How long can computer storage really last?
Researchers from the University of Twente (Holland) developed a new storage medium made of tungsten embedded in a matrix of silicon nitride and potentially lasting for more than a million years. This medium could serve as long term data storage, to preserve humanity’s achievements for future generations.
Humans have performed data storage since prehistoric times. Although the storage techniques have changed immensely with time, the idea was the same, i.e. storing useful information/data, for the use and knowledge of future generations.
In the last fifty years, in particular, technological development greatly increased device storage capacity. The first commercial hard discs (1956), for instance, had 24 inch dimensions and a storage capacity of 5 MB; at present, 3.5 inch hard discs with 4 TB storage capacity are available.
Data Duration Over Time
Despite the progress made in this field, one critical problem of storage media is their duration over time. The expected lifetime of computer hard discs, for instance, is about ten years. Over longer times, in fact, the discs lose the magnetic properties essential for data storage.
Different mediums are available for longer term storage; archival grade DVDs, for instance, can survive for as long as 100 years. Paper archives can also last hundreds of years, but only in special protected conditions (i.e. in an environment with no extreme temperature changes and relatively low humidity).
There is a great interest in the development of longer lasting storage mediums that do not require particular protection.
Researchers from the University of Twente (Holland) developed a new storage device which could, in principle, last as long as one million years. Dr. Jeroen de Vries researched this as part of his PhD studies and published the results in his PhD thesis on the 17th of October 2013.
The device is made of tungsten (W), embedded into silicon nitride (Si3N4).
Humanity Achievement Legacy
Dr. de Vries explains to Decoded Science:
“The idea behind this project is that humanity produced many things which are worth storing; art, literature, music or scientific inventions are just some examples. When, eventually, humanity will cease to exist, these things will disappear as well, unless we store them in a device which can last for millions of years and outlive humanity. The ‘Human Document Project’ is a multidisciplinary project dealing with this, about what we can leave to the world, after our disappearance.
In my PhD thesis I focused on the development of a device which could be used for long-term storage and contribute to leave a legacy of human history and development.”
Simple Data Storage Device
The researchers kept the device as simple as possible for fabrication purposes but also to produce something relatively easy to read and decode.
Both specifically-chosen materials comprising the device are very hard (and hence resistant) and have a relatively small thermal expansion coefficient.
The figure on the side shows the storage medium; the data storage and reading is based on the optical properties of the material. With tungsten, light beams undergo destructive interference; with Si3N4, on the contrary, there is constructive interference.
“To test the device, we used a two-dimensional matrix barcode, the Quick Response (QR) code; this can be read by computers or smart phones.” Dr. de Vries said.
Calculation of Expected Life Time
To determine how long this device could last, Dr. de Vries and his coworkers made some theoretical calculations based on a mathematical model; this took into account the characteristics of the materials and their stability with time, temperature, etc.
According to Dr. de Vries:
“In the calculations we made, we used the Arrhenius-based model; it is simple but it can give us a first idea about the expected life time of the storage medium. According to our results, the device should last millions of years. Moreover, it is very resistant to extreme conditions, such as high temperatures, fire, etc. For instance, we used the disc to bake an egg, and it was still working after it.”
In the video below, you can see some of tests made on the storage medium and how it survived all these tests; they were made by Mr. Dimitri Schellenberg, a student from the same university who also worked in the project.
So, is this the perfect storage medium? According to Dr. de Vries:
“The only drawback is that this system is not rewritable. For long term storage, however, this should not be a problem. In fact we expect that the information to be stored for the Human Document Project will be carefully selected and will not need to be changed. This approach is generally referred to as Write-Once-Read-Many (WORM).”
Dr. de Vries plans to continue to work on the system to optimize it further. Perfect data storage that lasts forever? Perhaps just another project away.
De Vries, J. Energy barriers in patterned media. (2013). University of Twente. Accessed November 10, 2013.
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