The M-Disc: Enduring But Possibly Doomed

The recently released Millenniata M-Disk is an optical disk designed to last a thousand years (hence the name). Hitachi makes the drives, which use a laser 5 times more powerful than a conventional DVD burner. The discs contain the same amount of data as a conventional DVD and are designed so that a conventional DVD drive can read it, but not write it.

How they did it?

Commercially produced prerecorded CDs and DVDs rely on a series of pits (holes) and zones (not holes) molded into the disc’s clear polycarbonate bottom layer. On top of that is a thin reflective layer of metal. A laser shines through the bottom of the disk and the unit reads the difference in reflectivity between the holes as data.

DVDs and CDs are a type of optical discs, as the data is read optically using laser light.

The holes are on top of the polycarbonate layer, which is itself topped by a shiny metal layer, to reflect the laser. There is a layer of lacquer to protect the glossy layer and then (sometimes) artwork on top.

Recordable discs have a very similar construction, but instead of holes molded into the polycarbonate layer, there is a layer containing a photosensitive dye, with the thin metal reflective layer on top. The laser writes to the disc by changing the color of the dye. The unit reads the difference in tint reflectivity rather than pitting.

The new Disc M uses a laser to etch holes into the writable layer, rather than changing the color of a dye. The laser then reads the difference in media reflectivity in the data layer. Perhaps (since the disc is backward compatible with standard DVD players) there is a reflective layer on top of that, or the data layer itself is reflective. So as a readable medium, it works much like a manufactured music CD, with physical holes that provide the difference in reflectivity when a laser shines on it.

The manufacturer claims that these discs will be readable for a thousand years, based on the expectation that the polycarbonate layer (the same polycarbonate layer shared by all CDs) should last a thousand years, but that the data layer, which they say is “Rock-like” (but of secret composition) is permanent as long as it’s protected by the polycarbonate layer. Hey, it’s not some kind of “rock-like” metal.

But it doesn’t matter: they go a step further, test their media with other recordable media, and come out ahead. Of note is the lack of a test against manufactured CDs.

How long do normal optical discs last?

Depending on the dye used, the lifespan of a recordable CD or DVD is typically 10 to 100 years.

Kodak testing indicates that “with 95% confidence, 95% of the population of KODAK Recordable CD media will have a data life of more than 217 years when stored in the dark at 25°C, with 40% relative humidity after recording on a KODAK PCD Writer 200”.

But that durability changes based on its exposure to heat, ultraviolet light, moisture, and possibly other environmental considerations. As a result, although media can be expected to last ten years (or 217), a portion of recordable CDs fail after 3 to 5 years. Most manufacturers claim a shelf life of 5-10 years.

How long does a pre-recorded CD last?

The Council on Library and Information Resources (CLIR.org), a stakeholder in reliable data storage, says that expectations range from 20 to 100 years for these drives. They also say there is a consensus among manufacturers of recordable CDs and DVDs that CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more under recommended storage conditions and be rewritable ( CD-RW, DVD-RW, DVD+RW and DVD-RAM) must have a life expectancy of 25 years or more.

M-Disc claims a useful life of 1,000 years.

Now, having data that lasts a thousand years (like books stored in the best conditions) is great. But what about the ability to read the disks in a thousand years?

CD-ROM drives became popular around 1983. Although they were a bit expensive, they could store around 700 MB of data. About 5 years later, drives that could write to recordable CD discs were commercially released, and these drives became popular later in the 1990s. DVDs hit the market around 1996 and could hold around 4.6GB of data , more than six times more data in the same space as a CD. In 1997 DVD-R was released, allowing users to burn their own DVDs. One I bought around the year 2000 cost me around $2000. As of this writing (post-2011), such a drive is listed for around $40. A dual-layer DVD that can hold twice as much as a standard DVD was commercially available as of 2005 and a new dual layer DVD burner can be had today for around $50. Blu-Ray was released commercially in 2006, and one disc can hold 50 GB of data and a Blu-Ray burner can be bought today for around $120 .

The moral of this part of the story is that formats change.

We are looking for ever larger and faster storage in ever smaller and less expensive forms of media. CDs were a dominant form of optical media storage for about 15 years, roughly the practical lifespan of the media. DVDs became the dominant way of life for optical media, but incompatible improvements occurred within ten years. DVD is expected to last 15 or 20 years, close enough to the expected life of a disc. We’ve only had dual-layer Blu-Ray and DVD for a few years now and I’m guessing they’ll be gone in another ten years.

I myself am trying to unload a cabinet full of removable media drives. There are various optical, magneto-optical, tape, and other removable magnetic media drives, such as Zip disk, Syquest, and others. For more than a decade, I have offered a service of transferring data from an old format to something currently readable. For the last five years, that part of my business has disappeared. I have tried selling these units on eBay and other vendors and there is no market for them. There is only one niche market and vendors of such devices don’t seem to be able to download them either. I can’t give them away! Many of these are newer formats than CD and some are newer than DVD. At one time, some of these formats were almost standard and were ubiquitous as backup devices.

It is laudable that the Millenniata have created a form of writable communication medium that they claim will last a thousand years. Your media surely seems to be more durable than other optical media. But what’s driving the technology is (as I mentioned before) ever-increasing storage, ever-faster storage on ever-smaller, less-expensive forms of media. Millenniata is coming out of the gate with slower, more expensive media using (presumably) more expensive drives. If the history of technology is any guide, these drives and media will not become a standard and will have a lifespan much shorter than 15 years. In something like ten years, these media may be as easily viewable and readable as 8mm film is today. In a hundred years, no one will know what they are, let alone a thousand.

With their great YouTube videos and a logo that I love, I think these will make a short but exciting little splash. It’s great that they can withstand being slammed against a table or submerged in liquid nitrogen, but how many of us have this problem? The ExtremeTech website is certainly very enthusiastic about them “M-Disc is a DVD made of stone that lasts 1,000 years” but in the end it draws a conclusion much the same as mine.

The M-Disc is a good idea, but ultimately it’s not much more useful than the faster and more capable media and technology already on the market for less. If this is their only product, the discs can be found intact hundreds of years from now, but I’m not so sure the company is.