SOPORTE - Digital Archiving & Storage FAQs - General

Is CD/DVD media quality sufficient to replace paper for Long-term Archiving?

As you can expect, we would belong in the camp that supports the archival of data on optical media like CD and DVD. Indeed taking paper offsite will limit the risks of damage to it, but still paper stays susceptable to fire, insects and bad environmental conditions. Storage of paper in conditions that eliminate these risks is not only expensive, but also very unaccessible.

Keeping paper off-site means that you are dependant on others to retrieve information, and you are limited to searches for labels put on the outside of the storage compartment. A time lag is unavoidable in this case (also if you go in yourself) and there is a reasonable risk that information can not be found, either by errors in the labelling, or inaccurancy in the search criteria.

Storing information digitally with todays technology, will allow for easy access, searching by content from behind a PC and fast retrieval of files for anybody that requires it. For instance your signed documents would be scanned and subsequently OCR (Optical Character Recognistion) would be applied to index all content of the document. Also the ability to input several categories, descriptions, key words is possible. A simple web browser will allow you search for any combination of "meta data" all indexed data of a document and you can literally have a document on your screen or in the printer within one or two mintes from the time you wonderred where it could be.

As far as digital storage media goes, CD and DVD (we do make a strong distinction between brand labels media like Panasonic, Mitsui and Verbatim versus cheap media from the local retail chain, those have proven to be of lot quality and reliability) are still the most depandable digital media out there. Of course it is still possible to damage these media, and care should be taken when storing them, however the same goes for paper. And that will sure need a lot more storage space!

And availability of technology to read CDs or DVDs in the future is also almost guaranteed. I will explain: The comparison with tape and floppy is not realistic. Both CD and DVDs are not only used in the computer and storage industries, they are also consumer standards! If you count the number of Music CDs in your house and possibly also Video DVDs in your house, and think of how many there could be in US alone, you will see that even 10 or 20 years from now there will be a commercial gain to made to produce equipment to read these media. Compatibility paths from CD to DVD were promised and deliverred, PC and consumer applications are also interchangeable, these compatibility paths for the 120mm optical technology will be maintained in the future simply because the consumer demands it.

With automated solutions like the SmartDAX, it is certainly possible to burn duplicates even automatically and export one to another location. It is even possible to have one created at another location so no intervention is required at all (and human errors are eliminated). In a system like the smartDAX, media are kept in relatively controlled environment closed of from light and dirt. All media can be automatically accessed by anybody on the network (with permission), so nobody has to get up from his chair.

Archiving on CD/DVD: can I safely buy any media brand?

This is best explained by the following anecdote, by Jeremy Wagstaff:

"I threw out hundreds of floppy disks the other day, some of them dating back to the Vietnam War. It was an emotional moment, ditching those little plastic fellas, but they were taking up valuable space, and their contents have long been transferred to CD-ROMs (each of which holds about 500 floppies worth of data). But then I came across an article in a Dutch PC magazine called PC Active that froze me in my tracks. It said (well, an automated translation of it said, because my grasp of Dutch is limited) many CD brands cant be relied on to store data for more than a year or so, even when you store them properly (out of sunlight, at room temperature, with back issues of The Countryman magazine for them to flip through). Yikes. Could this be true?

Well, after exhaustive research, I can safely say: sort of. The answer is a tad complicated and involves understanding what we do when we burn a CD, but bear with me because its kind of interesting. (I know, I know, this is where half of you skip to the last paragraph.)

First, what exactly is a CD? Its basically a piece of see-through plastic with very thin layers of other stuff on top. The plastic is there for protection. Its what is in the layers that is important. (A pre-recorded CD -- whether its a music CD or a software CD-ROM -- is a bit different from one you burn at home. We are talking here about a blank CD -- what is called a CD-R, or CD Recordable.)

Beneath the plastic is a thin layer of dye, which is designed to react to certain frequencies of light. In other words, the dye is basically being cooked by the CD writers laser -- hence the term "burning." Remember, all this is going on to store digital data -- binary ones and zeros -- so all the laser has to do is change the dyes appearance to create a one, or not change it to produce a zero.

Below the layer of dye is another thin layer, of either gold or aluminum. When the laser reads a finished CD-R, instead of cooking the dye, the laser beam will bounce off the aluminum or gold layer. If there has been no change in the dye, the laser beam will bounce back up directly at itself, generating a burst of electrons in the laser head that are converted to binary digits. If there has been a change in the dye, the
laser beam will get confused and scatter in different directions. The not-bouncing-back-to-the-beam-head thing provides the other part of the binary puzzle.

So, why do we need to know all this, I hear you ask? Well, the difference in CD quality that our Dutch friends spotted largely comes down to the quality of the dye and the metal layers. First off, the dyes: Im going to have to use a couple of long words here, but I promise not to overdo it. There are three main types: phthalocyanine, which is transparent; cyanine, which is blue; and metalized azo, also blue. That is why, depending on whether the metallic layer is aluminium or gold, the CD-Rs you see in shops are sometimes green, blue or gold. OK, that is the last time I am going to write phthalocyanine, but am I the only person who thinks that is a great name for a drink?

Given these different components, and the complexity of the CD-writing process, you can see why the quality of CDs might vary. Phthalocyanine CDs (sorry, I wrote it again -- that is really the last time, I hope) are supposed to last up to 100 years, but of course, no one knows for sure that they do. Cyanine CDs are supposed to have a higher writing speed -- meaning you can burn them more quickly -- but last only between 10 and 20 years.

All this said, here is my advice to avoid having a cupboard full of CDs you can no longer access.

Do not buy cheap CD blanks unless they are for disposable stuff: MP3s for a car trip, transporting files from the office.

Back up your valuable data regularly to good-quality CDs and make two copies (duplicates!).

When you burn a CD, follow the recommendations on the box. Different CDs work best at different speeds: Burning slowly isn't necessarily better. If your software has a "verify" function to check that the data on the CD you have burned is OK, use it.

Avoid sticking labels or writing on your CDs. Doing so can affect their spinning speed, and hence their lasers. Also, over time, the chemicals in the pen, the glue or the label can seep through the CDs outer protective lacquer and damage the aluminium and dye.

Store the CDs in a jewellery box in a cupboard away from sunlight and high temperatures. Ultraviolet light and oxygen can react with the dye and disrupt the data.

In case of natural or man-made disasters, keep your CD back-ups far away from your computer -- and I do not just mean across the room. Keep them in another building, another postal district, even at your moms place."

Having read this, it is safe to use CD/DVD technology as you long-term archiving solution. As long as you stay away of the cheapest "white-label" media brands, but select the better known brand labels, you can sefely rely on the longivity of the media. Also, the fact that CD/DVD technology is a "consumer-standard" (see also here), makes it a techology "to stay".