What is a 3D SSD?

Some SSDs, particularly Western Digital and Sandisk-branded drives, have the words “3D SSD” on the label. This isn’t purely a marketing term. But what is a 3D SSD, exactly?

What is a 3D SSD? It refers to the manufacturing process of the wafer.
3D NAND refers to how many layers of memory the manufacturer stacks onto a silicon wafer like this one prior to slicing it into individual chips.

What is a 3D SSD?

“3D” refers to the process the chip manufacturer used on the memory chips inside the drive. It allows the manufacturer to stack cells within a single chip, increasing speed and capacity while lowering cost.

So should you buy a 3D SSD? Sure. But it’s not the only thing to consider. The number of layers matters. The controller chip in the drive also matters. How well all of the parts work together also matters. To really make sure you’re getting the best SSD for the money, look at the random I/O speed, especially write speed. Manufacturers generally measure this in IOPS at this point. Higher is better.

This process isn’t especially new at this point. Micron, Intel, Toshiba, Hynix, and Western Digital all posess 3D technology at this point. The difference is how many layers they can stack. Unless it’s old inventory, any new SSD on the market today can rightfully claim itself as a 3D SSD. Some companies make a bigger deal of pointing it out than others.

Manufacturing processes as branding

What is a 3D SSD? You can't tell by looking.
Nothing about a 3D SSD’s outward appearance distinguishes it from a drive built on an earlier memory technology.

Advertising your manufacturing process isn’t especially new. In the early 1990s, some brands of computers briefly placed the acronym VLSI on their cases. VLSI stood for “very large scale integration.” It drove down cost, allowed for the computers to be smaller, and theoretically at least, it improved reliability. Eventually consumers started to take VLSI for granted. Today’s computers utilize VLSI on a scale we couldn’t even imagine in the 1990s, but nobody talks about it anymore. Marketers tout any technological advantage they can, real or perceived, for as long as it works.

Eventually the same thing will happen with 3D NAND flash. It will become normal, and nobody will talk about 3D SSDs anymore. That will be the end of the question of what is a 3D SSD. By then, some other new technology will undoubtedly take its place. One potential replacement technology is something Intel and Micron call 3D Xpoint. HP has been working on another potential replacement, Memristor, for several years now.

In the hyper-competitive SSD market, changes come quickly. The benefit is lower prices and higher performance for us.

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