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A new storage technology unveiled this month holds the promise of as many as 500 terabytes of data being stored on a glass disc about the size of a CD, but how broadly it can be used is uncertain.
In a paper published by the Optica Society, researchers at the University of Southampton in the U.K. write that they created a new method for using a laser to write data onto glass — fused silica — that enables a massive amount of data to be stored on an optical disc.
This would give organizations the ability to hold the data — as much as 10,000 times more data than can be stored on a Blu-ray disc — for long periods of time on manageable and portable medium. They were able to accomplish this by using a laser to etch dots onto glass by sending a pulse every femtosecond (a quadrillionth of a second).
The Five Dimensions
The five-dimensional aspect refers to the use of two optical dimensions — the intensity of light and polarization and the changes made to them by the dots — and the typical three spatial dimensions used in traditional storage.
5D storage isn’t new. It’s been around for several years, with University of Southampton researchers making breakthroughs as early as 2016. The 5D crystal data storage technology was dubbed “Superman memory crystals,” a reference to crystals in the movie “Superman” from 1978. It was seen as a way to store large amounts of data on a medium that offered longer life and more capacity than tape storage.
It also comes as the industry is continuing to evolve, with the rise of flash storage and SSDs and the inroads being made in such areas as computational storage.
Long-Term Storage
The amount of data that can be stored on the disc is not the only substantial number. According to researchers, the data on a 5D could still be readable after 13.8 billion years and could survive temperatures as hot as 1,000 degrees Celsius without degrading.
However, there were problems. In particular, the technology was hindered by slow writing speeds, which made it impractical for most purposes.
“With the slow write speed, this is best for long-term storage, which has been problematic, because tape, used for long-term storage, does not have an unlimited storage life and can be adversely impacted by the environment where it is stored,” Rob Enderle, principal analyst with The Enderle Group, told Enterprise Storage Forum. “It is vulnerable to magnetic fields, which come from significant solar events.”
The industry has “been exploring multi-dimensional glass storage for some time,” Enderle said. “It appears viable. The issue has been the read and write speed that makes it unacceptable for any online storage application and historically too long for repository use.”
Speed is the Issue
The challenge has been the speed the laser moved. If it moved too quickly, it could hamper the disc’s structure, reducing its usefulness. However, doctoral researcher Yuhao Lei and his collaborators at the University of Southampton say in their paper that they solved that issue.
They did this by using the femtosecond laser with a high repetition rate. In addition, they didn’t use the laser to write directly in the glass. Instead, they used a phenomenon call near-field enhancement, which essentially uses a few weak light pulses to create tiny structures called nanovoids, small nanostructures in the glass.
After trial and error, they were able to find a laser pulse at the right speed and power level that could accelerate the writing, while minimizing the thermal damage to the glass disc. According to their paper, the researchers were able to hit a maximum data rate of 1 million voxels per second, which equals a data rate of about 230 kilobytes per second. The accelerated write speed made it possible to fill in a disc that has a capacity of about 500 TB, a process that would take about two months.
The speed could be increased through the use of parallel writing, with multiple laser beams writing on the glass disc.
Tests Show Promise
Tests found that through the new technique, the researchers were able to write 5 gigabytes of data onto a silica glass disc with as much as 99.5% accuracy, which could be pushed to 100% through the use of an error-correction algorithm.
Right now, the 5D storage technology could best be used for data that needs to be kept for long periods of time, Enderle said.
“This technology would favor anything that requires long-term storage, like ownership documents, documents that define a protected product, legal requirements — government documents, for instance — medical research [and] DNA analysis of species that are becoming extinct,” Enderle said. “But this is ideal for any data type that needs to be recorded long-term but does not require real-time access and is set in history and not dynamically changing over time.”
Broader commercial use would depend on accelerating the write and read speeds. The slow speeds currently limit how the technology could be used.
In addition, if the technology does become viable for commercial use, organizations will have to be careful about how it’s used and who uses it.
“This kind of media would be ideal for anyone wanting to steal data in large quantities and have access to the hardware,” Enderle said. “Think [Edward] Snowden on steroids. The write speed limits this, but an employee could pull the data slowly over time and then remove the medium. But as write speeds increase, the viability of this storage medium for data theft will increase substantially.”
