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08-24-2010, 11:28 PM
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I ran a quick Google search tonight, looking for that baloney article from about five years ago (the one where it was claimed that DVDs only have a life expectancy of 2-5 years), when I came across this shocking discovery: http://www.archives.gov/records-mgmt...media-faq.html

The page is full of myths and horsepuckey.

For example:
Digital Versatile Disc or Digital Video Disc (DVD) is a type of optical disk technology similar to the CD-ROM. A DVD holds a minimum of 4.7GB of data with enough memory for a full-length movie. DVDs are commonly used as a medium for digital representation of movies and other multimedia presentations that combine sound with graphics. Source: www.webopedia.com.

For starters, they're using webopedia.com -- a low rent site that's basically what existed before wikipedia came out. (Wikipedia, while decent for what it is, is absolutely NOT an accredited or authoritative text of any kind, as any idiot can write whatever he/she wants -- and it may stay that way if nobody catches it, or if enough biased "editors" [unqualified volunteers, usually] decide to agree with it!)

A minimum of 4.7GB?

That's ridiculous. I can store 1 kilobyte and let it create a 1GB lead-out, if I felt like it. But I'll go ahead and chalk that up to human typing error -- let's assume it should have stated "maximum".

But then it goes on to list a size of "4.7GB" which is wholly inaccurate. A disc only holds 4.38GB, when using actual computer-based 1024 block math. The only people who use "4.7GB" are the marketers writing the disc packages. A professional source would know this, and would most likely mention it. It's safe to assume this "article" has been loosely cobbled together from other sources, and the editor (which appears to be absent, as you'll see in a moment) doesn't really understand optical media whatsoever.

Let's continue...

5. What is the shelf life of unrecorded CD-R/DVD-R discs?

It is best to purchase new CDs/DVDs as they are needed. According to the Optical Storage Technology Association (OSTA), the unrecorded shelf life of a CD-R/DVD-R disc is conservatively estimated to be between 5 and 10 years. Source: http://www.osta.org/technology/cdqa13.htm

6. How long can I expect my recorded CDs/DVDs to last?

CD/DVD experiential life expectancy is 2 to 5 years even though published life expectancies are often cited as 10 years, 25 years, or longer. However, a variety of factors discussed in the sources cited in FAQ 15, below, may result in a much shorter life span for CDs/DVDs. Life expectancies are statistically based; any specific medium may experience a critical failure before its life expectancy is reached. Additionally, the quality of your storage environment may increase or decrease the life expectancy of the media. We recommend testing your media at least every two years to assure your records are still readable.
So within one inch, on the same page, it goes from 5-10 years to 2-5 years? Dear editor, where are you?

Then it defers to a bunch of random studies from figure 15 which, while good for what they are, lack context for the layman. (Even better, none of the links work, because the "external link" page code seems to be broken.)

Beyond that, having manually located the linked documents, I don't see anything that would have resulted in the "2 to 5 years" lifespan. This sounds like a rip from that poorly-written article in 2005 that suggested optical media was some sort of death trap for data. Since it relied wholly on one IBM magnetic media engineer as the source of information, it comes as no surprise that magnetic tapes/disks were suggested as the only viable media for archival storage. Yeah, that wasn't biased or anything. (Rolls eyes.)

Sigh. Let's continue...

12. What is the preferred method for labeling CDs/DVDs?
CDs and DVDs or their containers are labeled in some form or fashion so that they can be identified and organized according to your inventory. Many vendors sell CD-safe markers. For risk-free labeling of any disc, it is best to mark the clear inner hub or the so-called mirror band of the disc where they contain no data. Do not apply adhesive labels to the CD/DVD because they can damage the disc.
Let's analyze this piece by piece.

Many vendors sell CD-safe markers.
... and these are items that are wholly unnecessary. It's nothing more than a profit grab by the companies that make these. Research shows that pretty much any normal marker, such as a Sharpie, is no more or less harmful to optical media surface than the so-called "safe" kind. Anybody up to speed on optical media would know this.

inner hub or the so-called mirror band
The hub is not the same thing as the mirror band. Beyond that, it would be very difficult to write in this small area (the band). The hub, sure, you can squeeze in a word or two, maybe a unique ID code for your inventory system. Even hub labels are pretty safe.

At least the adhesive labels comment was accurate.

Let's continue to (by far) the most boneheaded advice found on this page...

4. What is the significance of different colors for CDs/DVDs?
The color of a CD/DVD indicates its quality. It is best to look for a gold or silver CD/DVD - look at the color from the underside of the disk, not the top. In addition, to assure the highest quality of a CD-R, look for those manufactured using phthalocyanine dye with gold or silver reflective layers. Do not use Azo- or (plain) cyanine-dyed media. For DVD-Rs, purchase double-sided/single-layer with a gold reflective underside. To assure you're using the highest quality CD/DVD and/or to avoid pitfalls in purchasing the correct type, refer to the source references in FAQ 15, below.
This is the kind of quality information I'd expect from a Best Buy salesman, not the National Archives.

Let me make this absolutely clear: Color has absolutely zero relation to the quality of media.

Beyond that, it seems to buy into the ridiculous marketing of Mitsui (now MAM-A) that gold and phthalocyanine somehow the best materials for optimal media. On both counts, that's ridiculous.

For starters, a lot of discs using phthalocyanine burn poorly -- so that's that. Taiyo Yuden, regarded as the industry leader in CD-R, followed closely by Mitsubishi (Verbatim), doesn't use either material.

Gold media routinely proves itself to be less reflective than silver-based media. This is one reason companies like Taiyo Yuden and Mitsubishi -- who pride themselves on quality, and not merely costs -- don't use it.

Verbatim seems to have created a "gold archival" line of discs simply because some people are dumb enough to insist on buying it. But you know what? The reflective surface of the disc, the underside of the media, uses a silver alloy, while only the top uses the gold to "make it pretty". Now ask yourself why a company would choose to use the harder option (combining to separate foils) as opposed to using a single sheet of metal?

Azo is also one of the most readable dyes there is, and it's a stabilized metallic dye used by Mitsubishi Kagaku Media (MKM) a.k.a Mitsubishi Chemicals Corp (MCC). In terms of longevity, it will remain and easy-to-read surface through the years, even as it ages -- possibly more than so-called "longer lasting" dyes.

Double-side media only comes in one flavor: Ritek. That's a pretty dismal disc by most experiences, and the double-sided variation hasn't been manufactured for years now, due to higher manufacturing defect rates (or so I've read, and from reliable sources). It's also far easier to mishandle a double-sided disc, since neither side is what you'd consider "safe" for general handling -- i.e., not touching the "data surface" of a media.

I would also note that pure silver is almost never used as a reflective surface because it tends to react poorly with other materials in the disc, such as the dye. For that reason, most "silver color" metals are alloys that have been stabilized specifically for optical disc use.

Although I've already discounted wikipedia as being a reliable source of information, I want to quote something that is as well-written as it is accurate, regarding the nature of CD-R dyes:
However, phthalocyanine is more sensitive than cyanine to writing laser power calibration, meaning that the power level used by the writing laser has to be more accurately adjusted for the disc in order to get a good recording; this may erode the benefits of dye stability, as marginally written discs (with higher correctable error rates) will lose data (i.e. have uncorrectable errors) after less dye degradation than well written discs (with lower correctable error rates).
Azo is the most resistant dye against UV rays and begins to degrade only after the third or fourth week of direct sunlight exposure.
many manufacturers have added additional coloring to disguise their unstable cyanine CD-Rs in the past, so the formulation of a disc cannot be determined based purely on its color
How is it that a random wiki user knows more than the National Archives?

Final analysis...

I don't know what moron wrote this page at the National Archives, but it's probably some of the most ill-conceived myth filled crap advice I've ever seen on a site that claims to be a guardian of media archiving. Having read this this page, I'm shocked that they are somehow entrusted with documents like the Magna Carta and Declaration of Independence. Good thing those pieces are not on discs!

Their knowledge on paper archiving clearly doesn't translate to the digital realm.

I just don't know how exactly to express my disappointment with the National Archives.

This is just so sad.

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Last edited by kpmedia; 08-25-2010 at 12:32 AM.
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