By Michael Fitzpatrick
BBC News

You might be familiar with the heartbreak and frustration of a failed hard disk – fretting over the loss of precious pictures, irreplaceable files squirreled away over years, often lost forever.

These are depressingly regular losses often visited on those who do not make regular back-ups. According to one report by Swedish data salvaging service Kabooza that is the majority of us.

A massive 82% of home computer users hardly bother with back-ups, says its worldwide report.

But no matter how much you back up, all that precious data could be easily wiped out or rendered unreadable in the future anyway because of out-of-date or redundant technology.

Just think of those large sized floppy disks we used only a couple of decades ago, now inaccessible to all but the early PC enthusiasts.

So imagine the headache archivists face having to figure a way to back up and preserve our digitised heritage and make it accessible for future generations – even 1,000 years into the future – and avoid what many dread: a digital Dark Age.

‘Future imperative’

Researchers working in Japan say they might have the breakthrough archivists are praying for – a sealed permanent memory bank that will be easily readable now and far into the next millennium.

"Archiving the mountains of digitalised cultural heritage we have amassed for the future is paramount"

Professor Kuroda

The team, led by Professor Tadahiro Kuroda of Tokyo’s Keio University, has proposed storing data on semiconductor memory-chips made of what he describes as the most stable material on the Earth – silicon.

Tightly sealed, powered and read wirelessly, such a device, he claims, would yield its digital secrets even after 1000 years, making any stored information as resilient as it were set in stone itself.

It’s a realisation that moved the researchers to name the disc-like, 15in (38cm) wide device the "Digital Rosetta Stone" after the revolutionary 2,200-year-old Egyptian original unearthed by Napoleon’s army.

"Archiving the mountains of digitalized cultural heritage we have amassed for the future is paramount," says Professor Kuroda.

One project – The World Digital Library (WDLP) has its sights on such a device.

WDLP aims to provide online access to significant cultural material from around the world for free.

According to Professor Kuroda the project needs a device that can last at least 1,000 years, more than a terabyte of storage and real-time accessibility.

"We believe our sealed permanent memory system, the Digital Rosetta Stone, will satisfy these demands."

Work on this silicon lifebelt is still at an experimental stage, but Professor Kuroda hopes to have something ready for practical use in ten years.

So far his team has managed to read and write more digitised data onto the "stone" than found in the vast British Library collection.

The process starts by etching bits and bytes by laser onto silicon wafers, the ultrapure materials from which computer chips are made.

Crucially, the nature of these digital markings will be determined by a universal agreement on a common storage language that will hopefully last thousands of years. That is yet to come says Kuroda.

These are stacked on top of one another to form a 10cm- (4in-)high disk, which is sealed between layers of another type of near-impregnable silicon to keep out oxygen and moisture.

According to the professor, these are the two culprits that will render seemingly durable CDs and DVDs into unreadable ornaments in the next 30 to 100 years.

Set in stone

There is some debate about just how long these forms of plastic disc storage can last.

But a recent study by the Optical Storage Technology Association (OSTA), which spent two years testing DVD and CD discs to evaluate their life expectancies, found that both DVD-R and CD-R could maintain data for tens of years at most.

CDs had a life expectancy of only around 15 years whilst DVDs fared even worse with a lifespan of around 10 years.

"It’s such a poor rate when you consider books can last hundreds of years," says Professor Kuroda.

Other common storage devices also perform poorly in terms of longevity and universal readability.

In the case of magnetic hard drives – those commonly found in PCs – data could be lost in four to 40 years owing to the influence of magnetic fields.

But with semiconductor devices, claims Professor Kuroda, data can be kept intact for a thousand years or more if the humidity around the chip is kept at 2% or less.

Others are also trying to ensure that when future generations attempt to look back on the dawning of the digital age, they are not staring into a dark void.

The US Storage Networking Industry Association (SNIA) is committed to solving digital preservation problems, but admits it is a challenge to design and build a digital archive that would last even just 100 years.

"Be it in solid state technology, biomechanical, and other nano-technological formats, we now realise that most of our archiving for future generations will be in digital formats, and we are here to support development in both hardware and software in these areas," says the SNIA’s Rick Bauer.

But nothing has appeared as a front runner so far, he says.

As the association’s leading technologist, he says he has been impressed with the Digital Rosetta Stone.

However, despite Prof. Kuroda’s claims, such a storage device still faces a huge hurdle, he says.

Silicon-based or otherwise, such a medium is still up against the digital data archivists’ arch enemy: magnetic polarity.

Constant fluctuations in the Earth’s magnetic field wreck havoc with electromagnetic storage devices such as hard drives, which encode data in magnetic charges.

"We’ll have to solve the changes in magnetic polarity in written storage media that happen over the years," he says.

"Right now, we are seeing polarity degradation after 10 years, which would affect the stability and reliability of the data, however it’s written."

After a few decades dedicated to our new love affair with all things digital it seems we still have a long way to go to beat the lasting power of stone records and even those on paper.

Analogue certainly hasn’t had its day, and the search for a truly long-lived and readable digital Rosetta Stone goes on.</p

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