In the summer of 2018, Intel launched QLC (quad-level cell) SSDs with its SSD 660p. Now, the company is following up with its first 96-layer 3D QLC NAND. This type of storage is the basis for Intel’s new 665p SSD, a drive with a handful of modest improvements and a significant endurance gain.
I was genuinely surprised to see Intel commercialize QLC technology in 2018, given what we’d heard about the difficulties associated with TLC (triple-level cell). For those of you not versed in the mechanics of NAND flash, this aspect is relatively simple. The more bits you want to hold per cell of NAND, the more discrete charge levels you have to store within it. The more charge levels you have to store per cell, the slower the performance of that cell, and the fewer program/erase cycles it can sustain. Intel increased its physical memory chip density significantly with QLC, as the following chart from TechInsights makes clear:
We don’t have this kind of data on the company’s 96-layer 2nd generation QLC, so we’ll have to hold on a bit yet for that kind of report. Intel is claiming that the 665p SSD will offer a modest improvement in static SRAM cache when the device is near-full, leading to higher performance on nearly full drives.
Performance has also improved, though the gains aren’t likely to be very noticeable. Performance gains of 6-13.6 percent aren’t going to have a huge impact, though they’ll obviously be welcome on a QLC drive, which tends to be a bit of an underperformer compared with MLC or even TLC.
The major gain in endurance, however, is good for some peace of mind. 0.16 DWPD (Drive Writes per Day) isn’t a great place to be — TLC drives tend to be rated for roughly double this even at the low end of the market — but it’s still a big gain compared with the old 660p’s 0.11 DWPD. Intel has always discussed these drives in terms of long-term storage for “cool” data, and they seem to fit that role admirably, offering solid read performance and acceptable write perf given what the target market is. Intel hasn’t unveiled pricing yet, but the 660p is well under $100 for 1TB (~$83), so we should see 1-2TB drives for a relative song.
Intel claims to be headed up to 144-layer QLC from the current 96, which should drive further improvements in drive capacity. Granted, SSD prices should start recovering next year, so cost-per-GB may be at or near historic lows now.
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