Chinese team’s memory leap shrinks data centre storage capacity into DVD-sized disk

“This technology makes it possible to achieve exabit-level storage by stacking nanoscale disks into arrays, which is essential in big data centres with limited space,” the team wrote in an article published in the peer-reviewed journal Nature on Thursday.

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The scientists are from the University of Shanghai for Science and Technology, Peking University, as well as the Shanghai Institute of Optics and Fine Mechanics and Key Laboratory of Photochemistry, both under the Chinese Academy of Sciences.

In data storage units, 1,024 gigabytes equal 1 terabyte, and 1,024 terabytes form 1 petabit, while 1,024 petabytes make up 1 exabit.

The global data volume is projected to reach 175 zettabytes by 2025, according to global market intelligence provider International Data Corporation. One zettabyte is 1 trillion gigabytes.

Optical data storage (ODS) is a light-based storage method commonly used in DVDs. It is cost-efficient and durable, but its capacity is limited since it usually stores data in a single layer.

In the new study, the Chinese team said they created a three-dimensional architecture to store data across hundreds of layers instead of one, resulting in optical data storage capacity reaching the petabit level for the first time ever.

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The layers of the disk were just 1 micrometre apart, allowing it to remain as thin as a regular DVD. The scientists wrote and read the data using laser beams.

“The ODS has a capacity of up to 1.6 [petabits] for a DVD-sized disk area through the recording of 100 layers on both sides of our ultrathin single disk,” the researchers said, adding that it can store 24 times the data of today’s most advanced hard disk drives.

“It will thus become possible to build an exabit-level data centre inside a room instead of a stadium-sized space by stacking 1,000 petabit-level nanoscale disks together … resulting in a large number of cost-effective exabit data centres.”

Existing data centres require vast amounts of energy to operate, while internal devices generate immense heat, which requires even more power for cooling.

The International Energy Agency estimated that data centres across the world consumed about 1 per cent of total global electricity demand in 2022.

In China, the National Energy Administration said the total electricity consumption by the country’s data centres was 270 billion kilowatt-hours in 2022, almost triple the amount of power generated in the same year by the Three Gorges hydropower stations – the world’s largest power-generating facility. The consumption totalled about 3 per cent of China’s total electricity usage.

The team said the new technology could minimise the need for data migration, a tricky process that data centres must perform every three to 10 years, putting data at risk of tampering or loss.

One of the corresponding authors, Wen Jing, a professor from the University of Shanghai for Science and Technology, said the new technology would provide more energy-efficient data storage.

“Energy will only be needed when data is written onto or read from the disk, but not when storing data, thanks to the inherent properties of ODS,” Wen said.

“The disks are also highly stable so there are no special storage requirements. The new disk is expected to last 50 to 100 years, unlike a hard disk drive which requires data to be moved to a new device every five to 10 years,” she said.

Hard disk drives can also fail due to physical damage, such as being dropped or exposed to excessive humidity.

Wen said the new disks could someday allow individuals and families to set up their own databases with minimal fuss.

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“It used to take a lot of space and investment to operate a database. But in the future, families could keep a disk to store a large amount of photos, videos and documents instead of saving them on many separate external hard disk drives,” she said.

While the production workflow of the new disks is compatible with existing DVD technology, Wen said the team will continue to improve the speed and reduce the energy needed to write and read data from the disk.

They will also work to make the device for accessing data on the disk more affordable, in hopes of making it commercially available in the near future, she said.

South China Morning Post