Attemps to improve error correction for QLC

China's main control technology provider Maxio Tech recently announced the successful development of the 4K LDPC algorithm. This is the first time that domestic SSD control chip manufacturers have achieved continuous breakthroughs in this technology, which will greatly improve the reliability and service life of QLC flash memory.

https://cntechpost.com/2020/04/15/chinese-firm-says-its-new-algorithm-greatly-improves-reliability-of-qlc-flash-memory/

So, last night I decided to move some files to my M.2 NVMe QLC drive. I was using it for video caching, so smallish files in general. All was good. I was moving massive 4K DNx files. About 300GB. First few seconds 1400MB/s. "Pretty nice for a cheap drive!". Less than 40 seconds later 185MB/s "Ah, what a pain, but still faster than my magnetic drive". A while later I come back speed about 38MB/s. "OK, this is not OK, this is shit"... ... .... A while later I come back 14MB/s "WTF, that is literallly 1% of the initial speed!". I left and went to sleep at that point, but unless something changes massively, that is the last QLC drive I buy. Not that I was not warned, but yeah, the drive is only good for small files, that's a fact.

8TB QLC NVMe drive (expected sustained write speed 40-80Mb.sec)

At the write speeds that I got from my QLC drive when transferring a big file (225 gigs of video), I do understand the push for servers. If you do not care about noise, magnetic platters still seem more cost effective (if slower for small operations).

Yeah, my post should have said "I do not understand". My drive between the temperature increase and the cache being done was writing at less than 10MB per second. I have very old SD cards that are faster than that.

QLC comes

Major chipmakers are ramping up their quad-level cell (QLC) NAND flash output, SSDs utilizing the technology storing four bits per cell have become commercially available and are set to soon penetrate at a faster pace into the markets for both enterprise- and consumer-class storage devices, according to industry sources.

The adoption of QLC NAND-based SSDs has been rising for datacenter and other enterprise-class storage applications since 2020, the sources said. QLC SSDs are more demanded for high-capacity and lower-cost SATA storage devices, in particular.

Phison offers its new S12DC controller for a 15.36TB QLC-based enterprise SATA SSD, with sample deliveries already kicking off. In a statement issued by Phison, market research firm TrendFocus indicated "the enterprise SSD market will maintain greater than 10 million units per year for a number of years out. Enterprise and datacenter customers looking for high capacity, lower cost SATA storage solutions will have a very viable option with this high capacity QLC-based solution."

QLC helps drive a more approachable price point, narrowing the affordability gap between HDDs and solid state storage, noted Micron, which claimed the company is the first to make QLC technology available in an enterprise-class SSD.

WD seriously think about using HDD for SSD caching

WD will work on special software driver to cache large amount of sustainable writing for QLC and PLC disks as they will fully replace TLC in consumer devices during 2021.

After dynamic SLC cache of SSD disk will be full, driver will be able to use other SSD and even HDD to cache writes (content will be written in the hidden files) and will later slowly move data to target SSD drive.

QLC sustainable write speed is normally in 14-60Mb/sec and PLC speeds are expected to be in the range of 4-2-Mb/sec. So, using HDD becomes reasonable.

Micron Technology has begun volume shipments of what the company claims is the world's first 176-layer 3D NAND flash memory.

Micron indicated its new 176-layer technology and advanced architecture represent a radical breakthrough enabling immense gains in application performance across a range of storage use cases spanning data center, intelligent edge and mobile devices.

"Micron's 176-layer NAND sets a new bar for the industry, with a layer count that is almost 40% higher than our nearest competitor's," said Scott DeBoer, executive VP of technology and products at Micron. "Combined with Micron's CMOS-under-array architecture, this technology sustains Micron's industry cost leadership."

Adding more layers is the only improvements vector for now.

Micron slide

More recent Intel QLC state

Major NAND flash chip suppliers are poised to ramp up their output for QLC (quad-level cell) NAND chips between the end of this year and 2022, eyeing robust demand for not only PCs but also datacenter applications

Micron announced the start of shipments of 232-layer 3D NAND TLC flash memory chips, which have the highest density on the market - the volume of a single chip can reach 1 Tbit. In addition to significantly increased density, the new 232-layer 3D NAND TLC flash chips offer up to two times faster write speeds and up to 75% faster read speeds than previous generation chips.