The manufacturer Western Digital has found a new way to overcome the barrier of 20 TB on its hard drives. He has just announced a new architecture, called OptiNAND, which combines flash memory with a traditional system of magnetic plates. Western Digital insists that these are not hybrid models (SSHD) where flash memory is used to store the data most often used.
In the case of the OptiNAND architecture, an iNAND UFS flash memory chip stores a large amount of metadata (several GB depending on the manufacturer) that are essential for the hard disk to function properly. It can also be used in the event of a power failure, to temporarily store user data that could not be written to the disk (more than 100 MB). Storing metadata in flash memory has two advantages: freeing up disk space and increasing performance, with faster access. In contrast, Western Digital does not indicate the amount of flash memory that is used in the architecture.
The manufacturer has produced samples of 20 TB disks that use this new architecture. Composed of nine trays of approximately 2.2 TB, they benefit from a helium filling (HelioSeal), to have less friction than air. They also employ ePMR technology, which is an evolution of perpendicular recording, used in consumer hard drives. This technology is part of the EAMR (Energy Assisted Magnetic Recording) category, which also includes the HAMR process chosen by Seagate.
Already present in the manufacturer’s 16TB and 18TB Gold models, it uses additional current in the read head to reduce disturbance during magnetic recording. It is thus possible to increase the recording density.
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Finally, the samples are equipped with read / write heads with a triple positioning system (TSA) to increase precision.
Western Digital has not yet specified when these new types of hard drives will be released to the market. The only certainty is that they will be primarily intended for businesses, for example for data centers.
Source : Western Digital