The M-Disc: durable but possibly doomed

11-06-2021

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

How they did it?

Commercially produced and prerecorded CDs and DVDs are based on a series of pits (holes) and surfaces (not holes) molded into the disc’s bottom transparent polycarbonate 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.

Both DVDs and CDs are a type of optical disc, as the data is read optically by laser light.

The holes are in the upper part of the polycarbonate layer, which in turn is covered by a layer of shiny metal, to reflect the laser. There is a coat of lacquer to protect the gloss coat and then (sometimes) artwork on top.

Recordable discs have much the same construction, but instead of recesses molded into the polycarbonate layer, there is a layer that contains a photosensitive dye, with the thin reflective layer of metal on top. The laser writes on the disc changing the color of the dye. The unit reads the difference in reflectivity of the tint instead of the holes.

The new Disc M uses a laser to etch holes in the etchable layer, instead of changing the color of a tint. Then the laser reads the reflectivity difference of the media on 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 illuminated by a laser.

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 that all CDs share) should last a thousand years, but that the data layer, which they say is ” rock-like “(but secret in composition) is permanent as long as it is protected by the polycarbonate layer. Hey, isn’t metal something “stone-like”?

But it doesn’t matter: they go one step further, test their media against other recordable media and take the lead. Of note is the lack of evidence against manufactured CDs.

How long do normal optical discs last?

Depending on the dye used, the lifespan of a recordable CD or DVD is generally estimated to be between 10 and 100 years.

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

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

How long is a prerecorded CD?

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 disks. They also say that there is a consensus among recordable CD and DVD manufacturers that CD-R, DVD-R, and DVD + R discs should have a life expectancy of 100 to 200 years or more under recommended, rewritable storage conditions ( CD- RW, DVD-RW, DVD + RW, and DVD-RAM discs) 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 kept in top condition) is great. But what about the ability to read the discs in a thousand years?

CD-ROM players became popular around 1983. Although they were a bit expensive, they could hold around 700 MB of data. About 5 years later, drives that could write to recordable CDs were released commercially, and these drives became popular later in the 1990s. DVDs hit the market around 1996 and could hold about 4.6 GB of data. , more than six times more data in the same space as a CD. DVD-R was released in 1997, allowing users to burn their own DVDs. One that I bought around the year 2000 cost me around $ 2000. At the time of writing (later in 2011), such a unit is trading for around $ 40. A double layer DVD that can hold twice as much that a standard DVD was released from 2005 and today you can get a new double layer DVD burner for about $ 50. Blu-Ray was released commercially in 2006, and a disc can hold 50GB of data and today you can buy a Blu-Ray burner for about $ 120.

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

We are looking for ever faster storage on ever smaller and less expensive media. CDs were a dominant form of optical media storage for about 15 years, roughly the practical lifespan of media. DVDs became the way of life for mainstream optical media, but incompatible improvements were made within ten years. The DVD is expected to last 15-20 years, close enough to the expected lifespan of a disc. We’ve had Blu-Ray and dual-layer DVDs for only a few years now and I suppose a phasing out in another ten years.

I myself am trying to unload an enclosure 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 offered a data transfer service from an old format to something readable today. In 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 a niche market and the vendors of such devices don’t seem to be able to get rid of 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 close to standards and ubiquitous as backup devices.

It is commendable that Millenniata has created a form of writing medium that, according to them, will last a thousand years. Your media surely appear to be more durable than other optical media. But what’s driving the technology (as I mentioned before) is ever-increasing storage, ever-faster storage in ever smaller and less expensive forms of media. Millenniata is coming out the door with slower, more expensive media that use (presumably) more expensive drives. If the history of technology is any guide, these units and media will not become a standard and will last much less than 15 years. In about ten years, these media can be seen and read as easily as 8mm film is today. In a hundred years no one will know what they are, much less a thousand.

With their great YouTube videos and a logo that I love, I think they’ll make for a short, but exciting little touch. It’s great that they can withstand being beaten on a table or dipped in liquid nitrogen, but how many of us actually 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 like mine.

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