Fail
I thought CD's and DVD's were nearly indestructible until I started
researching the issue. After I started checking into it, I found a number
of pieces of evidence that the data on recordable discs can indeed self
destruct over a short period of time.
A commercial DVD of a movie is PRESSED from a glass master disc. Thus, the
reflective surface of the disc actually has little pits in it which the
laser beam reads. This type of disc can last a very long time under proper
A recordable disc does not have any real pits. The reflective surface of
the disc is coated with a dye which either evaporates and changes color or
creates a bubble when the laser beam writes to it. This type of disc may
not last nearly as long for the reasons below.
I have talked to a rep at the factory that makes archival grade discs. He
explained several ways that a recordable DVD (or CD) disc can fail.
A recordable DVD is made by sandwiching a dye coated reflective layer
between two plastic layers, along with various coatings and glues.
Failure mode # 1: OXIDATION - I found out that the plastic part of the
disc is not waterproof, despite what we might think. Water vapor can seep
through the plastic over time. Once that happens, it can cause oxidation
of the reflective surface. If the reflective surface is made of a material
that can oxidize, it can become unreadable. Aluminum can corrode. Silver
can tarnish. The best way to prevent oxidation is to use a material that
cannot oxidize. The best material for that is PURE GOLD. So, an archival
grade disc should have pure gold at its core. Not just a gold color, real
gold. Our discs have a core of pure gold.
Failure mode # 2: DYE FAILURE - The chemical dyes used in recordable DVD's
intrinsically go through chemical reactions over time that change their
color and reaction to the laser beam. Certain dyes have been proven to
have a shorter life span and others a longer life span. The worst ones can
change in just a few years to the point that the disc is unreadable. How
do you know which is which? The only way is to look at documented
accelerated aging tests on the media. If you want a buzzword to look for,
go for Phthalocyanine (tha-lo-sy-a-neen). According to my research, this
is the best available. However, I believe this applies only to CD's. Make
sure the vendor is really using this dye, and not just putting it on the
marketing materials. An archival grade disc should use premium long life
dye. Our discs have premium long life dye. In the case of CD's, our discs
use Phthalocyanine, and the manufacturer we use owns the world wide patent
on this chemical.
Failure mode # 3: BONDING FAILURE - As mentioned above, the DVD is
produced by bonding two plastic discs together with the reflective surface,
the dye, coatings, etc. Some manufacturers don't use as high quality
bonding agents as others. Also, the 'glue' doesn't always extend fully to
the edge of the plastic discs. So, if the disc has bonding problems, and
you drop it on its edge, it might delaminate. This could cause it to
become unreadable. An archival grade disc should use premium bonding
agents and edge to edge coverage. Our discs use premium bonding agents and
edge to edge coverage.
Failure mode # 4: SCRATCHES - If you've used recordable DVD media very
much, you probably know they're extremely susceptible to scratches. Put
enough scratches on the disc, and it will become unreadable. And, it
doesn't take too many to make that happen. The way to prevent this is by
careful handling and with a scratch resistant coating. An archival grade
disc should have a scratch resistant coating. Our discs have a scratch
Failure mode # 5: PRODUCTION QUALITY - I was told that many name brand
disc sellers bid the production out to the lowest bidder. There aren't
many DVD and CD factories in the world. But, an archive grade disc is not
likely to come from the lowest bidder. Also, some of these brands change
factories from time to time as they get new bids. Therefore, the quality
may vary from batch to batch. An archive grade disc should come from the
same factory all the time which should maintain world class quality
control. Note, I didn't say the owner of the brand had to manufacture the
discs. But it is essential that they get their discs from a world class
factory. Our discs come from the same factory all the time which maintains
world class quality control.
You WANT the GOLD. You NEED the GOLD. Get it NOW!
You know you want it! Your data needs to be secure. And, you don't want
to worry about it. Click over to the BUY! page and get your own GOLD. You
can worry less knowing that you've entrusted your data to the best
recordable DVD and CD media in the world!
Our World Class Manufacturer
My world class manufacturer is none other than Mitsui Advanced Media -
America (MAM-A). Take a look at the various links on their website
http://www.mam-a.com/ . Browse around their website. I think you'll be
impressed. These are the only kind of DVD's I'm entrusting my videos to in
the future. I would say the same for data.
At 10/2/2010 09:19 AM -0400, Geoffrey wrote:
>I was under the impression that CD-Rs last a decade or more. Spotted a
>post on /. saying that recordings as late as 2008 are at risk. Anyone have
>links to real scientific data on this issue?
>Sent from my iPhone
(PS - If you email me and don't get a quick response, you might want to
call on the phone. I get about 300 emails per day from alternate energy
mailing lists and such. I don't always see new messages very quickly.)
770-205-9422 (O) Leave a message.
linuxdude AT c3energy.com
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