At the Flash Memory Summit in California, Samsung has unveiled what appears to be the world’s largest hard drive—and somewhat surprisingly, it uses NAND flash chips rather than spinning platters. The rather boringly named PM1633a, which is being targeted at the enterprise market, manages to cram almost 16 terabytes into a 2.5-inch SSD package. By comparison, the largest conventional hard drives made by Seagate and Western Digital currently max out at 8 or 10TB.
The secret sauce behind Samsung’s 16TB SSD is the company’s new 256Gbit (32GB) NAND flash die; twice the capacity of 128Gbit NAND dies that were commercialised by various chip makers last year. To reach such an astonishing density, Samsung has managed to cram 48 layers of 3-bits-per-cell (TLC) 3D V-NAND into a single die. This is up from 24 layers in 2013, and then 36 layers in 2014.
Historically, like most computer chips, NAND flash has been planar—that is, the functional structures on the chip are (for the most part), laid down on a single two-dimensional plane. In a similar way to how logic chips are moving towards 3D transistors (FinFETs), Samsung (and more recently Toshiba and Intel) has been forging ahead with 3D NAND.
The simplest way of describing 3D NAND is that everything is turned on its side: so instead of having just one layer of memory cells on a single plane, you can now have dozens of layers of cells, all standing up next to each other. (The “V” in Samsung’s V-NAND refers to the vertical nature of these cells.) Process-wise, 3D NAND is very complex, but the massive potential density increase makes it worthwhile.
The 16-terabyte drive (actual capacity 15.36TB) must use between 480 and 500 of Samsung’s new 256Gbit dies. We’re not entirely sure how you squeeze that many dies into a standard 2.5-inch SSD case, but presumably there’s some die or package stacking involved.
At the Flash Memory Summit, as reported by Golem.de, Samsung showed off a server with 48 of these new SSDs, with a total storage capacity of 768 terabytes and performance rated at 2,000,000 IOPS (input/output operations per second). By comparison, the consumer-grade SSD that you have in your PC is probably capable of around 10,000-90,000 IOPS, depending on the workload.