| Below are two articles based upon a report by Kurt Gerecke
DVD and CD Life Expectancy: News Story by John Blau (Computerworld) January 10, 2006 Although opinions vary on how to preserve data on digital storage media, such as optical CDs and DVDs, Kurt Gerecke, a physicist and storage expert at IBM Deutschland GmbH, takes this view: If you want to avoid having to burn new CDs every few years, use magnetic tapes to store all your pictures, videos and songs for a lifetime. "Unlike pressed original CDs, burned CDs have a relatively short life span of between two to five years, depending on the quality of the CD," Gerecke said in an interview this week. "There are a few things you can do to extend the life of a burned CD, like keeping the disc in a cool, dark space, but not a whole lot more." The problem is material degradation. Optical discs commonly used for burning, such as CD-R and CD-RW, have a recording surface consisting of a layer of dye that can be modified by heat to store data. The degradation process can result in the data "shifting" on the surface and thus becoming unreadable to the laser beam. "Many of the cheap burnable CDs available at discount stores have a life span of around two years," Gerecke said. "Some of the better-quality discs offer a longer life span, of a maximum of five years." Distinguishing high-quality burnable CDs from low-quality discs is difficult, he said, because few vendors use life span as a selling point. Hard-drive disks also have their limitations, according to Gerecke. The problem with hard drives, he said, is not so much the disk itself as it is the disk bearing, which has a positioning function similar to a ball bearing. "If the hard drive uses an inexpensive disk bearing, that bearing will wear out faster than a more expensive one," he said. His recommendation: a hard-drive disk with 7,200 revolutions per minute. To overcome the preservation limitations of burnable CDs, Gerecke suggests using magnetic tapes, which, he claims, can have a life span of 30 to 100 years, depending on their quality. "Even if magnetic tapes are also subject to degradation, they're still the superior storage media," he said. But he's quick to point out that no storage medium lasts forever and, consequently, consumers and business alike need to have a plan for migrating to new storage technologies. "Companies, in particular, need to be constantly looking at new storage technologies and have an archiving strategy that allows them to automatically migrate to new technologies," he said. "Otherwise, they're going to wind up in a dead end. And for those sitting on terabytes of crucial data, that could be a colossal problem." CDs, Lies, and Magnetic Tapes: News story by Larry Medina (Computerworld) Jan 10 2006 As I've heard said many times, "... the more things change, the more they stay the same ..." This article regarding the sensitive nature of media and options for long term storage of information goes a long way towards pointing out the obvious, and something RIM Professionals have been trying to convince people of for years now. "Unlike pressed original CDs, burned CDs have a relatively short life span of between two to five years, depending on the quality of the CD," Gerecke said in an interview this week. "There are a few things you can do to extend the life of a burned CD, like keeping the disc in a cool, dark space, but not a whole lot more." The problem is material degradation. Optical discs commonly used for burning, such as CD-R and CD-RW, have a recording surface consisting of a layer of dye that can be modified by heat to store data. The degradation process can result in the data "shifting" on the surface and thus becoming unreadable to the laser beam. There's nothing that beats the establishing of a sensible media migration policy, one that takes into account not only the usage pattern and methods for storage of media, but considers the value of information being stored on the media. And there are a FEW more things you can do to extend the length of time you can access information stored on CDs, such as burning a second copy that is stored in optimal environmental conditions, not using pens to write on the surface of the media, not applying adhesive labels to them, and keeping them in their jewel cases. However, the problems don't stop with the media itself. Consideration needs to be given to the formats the information is stored in, and ensuring you are able to have persistent access to the format, at minimum, equivalent to the time it's required to be retained. There is also the issue of hardware obsolescence to consider. It's imperative to ensure the hardware used to access the information on the media remains viable for the assigned retention period as well. The article goes on to recommend the use of magnetic tape as a better case alternative. "To overcome the preservation limitations of burnable CDs, Gerecke suggests using magnetic tapes, which, he claims, can have a life span of 30 to 100 years, depending on their quality. "Even if magnetic tapes are also subject to degradation, they're still the superior storage media," he said." ... but there are other considerations related to magnetic tape also. Tape is very sensitive to heat, magnetic fields and dust. It also needs to be stored vertically, and periodically re-tensioned. Care needs to be take to ensure the wall adjacent to the area where tapes are being stored isn't an elevator bay or a switcher room, both of which contain large magnets and magnetic fields. And consideration should be given to housing the tapes in six-sided cabinets, properly rated for the protection of media and that they are protected with gaseous based fire protection. He also correctly points out the need to be ever diligent in the protection of information and not relying on things to remain as they are forever: "But he's quick to point out that no storage medium lasts forever and, consequently, consumers and business alike need to have a plan for migrating to new storage technologies. "Companies, in particular, need to be constantly looking at new storage technologies and have an archiving strategy that allows them to automatically migrate to new technologies," he said. "Otherwise, they're going to wind up in a dead end. And for those sitting on terabytes of crucial data, that could be a colossal problem." But the fact that the recommendation being made is to go backwards to an older, less technological alternative, such as magnetic tape over CDs and even hard drives indicates we shouldn't be too quick to jump to untested technologies!  Also check out this Associated Press article that appeared in newspapers across the country: 
A final word from Larry Medina in response to negative Blogs: I encourage readers to look at the NIST report on the Care and Handling of CDs and DVDs, Publication 500-252 NIST DDDP. To date, this is the single most valuable publication that speaks to the need to exercise special care to ensure the longevity of not only the MEDIA, but more importantly THE INFORMATION contained on it available for use. The report points out (pg. 15) that manufacturers of CD-R, DVD-R and DVD+R discs state a shelf life of 5-10 years before recording, but don't speak to life after recording. It's also important to note the liability of the manufacturer is limited to the discs being handled in accordance with their specifications and if they ARE found to be at fault for the media failing, their limit of liability is to replace it with similar blank media. And yes, RW discs have a much shorter lifespan. Again, the concerns here go beyond the possible lifespan of the media itself to issues relative to the format in which the information is recorded and your ability to access it, and the availability of hardware to read the media. Ultimately, its imperative to establish a system to encourage periodic conversion and migration of information irrespective of the media its stored on to ensure persistent access. Some of you may find in this report that your thoughts related to dyes, substrates, construction materials and other aspects of the physical construction and capture of information on CDs (R or RW) may not have been completely accurate. While this report was written in 2003, I doubt much has changed to invalidate the information presented. Larry Medina Danville, CA Records and Information Management Professional |