Western Digital introduces new non-SMR 20TB HDDs with onboard NAND

Enlarge / This isn't Western Digital's first 20TB drive-but it is the first shipping drive to achieve that density without the use of Shingled Magnetic Recording (SMR) technology. (credit: Western Digital)

At Western Digital's HDD Reimagine Event yesterday, the company introduced its newest hard drive architecture-a hybrid spinning rust/NAND flash design it calls OptiNAND. But as WD President of Technology and Strategy Dr. Siva Sivaram told Ars in an interview, OptiNAND bears almost no resemblance to the much-maligned hybrid SSHD drives first introduced in 2011 and 2012.

Instead of promising SSD-like speeds via caching of customer data, OptiNAND offers increased areal density by removing firmware-accessible metadata from the disk itself and storing it on NAND instead.

20TB per disk without SMR

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  Like last year's 20TB SMR drives, the OptiNAND drives employ EAMR in the form of an additional current to the main pole of the write head. [credit: Western Digital ]

The most tangible milestone achieved by Western Digital's newly announced architecture is a nine-platter, 20TB drive that does not require Shingled Magnetic Recording (SMR) techniques. The new disk uses a subset of Western Digital's EAMR technology, which has been rebranded ePMR-presumably to emphasize that it's not SMR, which has severe performance and usability implications for many common workloads.

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