Today, Micron announced that its shipping the industry’s first QLC (quad-level cell) NAND SSD, starting immediately. That’s a surprising move, for two reasons. First, for many years it wasn’t even clear if QLC NAND could ever be built. While TLC NAND first started shipping some years ago, the problems with TLC’s introduction on planar NAND (exemplified by drives like the Samsung 840 EVO), meant that TLC didn’t really come into its own until the introduction of 3D NAND and the use of older process nodes to build the drives (40nm 3D NAND, compared with 20nm planar NAND). Secondly, when TLC arrived, it arrived in consumer products first, only later taking the jump to enterprise products.
Micron, in contrast, is taking the leap for enterprise first, and planning a consumer introduction later.
As we’ve previously discussed, there’s an inverse relationship between the number of program/erase cycles a drive can withstand and the number of bits it can hold per cell. The more bits per cell, the greater the number of voltage levels, and the more difficult it is to read data back properly. This tends to slow down the drive’s write performance and reduces overall longevity.
While Micron isn’t giving us much information on the specific capabilities of the 5210 Ion, it was willing to discuss the overall market for the drive in more detail. The Ion brand is specifically designed for drives with read-heavy workloads that’ll perform minimal writes — and it’s also intended for enterprise deployments, where the performance of QLC SSDs will still represent a significant improvement over hard drives.
One interesting point Micron made to me when we spoke was that the endurance needs of SSDs are actually decreasing, in many areas, rather than increasing. At first glance, this might seem counterintuitive. After all, the amount of data we collectively create each year has been growing for years. As it turns out, however, more advanced operating systems that return more data on how much data is actually written to drives per day in enterprise deployments has shown that the number of writes is lower, in some cases, than was previously thought.
Meanwhile, rapid growth in SSD capacities has meant that drives, generally speaking, are now much larger than they once were. This naturally decreases the number of drive writes per day that are practically going to be performed. We even referenced this idea earlier this year, when we noted that Nimbus’ 100TB SSD is so huge, you literally can’t perform one drive write per day if you assume that the SSD maintains its maximum rated transfer speed 24 hours per day.
When you put these trends together, you’ve got a potentially large market for SSDs in industries that have historically still been using HDDs, or might only be using SSDs for caching. The Ion 5210 QLC isn’t expected to replace TLC drives, but to serve as an adjunct to them, offering better than hard drive performance; significantly higher drive capacities, thanks to the 1.33x improvement in data stored per-cell; and a better overall price tag compared with MLC or TLC drives over the long term. Micron isn’t sharing more details than that at the moment, but the company has stated that it expects to give more information later this year.