Sony claims areal density record for magnetic tape storage
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Sony has successfully developed magnetic tape technology that allows data to be stored with an areal density of 148Gbit/in2. This is said to be some 74 times the capacity of current mainstream coated magnetic tape storage media and could enable more than 185Tbyte to be stored in a standard LTO Ultrium format data cartridge.
The advance has been made through the development of a tape with a soft nano grained magnetic layer with fine magnetic particles and a uniform crystalline orientation.
To create the tape, Sony developed a vacuum thin film forming technology which forms fine crystal particles. This approach uses sputter deposition to generate multiple layers of crystals with a uniform orientation on a polymer film less than 5µm thick. Sony said that when the sputter method was used previously to deposit fine magnetic particles on a polymer film, roughness on the surface of the soft magnetic underlayer resulted in non uniform orientation of the crystals in the layer above, preventing increases in recording density.
By optimising sputter conditions and developing a soft magnetic underlayer with a smooth interface, Sony has created a nano grained magnetic layer of fine magnetic particles with an average size of 7.7nm.
Sony says it will now work towards commercialising the technology and developing advanced thin layer deposition technologies to further increase areal densities.
IBM assisted Sony in the development process by measuring and assessing the recording density. In 2010, IBM Research's Zurich laboratory, working with Fujifilm, created a system that could store data at an areal density of 29.5Gbit/in2. At the time, it claimed this might enable data cartridges that could store up to 35Tbyte of uncompressed data. This, it said, would be sufficient to store the text of 35million books, which would require 400km of shelving.
A data storage pioneer, IBM launched the 726 (pictured) in 1952. This used an oxide coated non metallic tape approximately 12mm wide. Information was recorded on the tape in six channels that ran parallel to the length of the tape. A seventh channel monitored reading and writing of the other six channels using an odd number redundancy check.
The tape could store 100bit per linear inch, or 2.3Mbyte for the two 1200ft and two 200ft reels supplied as standard with the 726, which weighed 935lb.
