The Bleak Future of NAND Flash Memory

Vitaliy_Kiselev

In recent years, flash-based SSDs have grown enormously both in capacity and popularity. In highperformance enterprise storage applications, accelerating adoption of SSDs is predicated on the ability of manufacturers to deliver performance that far exceeds disks while closing the gap in cost per gigabyte. However, while flash density continues to improve, other metrics such as a reliability, endurance, and performance are all declining. As a result, building larger-capacity flashbased SSDs that are reliable enough to be useful in enterprise settings and high-performance enough to justify their cost will become challenging. In this work, we present our empirical data collected from 45 flash chips from 6 manufacturers and examine the performance trends for these raw flash devices as flash scales down in feature size. We use this analysis to predict the performance and cost characteristics of future SSDs. We show that future gains in density will come at significant drops in performance and reliability. As a result, SSD manufacturers and users will face a tough choice in trading off between cost, performance, capacity and reliability.

The technology trends we have described put SSDs in an unusual position for a cutting-edge technology: SSDs will continue to improve by some metrics (notably density and cost per bit), but everything else about them is poised to get worse. This makes the future of SSDs cloudy: While the growing capacity of SSDs and high IOP rates will make them attractive in many applications, the reduction in performance that is necessary to increase capacity while keeping costs in check may make it difficult for SSDs to scale as a viable technology for some applications.

Via: http://cseweb.ucsd.edu/users/swanson/papers/FAST2012BleakFlash.pdf

Vitaliy_Kiselev

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.

Vitaliy_Kiselev

Apple is working with multiple NAND flash chipmakers to develop cost-effective QLC (quad-level cell) NAND flash solutions, and could adopt the memory in its iPhone series as early as 2022.

It will be very sad day. Especially for video guys.

Vitaliy_Kiselev

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

Vitaliy_Kiselev

During the event dedicated to Samsung's Q2 financial results, company representatives talked about their progress on 200-layer V-NAND flash memory chips. These will be the first chips of this kind in the entire industry.

Han Jin-man, senior vice president and curator of Samsung's memory division, said that the company has already developed 200-layer (and this number may still grow) eighth generation V-NAND memory chips, which are currently being prepared. launch of a production line to bring them to the market. “176-layer chips will remain the mainstream NAND product until 2022. And, according to the approved 10-year plan, we are working on the next generation V-NAND chip. "

Progress is slowing down as lot of layers is also not good and very prone to errors.

Vitaliy_Kiselev

More recent Intel QLC state

Vitaliy_Kiselev

Another cheap QLC drive writing speed

Vitaliy_Kiselev

Micron slide

Vitaliy_Kiselev

Hynix also present 176-layer tech

SK Hynix has developed what the company claims is the industry's most multilayered 176-layer 512Gb triple-level cell (TLC) 4D NAND flash, and started delivering the chip samples to controller companies recently.

SK Hynix noted it has been promoting 4D technology from the 96-layer NAND flash products that combine the company's in-house developed charge trap flash (CTF) with high-integrated peri under cell (PUC) technology. The new 176-layer NAND flash is the company's third-generation 4D product, which delivers a 35% improvement in bit productivity when compared to the previous generation. The read speed of cell increased by 20% over the previous generation adopting 2-division cell array selection technology, while the data transfer speed has been improved by 33% to 1.6Gbps adopting speed-up technology without increasing the number of processes.

Starting with mobile solution products that have improved maximum read speed by 70% and maximum write speed by 35% in mid 2021, SK Hynix plans to release consumer and enterprise SSDs sequentially expanding its application market of the products.

SK Hynix also has plans to develop one terabit (Tb) products with doubled density based on 176-layer 4D NAND.

Vitaliy_Kiselev

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.

Vitaliy_Kiselev

1TB QLC writing speed chart if disk is free, but not trimmed and zero filled

Horror.

Vitaliy_Kiselev

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.

Vitaliy_Kiselev

Xbox and Playstation will use only QLC memory

Main idea of Microsoft and Sony is that by having special protected SSD drives that you can't replace they could limit effective life of game consoles. QLC is known for quick degradation even in case if you do not write too much in the NAND chips.

Vitaliy_Kiselev

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.

Vitaliy_Kiselev

Dangerous signs from Intel

arum

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.

Vitaliy_Kiselev

@arum

HDDs are actually faster at linear write speeds than most consumer QLC drives (if you measure areas out of SLC cache).

arum

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).

Vitaliy_Kiselev

Bad news coming

The adoption of QLC (4bits/cell) NAND memory is set to grow rapidly starting the second half of 2020, thanks to rising demand for data-intensive applications demanding large-capacity, efficient and cost-effective storage, according to industry source.

Vitaliy_Kiselev

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

Vitaliy_Kiselev

@arum

Do not worry, companies plan to already have around 60-70% QLC only consumer drives this fall.

This time it will be silent move, no fanfares.

Same as with MLC before it 3D TLC will remain in premium drives during 2021 and especially 2020.

arum

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.

Vitaliy_Kiselev

Roadmaps

Vitaliy_Kiselev

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/

Vitaliy_Kiselev

The spread of the coronavirus pandemic has dragged down considerably shipments for most end products in the first quarter of 2020, and can lead to cut of NAND flash bit output this year to about 30%.

Vitaliy_Kiselev

Micron news and QLC

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