Answers to your questions about CD/DVD archival capacity and testing

By Tom Peterson, Product Line Manager for Rimage Corporation

Professional photographers need clear answers to their questions about using CDs and DVDs as archival media.  What causes data loss in CDs and DVDs? How do you avoid that? What is an archival CD/DVD? How do I find archival quality CDs/DVDs? How long should my data last on archival quality CDs/DVDs? What is Blu-ray technology? Do I need it?

Tom Peterson is the Product Line Manager for Rimage Corporation, providers of CD-R and DVD-R publishing, duplication and printing solutions. He is responsible for the purchase of more than two million CD-Rs and DVD-Rs each month for the company and meets monthly with representatives of all major media manufacturers to keep abreast of changes in technology. Peterson led the initiative within Rimage of working with vendors to establish the Rimage 100-year media warranty.

We asked Peterson to provide the answers you wanted.

What conditions can contribute to data loss in CDs and DVDs? (aside from breakage and splitting)

The first step in ensuring a long life for a CD or DVD is to obtain a good recording. Many people assume that since the recording is “digital,” it is either perfect, or bad, and that there are no degrees of quality.

When you record data on a CD, the drive places your data in non-adjacent locations. For example, this sentence might be spread over several different spots on a CD. Then the drive uses algorithms to error check and auto-correct if a piece of data is wrong. With these techniques, the drive can reconstruct your data, even if some pieces are missing.

A good quality recording results in very little error correction by the drive. A poor quality recording means that from day one, the drive has to do a lot of error correcting to play or read your disc. If the disc is marginal to begin with, and ages or degrades at all, you can have an unreadable disc in six months.

Here are a few tips for how to properly store and handle a CD or DVD for maximum life:

  • Avoid temperature and humidity extremes and large variations.
  • Store away from light sources.
  • Store in a jewel case, which will hold the disc vertically (Did you know that the little clip in the middle of the jewel case actually holds the disc away from both sides of the case so the recording surface only contacts air?)
  • Avoid flexing, bending or scratching, and bringing the disc in contact with dirt, dust and chemicals.
  • Never write on the top of a disc with a pencil or ballpoint pen.

What sort of testing is done to disk media to gauge archival longevity? Is this testing actually a reliable determiner, or just a best guess of how to reproduce the effects of time and other contributing factors to data loss?

There is an organization in Switzerland, the International Standards Organization (ISO), which is responsible for developing and publishing standards and tests. They have a special test for determining the life of data on optical media. This test, ISO 1827-2002, is used by media manufacturers to determine data life. The test itself takes approximately 18 months to run and uses cycles of heat and humidity to accelerate aging on recorded discs. This same type of testing has been done for many years to determine the life of photographic prints, for example.

How long can a user expect a standard consumer-grade CD or DVD to reliably hold data (assuming proper care and storage)? How long can a user expect an archival-grade CD or DVD to reliably hold data (assuming proper care and storage)?

Assuming a good initial recording and proper care, consumer grade media can last from one to five years. Professional or industrial-grade media can last from five to 75 years. True archival-grade media, often with a reflective layer of gold, can last 75 to 200 years.

How can a user determine whether the CD/DVD they're buying is archival grade? What information should they look for?

Archival grade media is only made by a few companies, often has a gold reflective layer and is usually identified as such. The Internet is a good source to purchase this media, since the average office store does not carry it.

Well-known brand names are usually not an indication that a disc is archival grade. Many of these companies buy media from several sources and often buy budget media when a manufacturer has an oversupply, and then put their brand name on it. For example, you will often see the HP name on media, but HP does not own or operate any media manufacturing facilities.

If you spend time on Web sites devoted to CD quality, you will start to see some brands consistently appearing at the top of everyone's ratings or quality tests. These companies are Taiyo Yuden, Maxell, Ricoh, TDK, and Verbatim. Taiyo Yuden is what most people who use media for a living will buy. It is very high in quality, very consistent, and has performed very well in the ISO 1827-2002 test.

A branch of the federal government, NIST, is working on universal standards that all media manufacturers will adhere to that will label media with an estimated life. We are at least a year away from that goal.

What is blu-ray technology and what benefits does it bring? What problems might its adoption bring?

A CD can hold up to 700 MB of data. A DVD uses a smaller spot laser and can hold up to 4700 MB or 4.7 GB of data. A blue laser disc uses an even smaller spot laser and should hold up to 25 GB of data on one disc. When each new format comes out it usually is expensive, sometimes making adoption slow. Today, a quality DVD may cost $.75. A blue laser disc will hold five times as much as a DVD, but will probably cost 30 times as much initially. Only people who really need to get all their files on one disc will be able to justify the price premium.

About the Author

Tom Peterson is Product Line Manager for Rimage Corporation, the world’s leading disc publishing company. He is responsible for Rimage's Media Kit program, which includes packaging all media with Rimage printer consumables. Peterson coordinates the purchasing of more than two million CD-Rs and DVD-Rs each month for Rimage. He meets monthly with representatives of all major media manufacturers to keep abreast of changes in technology. Peterson led the initiative within Rimage of working with vendors to establish the Rimage 100-year media warranty.

Do you have other questions about archival media? Ask in the Comments section below.

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Comments (16)

Richard Dawson:

Trying to maintain the quality of data is an important issue in many situations. A lot of systems designed by software engineers accept that communication systems and storage systems are inherently unreliable, which is why CD/DVD have extra recovery data written to them.
It is also possible to use a technique called Reed-Solomon error correction yourself. This works by creating redundant information or revovery information for a file/set of files or a CD/DVD anything you like in fact.
This link explains more about this technique http://en.wikipedia.org/wiki/Reed-Solomon_error_correction and this is a link which descibes a tool which can be used to create the error correction data http://en.wikipedia.org/wiki/QuickPar I use this technique a lot

C. M. Heldt:

Great article, good reading! - Thank you.

I have two questions, the first is regarding the labeling of CDs and DVDs.

Is it safe/advisable to stick labels directly onto a CD or DVD? I read somewhere that this is NOT a good thing to do and would lead to disc damage.

My second question is, although disc life can be anything upto 200 years, what happens as technology changes and other methods of information storage are introduced. DVD and CD readers/writers may become obsolete. How often would you advise backing up and re-recording information, inorder to keep abreast of technology changes and progress?

I have been using MAM-A, (www.MAM-A.com) formerly Mitsui, gold CDs for several years now as my archival media. I am now using their silver DVDs ( the gold DVDs are a bit pricey). While you did mention gold, you did not mention this brand. Most of my colleagues use them too. Any comment.

What about media with a printable face? Is it safe to use media with a printable face?

Geoff Hughes:

You mentioned jewel cases safeguarding the recording surface by suspending it in air. What about CD envelopes? Are they inherently damaging to the recording surface?

Jamie Karutz:

In what format should a photographer save/archive images- raw, tiff, jpeg or another format? When saving files as jpegs, how important is the change from 16-bit to 8-bit color?

Thanks for the comments, here are some answers.

1. Thanks Richard, for the link to more info on Reed-Solomon. I will use that myself!

2. CM Heldt, that is a tough question. I think most people now with music or data on cassette tapes or video on VHS tapes are seeing the writing on the wall and copying them over to CDs and DVDs. I assume that someday we will be in the same position and will have ample warning to re-record to whatever comes next.

As for stick-on labels, the most common danger I am aware of is that they will come off on a hot day in the CD player in your car and you will be very sorry. For home use, or even cars, use a Sharpie.

3. Bob, both MAM-A and TDK make gold media. I am partial to MAM-A gold for various reasons and if I had data that had to last 200 years or in extreme conditions, that is what I would use. MAM-A's silver CDs may be manufactured in Italy, France, or the US. I find them to be of high quality but did not mention them because with all the names, MAM-A, MAM-E, Mitsui, etc. some people get confused.

4. Alexandra, most commercial or industrial media has a printable surface, either inkjet or thermal. This is applied by silkscreening white (or another color) onto the surface of the finished disc. I have not seen any evidence that this can damage a disc and in fact some people feel it offers an additional layer of protection.

5. Geoff, I have not seen any evidence that an envelope or Tyvek sleeve can damage a disc over time. But, every article and paper I have read recommends jewel cases.

6. Jamie, file formats are outside my area of expertise. But, I think raw files are somewhat manufacturer dependent, which would concern me. When we get high-res product shots, we always ask for tiff images, which I would assume is one of the best formats.

To answer Geoff:

I would recommend you always save in the RAW format and either a PSD (Photoshop File Format) that has all your work layers or as a TIF file.

Treat RAW as you would a film negative, it is your source file, so always keep them. TIF is a losless format so it is always preferred for most uses.


This is how I am doing my setup, it may or may not help you or someone else:

1. Copy RAW files to computer and create a backup cd/dvd at that moment.

2. Create second cd/dvd that goes into storage away from your location for a redundant backup.

3. Mirror all RAW and working files on an external drive. To be anal about it I keep my drive turned off when I am not using it and when it is full it is replaced with a new drive and then put into safe storage with the CD/DVD backups offsite.

This may all seem a bit much, but when you loose some of your most important source files because of flood/fire/data corruption you will see why I am doing it this way now.

William Rippey:

Hi!
Two related questions: Can placing a DVD in a CD drive and attempting to read it cause damage to the CD drive or the DVD, and can/will the drive so treated damage CDs or improperly record data?

Thanks!

Walter:

You did not mention Kodak in your list of brands for archival storage. Yet Kodak has an extensive writeup of their Ultimate Media. Any comment?

Lorin Lund:

How can I find out if a disk I have just burned is a good quality image? I.e. reads back without need of error correction? If it is bad what can I do to get a better write if I do another disk?

Marlo:

I just bought a stack of Fujifilm DVDs which come with a lifetime guarantee. Does this also mean they are archival quality? Are these also a recommended brand?

David:

Like Lorin, I would like to know how we can figure out that error detection is being employed during the reads. If the correction is occurring in the drive, then the O/S may not even be notified.

Second, are some CD and DVD drives rated differently relative to archival quality?

I write a "Burn Date" on all of my optical media to alert me to make copies before two years have elapsed.

I have been maintaining my personal data on duplicated removable hard drives due to concerns about optical media. I would certainly like to find a reliable optical media solution.

christine:

Hello, what does it mean when, after inserting a disc, I get a message that says this disc is "read only" and is there a way that I can access the data?? which in this case is an important video file??

Christine, Generally, that means that you cannot write additional data to that disc. You should be able to view the data on the disc. If the data (video file) was written to the disc with security settings that prohibit copying, you will not be able to copy it to another location. If that's the case, you would get a message that says something like "Could not copy because you do not have permission." The disc may also be formatted in a way that launches the video to play but does not give you access to the files. This is also a method security protection for the creator of the file to prevent others from copying content without permission. That's my best answer without having the disc to look at.

Pat Meyer:

I have recently had an old reel to reel audio tape transferred to a CD. I now want to copy this recording to archival quality cd to share with family. First of all I know to purchase top quality archival discs. But, can I copy the cd with the software on my own computer? I am not looking for a professional quality cd but want to archive family history recorded 55 years ago by multiple family members.

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