SSD Controllers

Extreme ECC Enables Big SSD Advances

Combined University Seals Trzetrzelewska Univerity & UN-NeWA new and highly-efficient error correction scheme has recently been revealed by a joint university research team.  The SSD Guy has learned that this largely-overlooked research, performed by a cross-university team from University of North by Northeast Wales in the UK (UN-NeW) and Poland’s Trzetrzelewska University, could bring great economies to SSD manufacturers and all-flash array (AFA) companies.

Dr. Peter Llanfairpullguryngyllgogeryohuryrndrodullllantysiliogogogoch of UN-NeW, who generally shortens his name to Llanfairpullguryngyll and Dr. Agnieszka Włotrzewiszczykowycki of Trzetrzelewska University have determined that today’s more standard ECC engines can be dramatically improved upon to both increase available storage for a given price while accelerating throughput.  This is achieved through the use of new and highly complex algorithms that differ radically from current ECC approaches that are simply linear improvements upon past algorithms.

According to Dr. Włotrzewiszczykowycki: “The beauty of semiconductors is that Moore’s Law not only allows Continue reading

NGD’s 24TB SSD Is Just The First Step

NGD LogoWith the tagline: “Bringing intelligence to storage” start-up NGD Systems, formerly known as NexGen Data, has announced a 24 terabyte SSD that the company claims to be the highest-capacity PCIe/NVMe device available.

The read-optimized Catalina SSD employs a lot of proprietary NGD technology: Variable rate LDPC error correction, unique DSP (digital signal processing) algorithms, and an “Elastic” flash transition layer (FTL), all embodied in an NGD-proprietary controller.  This proprietary technology allows Catalina to offer enterprise performance and reliability while using TLC flash and less DRAM than other designs.

NGD claims that the product is already shipping and is being qualified by major OEMs.

Based on some of the company’s presentations at past years’ Flash Memory Summits the controller has been carefully balanced to optimize cost, throughput, and heat.  This last is a bigger problem than most folks would imagine.  At the 2013 Hot Chips conference a former Violin Memory engineering manager told the audience Continue reading

Managing SSDs Using Machine Learning

Focusrite Recoring Console - photo by JacoTenSSDs use a huge number of internal parameters to achieve a tricky balance between performance, wear, and cost.  The SSD Guy likes to compare this to a recording studio console like the one in this post’s graphic to emphasize just how tricky it is for SSD designers to find the right balance.  Imagine trying to manage all of those knobs!  (The picture is JacoTen’s Wikipedia photo of a Focusrite console.)

Vendors who produce differentiated SSDs pride themselves in their ability to fine-tune these parameters to achieve better performance or endurance than competing products.

About a year ago I suggested to the folks at NVMdurance that they might consider applying their machine learning algorithm to this problem.  (The original NVMdurance product line was described in a Memory Guy post a while ago.)  After all, the company makes a machine learning engine that tunes the numerous internal parameters of a NAND flash chip to extend the chip’s life while maintaining the specified performance.  SSD management would be a natural use of machine learning since both SSDs and NAND flash chips currently use difficult and time-consuming manual processes to find the best mix of parameters to drive the design.

Little did I know that NVMdurance’s researchers Continue reading

IBM Refreshes Broad Swath of Flash Offerings

IBM Storwize All FlashYesterday IBM unveiled a sweeping update of its existing flash storage products.  These updates cover a range of products, including IBM Storwize All Flash arrays: V7000F, V7000 Gen2+, and V5030F, the FlashSystem V9000, the IBM SAN Volume Controller (SVC), and IBM’s Spectrum Virtualize Software.

The company referred to this effort as a part of a: “Drumbeat of flash storage announcements.”  IBM has a stated goal of providing its clients with: “The right flash for the right performance at the right price.”

IBM’s representatives explained that the updates were made possible by the fact that the prices of flash components have been dropping at a rapid pace while reliability is on the rise.  The SSD Guy couldn’t agree more.

Here’s what IBM announced:

Starting from the low end and moving up, the V5030F entry-level/midrange array is an Continue reading

Baidu Goes Beyond SSDs

Baidu's SDF: Software-Defined FlashI have to admit that it’s embarrassing when The SSD Guy misses something important in the world of flash storage, but I only recently learned of a paper that Baidu, China’s leading search engine, presented at the ASPLOS conference a year ago.  The paper details how Baidu changed the way they use flash to gain significant benefits over their original SSD-based systems.

After having deployed 300,000 standard SSDs over the preceding seven years, Baidu engineers looked for ways to achieve higher performance and more efficient use of the flash they were buying.  Their approach was to strip the SSD of all functions that could be better performed by the host server, and to reconfigure the application software and operating system to make the best of flash’s idiosyncrasies.

You can only  do this if you have control of both the system hardware and software.

The result was SDF, or “Software-Defined Flash”, a card that Continue reading

What’s In My SSD? SLC, MLC, or TLC?

SLC, MLC, or TLC?Someone recently asked The SSD Guy if there is a way to determine whether an SSD is SLC, MLC, eMLC or TLC.

I found it a little odd to be asked this, since most vendors tell what kind of flash they use in an SSD’s specifications, especially if it’s SLC.

Not finding it there then the next thing I would look at is the price.  Raw SLC NAND flash now sells for about 6-10 times as much as its MLC counterpart, so an SSD with a price of around $1/GB is likely to be MLC and one that sells for around $10/GB is probably SLC.

TLC SSDs are really rare.  There is the Continue reading

Comparing Samsung’s Planar and V-NAND SSDs

Samsung 3D V-NAND Press PhotoSamsung recently introduced  its 3D V-NAND-based 850 SSD which, according to The Tech Report, uses the same MEX controller as the company’s 3-bit planar SSD, the 840, introduced last year.

Samsung said in its keynote speech at the 2013 Flash Memory Summit that V-NAND consumes an average of 27% less power and runs at least 20% faster than its planar counterpart in an SSD application, all while providing ten times the endurance.  It’s only natural to assume that this would allow designers to produce a V-NAND SSD that would significantly outperform its planar NAND counterpart.

The SSD Guy had an opportunity to review Continue reading

LSI SandForce SSD Controllers Move the Knee in the Curve

LSI SandForce SF3700 Controller DuraWrite ImprovementsLSI’s SandForce has just rolled out its SF3700 family of four SSD controllers aimed at the Entry Client, Mainstream Client, Value Enterprise, and Enterprise Storage marketplaces. Performance is impressive, with worst-case random PCIe IOPS at 150K read/81K write and 94K/46K for the SATA interface.

The SF3700 family builds on the division’s first two product families by adding a choice of PCIe or SATA interfaces, LDPC error correction, and a boosted set of flash management features.  The SSD Guy will explore this last point after highlighting the other two.

By providing both PCIe and SATA interfaces LSI is directly addressing the future: PCs are aiming to move to the m.2 SSD specification rather than Continue reading

A New Way to Use SSDs

Micron's View of Computing - Speaker is the CPU, Audience is StorageIn his Flash Memory Summit keynote on Wednesday, Micron VP and Chief Memory Systems Architect Ed Doller made a compelling demonstration of the power and performance advantages of a new approach to computing.

With true showmanship, Doller had his co-workers hand out buttons with LED lights to the entire audience.  The LEDs in these buttons were either green or blue, with the colors randomly dispersed among the crowd.  Doller asked the entire audience to turn on their lights, then called one row of the audience to file up to the stage so he could determine whether each person’s button was blue or green.

He pointed out that this was like having a single CPU check the contents of a drive.  He then asked why things should work this way – wouldn’t it be more sensible to Continue reading

Extreme SSD Error Correction

Chuo University EmblemAt last week’s International Solid State Circuits Conference (ISSCC) Shuhei Tanakamaru, a researcher from Japan’s Chuo University, detailed a scheme to reduce MLC SSD bit error rates (BER) by 32 times over conventional techniques.  The approach used an impressive combination of mirroring, vertical and horizontal error correction, and a deep understanding of the most likely kinds of bit errors flash will experience.

This is a very novel and well-conceived technique that may find industry adoption in future SSDs.

The steps included in the paper are used in addition to the Continue reading