Mirror images: why glass might be the future of data storage

Mirror images: why glass might be the future of data storage

Over the past decade, entrusting our photos and files to Big Tech’s cloud has become such a part of daily life that we barely have to think about it. Services such as Dropbox, iCloud and Google Photos silently scoop our data up from our phones, into the ether.

Yet maintaining the data centres that store all this information is far from effortless. In addition to building, powering and cooling these vast facilities, the physical media on which the data are stored requires constant attention. A hard disk drive, similar to those found in a desktop PC, usually needs to be replaced every three to five years, while tape — which is still widely used for archival storage and takes much longer to copy — can degrade over several years.

With extra storage capacity being added all the time, tending to all that storage has become an increasing burden for cloud computing providers.
Now Microsoft is declaring a breakthrough in an entirely new storage format: glass. Unlike tape or a hard drive, glass storage could last for hundreds or thousands of years. It does not degrade and is resistant to data corruption — known as “bit rot” — from heat, floods or even solar flares, which can sometimes affect magnetic storage.

Project Silica, which is developed by Microsoft Research in Cambridge in partnership with the University of Southhampton, is a three-year-old attempt to develop storage for the requirements of cloud computing, rather than personal devices.

“If we start from scratch and find something suitable for the cloud . . . you can think about everything on a completely different scale,” said Ant Rowstron, principal researcher and deputy lab director at Microsoft Research Cambridge. “We had concluded that we have done everything we could do with the current [server] racks and the current storage media.”

In early November, Microsoft and Warner Bros demonstrated Project Silica by storing the 1978 movie Superman on a 7.5cm by 7.5cm slab of glass — far smaller than the spools of celluloid on which the studio preserves its archives today. Microsoft has also tested it out by putting the code base for Windows 10 on to a 2.5cm by 2.5cm piece of quartz glass.

This technology is only starting to become possible today thanks to improvements in infrared lasers. So-called “femtosecond” lasers, similar to those used in laser eye surgery, are much faster and more precise. If a laser pulse is too large and powerful, it might crack the glass. Project Silica’s technique builds up dozens of layers of data into the glass on “voxels” — similar to a three-dimensional pixel. Mr Rowstron likened them to icebergs that sit within the glass itself.

The data are then “read” by shining light, at a variety of polarisations, through the glass. Machine learning algorithms can make this process much faster than spooling through tape storage to find the right data.
Thursday, 15 November, 2018
There are still barriers to scaling the technology up to cloud-wide deployments. Each piece of glass can only be written once, so the format is not reusable like hard drives are. And it is a slow process. Embedding a single two-hour movie such as Superman into the glass can take days, Mr Rowstron said. “But three years ago, it would have taken months to years,” he added. “Now we understand it, it’s easier to think about how to speed it up.”

Mirror images: why glass might be the future of data storage

It is also much more expensive than existing storage systems, largely because of the cost of the lasers themselves. And while storage density remains low today, researchers at Southampton believe that a DVD-sized piece of glass could eventually hold 360 terabytes of information.
But despite the seeming fragility of glass, Mr Rowstron is confident that in the coming years, Silica will eventually turn into a durable new form of storage. Lack of sensitivity to environmental influences could even make data centres less resource-intensive, by lowering the requirements for cooling and power that today make cloud computing a significant part of the tech industry’s environmental impact.

“To destroy the data, the glass would need to be ground up into a powder or melted at 1400 degrees Celsius,” Mr Rowstron said. “If it breaks into shards, the data will still be within the glass.”