this is the home page of
20 years - leading the way to the new storage frontier .....
image shows megabyte waving the winners trophy - there are over 200 SSD oems - which ones matter? - click to read article
top SSD companies ..
SSD news since 1998
SSD news ..
SSD SoCs controllers
SSD controllers ..
Rackmount SSDs click for news and directory
rackmount SSDs ..
military storage directory and news
military SSDs ..
click here for storage market research directory
market reports ..
pcie  SSDs - click to read article
PCIe SSDs ..
M.2 SSDs ..

Contact us:

fastest SSDs
storage reliability
ratios in SSD architecture
11 Key Symmetries in SSD design
adaptive R/W and DSP ECC in flash SSDs

classic SSDs from SSD market history
Foremay Immortal Military SSD.  - click for more info
Aerospace, Military, and Industrial grade
rugged SSD drives by Foremay, Inc.,
Secure erase, Encryption
Learn more about - Foremay
Integrated with multiple patented and patent pending technologies, the Immortal series solid state drives are designed to work in extreme environmental conditions in military, defense, aerospace, and submerged applications  Military grade SSDs from Foremay

1.0" SSDs
1.8" SSDs
2.5" SSDs
3.5" SSDs

1973 - 2018 - the SSD story

2013 - SSD market changes
2014 - SSD market changes
2015 - SSD market changes
2016 - SSD market changes
2017 - SSD market changes
2018 - SSD market changes

20K RPM HDDs? - SSD killed RPM

About the publisher - 1991 to 2018
Adaptive R/W flash IP + DSP ECC
Acquired SSD companies
Acquired storage companies
Advertising on
Analysts - SSD market
Analysts - storage market
Animal Brands in the storage market
Architecture - network storage
Articles - SSD
Auto tiering SSDs

Bad block management in flash SSDs
Benchmarks - SSD - can your trust them?
Big market picture of SSDs
Bookmarks from SSD leaders
Branding Strategies in the SSD market

Chips - storage interface
Chips - SSD on a chip & DOMs
Click rates - SSD banner ads
Cloud with SSDs inside
Consolidation trends in the enterprise flash market
Consumer SSDs
Controller chips for SSDs
Cost of SSDs

Data recovery for flash SSDs?
DIMM wars in the SSD market
Disk sanitizers
DRAM (lots of stories)
DRAM remembers
DWPD - examples from the market

Efficiency - comparing SSD designs
Encryption - impacts in notebook SSDs
Endurance - in flash SSDs
enterprise flash SSDs history
enterprise flash array market - segmentation
enterprise SSD story - plot complications
EOL SSDs - issues for buyers

FITs (failures in time) & SSDs
Fast purge / erase SSDs
Fastest SSDs
Flash Memory

Garbage Collection and other SSD jargon

Hard drives
High availability enterprise SSDs
History of data storage
History of disk to disk backup
History of the SPARC systems market
History of SSD market
Hold up capacitors in military SSDs
hybrid DIMMs
hybrid drives
hybrid storage arrays

Iceberg syndrome - SSD capacity you don't see
Imprinting the brain of the SSD
Industrial SSDs
Industry trade associations (ORGs)
IOPS in flash SSDs

Jargon - flash SSD

Legacy vs New Dynasty - enterprise SSDs
Limericks about flash endurance

M.2 SSDs
Market research (all storage)
Marketing Views
Memory Channel SSDs
Memory Defined Software - yes really
Mice and storage
Military storage

Notebook SSDs - timeline

Optical storage drives

Petabyte SSD roadmap
Power loss - sudden in SSDs
Power, Speed and Strength in SSD brands
PR agencies - storage and SSD
Processors in SSD controllers

Rackmount SSDs
RAID systems (incl RAIC RAISE etc)
RAM cache ratios in flash SSDs
RAM memory chips
RAM SSDs versus Flash SSDs
Ratios in SSD design architecture
Razzle dazzling flash care
Reliability - SSD / storage
RPM and hard drive spin speeds

SCSI SSDs - legacy parallel
Symmetry in SSD design

Tape libraries

Test Equipment
Top 20 SSD companies
Tuning SANs with SSDs

USB storage
User Value Propositions for SSDs

VCs in SSDs
VCs in storage - 2000 to 2012
Videos - about SSDs

Zsolt Kerekes - (editor linkedin)

animal brands in SSD
The SSD market isn't scared of mice.

But mice aren't the only animals you can find in SSD brands.

There are many other examples of animal brands in SSD as you can see in this collected article.

And before the SSD market became the most important factor in the storage market there were also many animals to be found in other types of storage too.
.. is published by ACSL founded in 1991.

© 1992 to 2018 all rights reserved.

Editor's note:- I currently talk to more than 600 makers of SSDs and another 100 or so companies which are closely enmeshed around the SSD ecosphere.

Most of these SSD companies (but by no means all) are profiled here on the mouse site.

I still learn about new SSD companies every week, including many in stealth mode. If you're interested in the growing big picture of the SSD market canvass - StorageSearch will help you along the way.

Many SSD company CEOs read our site too - and say they value our thought leading SSD content - even when we say something that's not always comfortable to hear. I hope you'll find it it useful too.

Privacy policies.

We never compile email lists from this web site, not for our own use nor anyone else's, and we never ask you to log-in to read any of our own content on this web site. We don't do pop-ups or pop-unders nor blocker ads and we don't place cookies in your computer. We've been publishing on the web since 1996 and these have always been the principles we adhere to.

SSD Year 2018?

3 things which have already happened and 1 which hasn't yet

by Zsolt Kerekes, editor - - November 12, 2018
. Megabyte's winter red hat
at this time of year Megabyte sets aside
more time for reading and re-reading
articles about SSDs
Is there an easy way to summarize the main developments in the SSD market of 2018 already?

In past years such articles have been publishable from around the start of November. And with a few cosmetic edits those past summaries have generally withstood the test of time.

But the closing months of the calendar aren't as non eventful as that suggests - and every now and again - vendors have used the news snooze of the holidays to perform acquisitions.

Here are some examples.
  • December 2012 - Samsung acquired NVELO (a flash caching software company).
  • December 2013 - LSI agreed to be acquired by Avago Technologies.
  • December 2018 - this hasn't happened yet - and is the "1" which I referred to in my headline
So on the subject of writing year end summaries of the SSD market - it's more accurate to say that - generally in recent years - it has been possible to capture all the major trends in such articles before all 12 months had elapsed. And looking ahead - if there isn't an acquisition story in the December 2018 news - then you should watch out for a note of one having been quietly done in January 2019.

So - what can we say did happen in SSD Year 2018?

For the essential month by month details you can see the SSD news archive pages below.
SSD Year 2018 - month by month
January February March April May June
July August September October November December
But I didn't need to revisit any those pages to write my shortlist - of 3 things - which goes likes this.

3 things in SSD year 2018

1 - international trade barriers

In 2018 - the free flow of memory and SSD products between the US and China which had characterized business trends since the start of the modern era of SSDs - came to an end.

A growing set of patent disputes, government embargoes and the background worldwide babble of trade wars (related to other countries - not just involving the US and China - and related to other types of products too) created market conditions for memory and SSD companies in which the mood of doing business in 2019/2020 is expected to be different to how things had worked before.

Will this affect prices?

We saw the SSD market survive and thrive when the costs of memory doubled during the 2017 memory shortages. Set against that market robustness and expectations of falling prices again (the way they used to be) - then I think tariff barriers won't have a damaging effect on prices.

Will trade barriers affect SSD company prospects?

Yes - but it's a mixed picture.

Sme companies (whose business models leveraged the freedom of micro managing international differences in the costs of assembling products) will see initial setbacks and will have to redraw their supply chain maps.

On the other hand - there will be new opportunities for smaller companies arising from a trading climate in which there is more local protection from locked out dominant international competitors..

And companies which operate outside the disputed hot spots - will see opportunities to service markets in which they would have been uncompetitive before.

2 - memory cost outlook

In the 4th quarter of 2018 - the imbalance between supply and demand of traditional memory products (nand flash and DRAM) which had for 2 years flipped the price per bit curve outlook upwards from its historically established downwards direction - looked like it was getting ready to flip back again - according to price trends being reported by leading market reporters.

Looked at in isolation - it would be reasonable to expect that the memory industry's ability to ship more products in 2019 - than it could when still dealing with the overhang of yield issues related to the structural switch away from the last significant generation of 2D scaling - would inevitably lead towards expectations of lower prices.

However - the impact of trade wars introduces new variables into the cost outlook for memory systems.

The interplay between the industry's ability to manufacture traditional memory products - compared to the growing difficulties of legally shipping them into traditional geographic markets will create a rich vein of source material for SSD bloggers in 2019.

3 - memory defined processing

Because standards organizations have traditionally taken so long to say anything meaningful about the past disruptive trends in the modern era of SSDs (such as the gap between the proprietary PCIe SSD market invasion of the server market and its taming by the unifying language of NVMe) you know that when a standards ORG intervenes in this market - then something has really happened.

So in 2018 when SNIA said it was interested in getting involved in talks about taming the computational storage market - then that was another one of those things.

But a problem for the industry - which hasn't been solved yet in 2018 - is what to call this thing.

I 've touched upon it each time a news story has appeared on these pages and the SSD jargon page includes some (but by no means all) the examples which have been used by various companies which have implemented products.
  • in-situ processing
  • processing in memory
  • computational storage
  • in-memory computing (historically means something different - but is starting to sound like its meaning should change)
This is one of those subjects - like the original adoption of SSDs - about which we already know a lot - except what to call it.

It intersects with many other top level views of memoryfication architecture.

You can describe it as one of the eleven SSD design symmetries - specifically - "adaptive intelligence flow symmetry".

Or you can say it's a variation of the data industry's creative use of controllernomics - whereby any data whose latency is beyond the here and now in this chip - whether due to media speeds or distance and the speed of light - requires a local intelligent agent which can do useful things at our remote bidding.

But the concept still lacks a universally agreed name.

And by "universal" I mean a term which is usable whether the memory is an SSD or RAM array - and whether the local intelligence is an SSD controller, FPGA, ASIC or other acceleration engine.

In my headline above - I used the words "memory defined processing". I wasn't being provocative in offering that. I don't think it will stick. But real concepts need acceptible words. And just as memory defined software was a temporary placeholder in a blog for a real market concept - even if the words seem as if they are in the wrong places. I think that 2018 is the year that the concept of memory defined processing was crying out for a better name than it had received so far.

See also:- 2018 timeline and permalink for this article

strategic bifurcations in SSD market history

4 ways to split SSD history into "before and after" to understand now

by Zsolt Kerekes, editor - - October 29, 2018
. click for bigger image and more about Spellabyte's software factory
we're going to add the comments
to the source code later
When I published the first version of my popular article Charting the Rise of the SSD Market in October 2004 it wasn't the long rambling messily formatted historical narrative which you see today.

In 2004 I and my readers in the SSD market had already lit the fuse for the market explosion which I predicted would inevitably follow - based on a market adoption and "why buy SSDs" user value propositions which were completely different to anything which the industry had thought about before.

I was too busy then changing all my plans to reduce my editorial coverage of all other storage subjects to focus all my energies on the SSD market. I was more interested in the future than the past. And I wondered if I'd be able to keep up with tracking market and making a difference to it.
So in 2006 when when I was looking ahead at my predictions about the growing number of SSD companies which no one had heard of (and which would need a new series called the Top SSD Companies) I realized that SSDs was a market without a reliably written history.

How would newcomers understand it? And we needed those newcomers to make the market work. And they as early adopters were already facing a big barrier of challenging intertwined technical issues in processors, memory, storage and software which was did not have any clear centralized ownership.

Due to my past experience with another growing market before that - SPARC systems - the quickest way to write the first draft of history is to repurpose news stories you've already written into a simple timeline. So in October 2006 my charting the rise of the SSD market article was repurposed to look a bit like the history article today. You can see that version here.

And after that quick and dirty first version of SSD market history (based on what I had experienced first hand) I continued to be busy writing about current and forward looking stuff. So my history article just became a dumping ground for adding more stories each year.

It also became a fertile source from which other publications extracted timelines and sometimes entire clumps of text. Irritating for me that so few acknowledged what their source was - but hey that's the internet.

interpeting SSD history on a rolling basis

Something which every market analyst and editor does at many times in their working lives (if they're any good is to try and interpret for their readers how news stories relate to the emerging market context. That's how we get all those end of year "looking back" and predictive "looking foward" articles which seasonally become increasingly common as December draws nearer.

I was doing exactly the same kind of thing and in some years I would confidently assert "this will be or has been the year of such and such important emerging trend".

So I added those into my history article too.

And because I care about authenticity (and because I was simply short of time) I just cut and pasted those present tense analyses into the growing narrative - whether they were right or wrong - was another matter.

Which is how we get to this point here.

As I'm retiring from such active involvement in the SSD market in 2019 (which may already have happened by the time you read this) I was looking back at SSD history and asking myself - is there a story which I can wrap around the past 40 years of rambling anecdotes and an interpretation which might help a modern reader to appreciate what happened - without having to know all the details?

That was my eureka moment - when I realized - I've been doing the same kind of thing to explain SSD controller architectures, and memory caching ratios and design symmetries etc for many years. And technology experts who know far more than me about what goes on inside semiconductors and systems have told me they found my simple splits of architecture into different sets have been handy ways of thinking about stuff.

So how to split SSD history?

Here are my 4 proposed strategic splits.

split 1

before and after the Modern Era of SSDs

Before the Modern Era - the enterprise SSD market wasn't a sticky market.

After the Modern Era - it was.

And the only thing likely to replace an enterprise SSD was another SSD or memory system.

In my article celebrating the first decade of the Modern Era of SSDs I placed the tipping point at around 2003.

Before the Modern Era - even if an end user had deployed SSD accelerators to fix performance problems in one key application the balance of probability was that for future applications the users would turn back again to legacy solutions such as faster clocked servers and storage. But those legacy options stopped getting faster in a series of steps:-
  • server processor makers had begun telling me in 2000 that future clock speeds couldn't keep growing in the same kind of way which had been an associated assumption of semiconductor design shrinks and Moore's Law since the start of the microprocessor era.

    For processors this aspect of Moore's Law (incrementally faster clock speeds) broke in 2000 to 2003.

    I wrote about this problem in a spoof article April 1, 2002 - HotServer Technologies Announces the 3GHz hotSPARC 9000 and more strogly later - Why Sun Should Acquire an SSD Company (May 2004) in the SPARC Product Directory.

    I didn't realize in 2000 that clock speeds would stay at the same kind of speed limits for the next 20 years.

    But the good thing about the failure of these legacy markets to deliver ever faster solutions was it forced more people to look at SSDs - despite the steep initial learning curves involved.

split 2

before and after Fusion-io

In September 2007 - Fusion-io launched the ioDrive - a PCIe form factor flash SSD with upto 640GB capacity and 100K IOPS performance.

That event created the PCIe SSD market which soon after became a key focal point for innovations in enterprise SSD architecture and SSD systems software due to the combined efforts of the many competitors which entered that market.

There are many strands of SSD market history associated with Fusion-io. In this article about strategic bifurcations I'm just going to mention 2 of them.

SSDs became must-have options in server product lines

Before 2009 - when Fusion-io began announcing a series of design wins for its ioDrives in enterprise servers made by HP, IBM and Dell - big server manufacturers didn't offer SSD accelerators as standard options in their product ranges.

After these initial design wins - it became imperative for all server manufacturers to offer an SSD solution embedded in future products if they wanted them to look competitive. (This tipping point - if one does it they'll all have to do it - was predicted in my 2003 article - could enterprise SSDs become a $10 Billion Market?)

the strategic importance of SSD software

Before Fusion-io there wasn't an SSD software ecosystem. And the lack of automatic software tools for integrating SSDs into caching and other acceleration roles meant that deploying SSDs as accelerators required expensive and skilled manual hot spot tuning.

One of the spin offs from the standardization of SSD integration in servers was that it inspired a wave of SSD software startups which had never been viable before.

Most of the early SSD software pioneers were acquired by SSD manufacturers as the market learned that having compatible software for virtualization and caching made it much easier to sell their SSDs.

Although it's hard to believe it now - this was still a time when there was a vacuum in the space where the SSD software brain might have been expected to be in the vision of legacy giants in the enterprise software, processor chip and array storage markets - who were all taken completely by surprise by this new industry.

split 3

before and after Diablo Technologies' Memory1

Diablo Technologies was a pioneer in shipping SSDs and DRAM emulation products which consisted of flash memory and controller IP integrated in a DRAM compatible DDR3 or DDR4 bus slot.

Although Diablo's products failed to achieve any significant market traction and the company was involved in a series of patent disputes and went bankrupt - there were important market lessons to be learned from the outcome of what I called in August 2015 the first salvo of SCM (Storage Class Memory) DIMM Wars.

Before Diablo's Memory1 (announcement, shipping and customer benchmarks) there had been a genuine belief in the SSD industry that new types of non volatile memory memory products shipped in DRAM compatible bus slots would plausibly launch the next wave of performance improvements in the server market - in a similar way that the PCIe SSDs had done earlier - and that somehow - the latency differences of these 2 types of busses and the ability to place more emulated memory in server motherboards would make an order of magnitude difference and help to create substantial new markets.

The immediate effect of the Memory1 announcement was to set off a spate of competitor announcements about NVDIMM based products aiming at the same idea but based on a variety of design approaches and memory technologies (not just flash).

After the market failure of Memory1 my analysis of the SCM DIMM wars phenomenon is that the architectural promise of such products was fatally flawed and delivered marginal incremental benefits sometimes rather than sustainable order of magnitude improvements of the types promised by the initial hype.

The main reasons for the past failure and future limitations of such products are (in my view) the misconception that a single component type of solution is in itself enough to take computing performance to a sufficiently high next level - compared to the comparison point of an already sophisticated SSD infrastructure.

Instead - what I call the "memoryfication" of enterprise computing - at the next level of performance will require changes in processor, memory and software architectures working together in new conceptual schemes.

And I think such solutions will be agnostic with respect to form factors and may not indeed look anything like a DIMM. Indeed they may work just as well delivered in PCIe slots (like Google's TPU) or be implemented at rack scale in fabrics.

I've discussed these ideas in a bunch of articles including:-

optimizing CPUs for use with SSDs
introducing Memory Defined Software
RAM in the post modernist SSD and Memoryfication Era
should we expect more from memory? - after AFA's what's next
are we ready for infinitely faster RAM? (what would it be worth)

split 4

before and after the memory shortages in 2017

Although the silicon based semiconductor memory industry had experienced many periods of under supply and over supply capacity since its formation - the shortages of nand flash and DRAM which began in the 2nd half of 2016 and lasted through to the first half of 2018 were like no other which had happened before - in strategic impact and lasting consequences.

Before the memory shortages of 2017 - there had been a bunch of non volatile memories which (in some cases for more than a decade) had failed to ever emerge into sticky design wins and market adoption from their seemingly never ending "emerging" status - due to their lagging too many years behind successive improvements in mainstream memory pricing per bit.

During the memory shortages - the effect of rising prices in flash and DRAM and the realization that those legacy memory roadmaps could no longer be relied on to follow the historic expectations set by past experiences were beneficial to the competitive comparisons with emerging competing nvms. It was as if the emerging nvms had got into a time machine and emerged looking 2-4 years better.

After the memory shortages of 2017 - it became clear that (as I phrased it in a 2017 article) "new notes had been added to the music of memory tiering. And while we still can't be sure which of these "no longer emerging but emerged" memories will have lasting power in the memory and SSD markets - it is clear that a significant change had occurred and (for a forseeable bunch of years) there is no going back to the just 2 main types of memory model for future SSD designers and memoryfication architects. Memory designs will change. Processor designs will change. Architecture will change to incorporate the capabilities of new types of memory.

A much longer list of market impacts can be seen in my article - miscellaneous consequences of the 2017 memory shortages.

The causes and analysis of market events leading up to the shortages along with contemporaneous commentaries can be seen in the news archives of and other historic web sites which discussed the memory and SSD markets at that time.

split 5, 6, 7, 8, 9, 10...

insert your own here

I'm sure that many of you having reached this point may be wondering - why didn't I mention a particular thing which you believe is just as important as those above.

I'd like to think that having written so many articles about SSDs - maybe I already did write about some of those other things before. But if I didn't - then I'm sorry. I'm glad I finished this one. It's the last main article about SSDs I'll be writing about SSDs this side of retirement. (Or maybe ever.)

Thanks for reading it.

And if it's given you some ideas - then that's what I was hoping.

Here's a very old article I feel proud to have written.

why buy SSDs? - pioneering use value propositions

Bye for now and take care.

SSD ad - click for more info


perceptions of the data recovery market

by Zsolt Kerekes, editor - - September 14, 2018
What's the connection between fast erase SSDs, storage drive sanitization and data recovery?

It was the recent news about the hurricane season which got me thinking again (as it does every year) about all those tragic stories of damage and loss.

The data recovery industry is unlike other parts of the computer market because no one sets out with the idea that they want to include DR technology in their annual storage budgets.

I thought back to some of the stories of amazing data survival and recovery which I've reported on in my writings here.

Drives being soaked in mud (that's one thing) - drives being drenched in chlorine (including the backups) that was another.
Data Recovery
we know who can fix it
And similar to the concept in the days when spy satellites intentionally crash landed their images on film cannisters in the ocean, there have been science projects in the digital camera and telemetry age which were designed to bring back space data from crashed balloons in SSDs. Sometimes bad things happened to the SSD afterwards. I had forgotten about but still love this SSD data survival story about Memtech - from 2005.

Re data loss - human error plays a big part in many stories of data loss (even in replicated servers) while human error is also one of the biggest vulnerabilities in data security.

In a reflective article looking back at my conversations with the data recovery market I note some of the things which surprised and impressed me at the time.

And having tracked the SSD data recovery market since before it began - I found a way to connect all the dots. the article


20 years ago - in stealth mode

by Zsolt Kerekes, editor - - September 12, 2018
I 've been perusing my emails of 20 years ago (September 1998) which was the month before I was due to launch my new site and I was curious to remind myself what kind of conversations I was having with people in the run up to doing that and - in effect - exiting stealth mode with an entirely web based publication which had no past print rooted brand strength.

I had already been publishing a server market guide for 6 years at that time (called the SPARC Product Directory) and my company had been operating a dotcom based business model funded by web advertising since 1996. But I wanted to make the new storage site look different and have its own identity.

Some of the new changes I planned to introduce in my new server-agnostic storage guide were more pictures (for example the branding images of the first few mice were already in hand) and the other "innovation" was to be the use of banner ads on the site - a design feature to which I had originally said no a few years before.
1 candle for each decade
when dealing with such a small cake
practicality dictates that one candle
for each decade is quite enough
In those 20 year old emails I was looking at this week a common thread was that none of my storage advertising customers had ever run banner ads to promote their enterprise products before and so therefore many of the conversations were about finding people to design them in time to launch the new site.

I have preserved some of these older ads for future historians (pre modern SSD era storage banner ads / pre millenium SPARC banner ads) because they still tell us a lot about the products and the excitement about the key messages about them from a perspective which you don't see in dry historical narratives. (I'll add some more of those early examples into an update of this blog so you can get an idea of how much things have changed since then.)

You can see below an example of one of the earliest storage banner ads designed specifically to run here.(The vendor was Dynamic Computer Products which soon after changed their business name to Data Storage Depot.
a RAID banner ad from september 1998
This rev 1.0 ad design above - "leaders in RAID, disk, tape and memory upgrades" - was created in September 1998 and like most ads underwent many design changes during the period that the ad programs ran. (Approximately 8 consecutive years with this customer - which was not unusual in my customer base during the 20 peak years of my web ad based business.)

If it wasn't for the brave companies who were designing ads for a new site which didn't exist yet and who weren't scared of mice then I wouldn't have had such a rewarding job for the next 20 years and my readers would've had to wait another 2 years to see the next wave of portals (that's what we called them back then) which covered the storage market as a disaggregated whole.'s initial storage-wide focus (from raw storage chips, and RAID systems, backup software to tape libraries) itself would later change when in about 2007 - on seeing the scale of my earlier predictions for the SSD market coming true - I quietly resolved to reduce my editorial coverage of things to do with the rotating storage market and instead refocus most of my energies on the rapidly changing SSD market. Which was just about as much as I thought I would be able to comfortably wrestle with given where the technology had started and where I thought it was going to go.

See also:- SPARC history, SSD market history, D2d (disk to disk backup) history


3d nand and new dimensions in SSD controller architecture

research exploits layer based differences

by Zsolt Kerekes, editor - - August 28, 2018
In the early years of nand flash memory adoption in the enterprise (for simplicity let's call this period the MLC (pre-TLC) / pre-adaptive R/W / pre-DWPD era) there wasn't the same kind of established delineation of application roles for new SSDs as there is now - SSD articlesbecause SSDs were still carving out new reasons to be used in design wins (almost one startup at a time) and it also happened quite often that when a new product was announced there would be significant gaps in the datasheets compared to what was needed to be known to determine how the product might behave (without having to invest large amounts of resources into benchmarking and evaluations).

To help my readers in this formative period I suggested several shortcuts which could help potential integrators group such new SSDs into sets determined by key design and architectural decisions in the new SSDs.

These enabled anyone who thought a lot about SSD controllers to decide for themselves - yes this new one is in this set and so some its characteristics are preordained - it's better at this, worse at at that - irrespective of whether there were any datasheets or benchmarks or whether we believed that such benchmarking had been correctly set up (which for a long time it wasn't). I know from the conversations I had with many systems designers that they found some of my "filtering" terms to be useful shortcuts - and most of the companies which were creating these new products found it useful to answer my questions about the internals of their designs and thinking.

But all such rules of thumb have a limited shelf life. And as I used to remind readers in my year end articles - it's just as important to discard old ideas which at one time were useful as it is to adopt new ones.

One of the simplest SSD design filters which I wrote about was something I called the difference between big and small SSD controller architecture (2011).

At the heart of this was the question - how many memory chips has the controller been optimized for? Because if it can work with a single digit set of chips then the controller can't employ as many clever strategies (to help reliability, performance and quality of performance) as another design which has been designed with a floor level of tens or hundreds of chips. It was a simple idea and it was a useful way to look at controller designs over a 10 year period.

But a paper I saw this month made me reconsider whether that division still works. And even to ask the question - are there any small architectue SSDs left at all?

The paper in question was - Improving 3D NAND Flash Memory Lifetime by Tolerating Early Retention Loss and Process Variation (pdf) by Yixin Luo and Saugata Ghose (Carnegie Mellon University), Yu Cai (SK Hynix), Erich F. Haratsch (Seagate Technology) and Onur Mutlu (ETH Zürich) - which was presented at the SIGMETRICS conference in June 2018.

This paper - among other things - suggests several new (not previously publicly written about) design approaches which can be adopted with tall (30 layers upwards) 3D nand flash - which can leverage characterization assessments which are made on a small sample of cells in a memory chip and leverage those with architectural support in an SSD controller to increase SSD reliability or performance so as to make enterprise use of such memories more attractive.

One of the ideas discussed in the above paper is the idea that the quality of cells varies in each layer. This in itself is not new. What is new however is that the authors show how the spread of reliability can be measured, modeled and harvested.

The authors say - "We are the first to provide detailed experimental characterization results of layer-to-layer process variation in real flash devices in open literature. Our results show that the raw bit error rate in the middle layer can be 6x the raw bit error rate in the top layer."

Among the many chip dependent design approaches in the paper here are 2 which I've singled out.
  • LaVAR - Layer Variation Aware Reading
  • LI-RAID - Layer-Interleaved RAID

Layer Variation Aware Reading (LaVAR) - "reduces process variation by fine-tuning the read reference voltage independently for each layer."

This idea - which properly occurs in the realm of adaptive R/W technology (rather than big controller architecture) suggests a simple model which can predict a best guess threshold voltage for P/E based on a top/bottom samples extracted after endurance conditioning a small number of blocks in the memory.

On its own - this concept would be enough to make the paper a must-read for controller designers.

My gut feel is this points the way to a middle course of run time controller design between 2 well known philosophies:-
  • the adaptive DSP ECC approach - which combines chip learned characterization with heavy weight run time processing power in the target controller and
  • the machine learning / lifetime based characterization models proposed by NVMdurance in 2013 - which enables lightweight run time processing - based on a model which extrapolates the best figures for a population of all memory chips - but is learned from a factory based characterization (rather than learned from the local chips attached to the controller).

Layer-Interleaved RedundantArray of Independent Disks (LI-RAID) - "improves reliability by changing how pages are grouped under the RAID error recovery technique. LI-RAID uses information about layer-to-layer process variation to reduce the likelihood that the RAID recovery of a group could fail significantly earlier during the flash lifetime than the recovery of other groups."

This - to me - starts to look like another "big controller" architecture idea - but the authors say it can be used in an SSD with just a couple of chips. They also extend the concept to pairing the best predicted blocks in one memory chip with the worst predicted blocks in another memory chip in the same SSD.

You can read about earlier uses of RAID thinking in SSD controller designs (including variable size planes) in my RAID systems page.

But it's clear that the interpretation of different layers in a 30 to 100 layer or so 3D memory chip starts to look a lot like big controller architecture.

Previously it was the number of different identifiable conceptual toys in the box which set the limits to system level design tricks. Now it's layers in the same chip too.

some earlier home page blogs

re RATIOs in SSD architecture

40 years of thinking about non volatile memory endurance

miscellaneous consequences of the 2017 memory shortages

are we ready for infinitely faster RAM? (and what would it be worth)

introducing Memory Defined Software - yes seriously - these words are in the right order

Hmm... it looks like you're seriously interested in SSDs. So please bookmark this page and come back again soon.

storage search banner
SSD ad - click for more info

SMART's Gen-Z Module
Spin Memory licenses IP to Arm
the security blanket of encrypted SSDs?
Everspin secures more fab capacity for MRAM
Princeton's in-memory accelerator uses switched
caps to take neural matrix MACs out of the digital box

see news page
If you could go back in time and take with you a load of memory chips and SSDs from today (along with compatible adapters so they could plug and play) how would that change the world?
What if you could bring back SSDs from the future?
Controllernomics - is that even a real word? Memoryfication? PIM, NVMeoF, pSLC etc
dipping into the waters of SSD jargon
Since the early 1970s there have been 3 revolutionary disruptive influences in the electronics and computing markets.
  • the microprocessor
  • the commercialization of the internet
  • the advancement of computer architecture
    enabled by the modern era of SSDs
comparing the SSD market to earlier tech disruptions
Diskful Writes Per Day began as a shortcut to describe the endurance of SSDs in enterprise SSDs but within a couple of years it became adopted by other markets too - for industrial, military and even (surprisingly) consumer drives. It has been a useful metric but has its limitations too.
what's the state of DWPD?
"...the SSD market has been the main incubator for disruptive memoryfication trends but now - as we approach the series finale of the Top SSD Companies - I think a new list tracker is needed."
the Top SSD Companies in Q2 2018
This is a genuine problem for the SCM
(storage class memory) industry.
How to describe performance.
is it realistic to talk about memory IOPS?
The semiconductor memory business has toggled between under supply and over supply since the 1970s.
boom bust cycles in the memory market - an SSD view
It was the best of times.
It was the worst of times.
2017 was a year like no other in 40 years of SSD history.
which way next for SSD?

Some of the winners and losers from the memory shortages in 2017 were easy to spot. But there have been new opportunities created too.
consequences of the 2017 memory shortages

Despite many revolutionary changes in memory systems design and SSD adoption in the past decade we are still not at the stage where it's possible to predict and plot the next decade as merely an incremental set of refinements of what we've got now.
Are we there yet? - 40 years of thinking about SSDs

Say farewell to friction-free borderless memory markets.
can memory chips be made in the wrong country?

Data recovery from DRAM?
I thought everyone knew that

the dividing line between storage and memory is more fluid than ever before
where are we heading with memory intensive systems?

Enterprise DRAM has the same latency now (or worse) than in 2000. The CPU-DRAM-HDD oligopoly optimized DRAM for a different set of assumptions than we have today in the post modern SSD era.
latency loving reasons for fading out DRAM

This may be a stupid question but... have you thought of supporting a RAMdisk emulation in your new "flash tiered as RAM" solution?
what characteristics could we learn?

How do we know anything?

And how confident can we be when using that knowledge as the basis to make important decisions?

I'm not talking here "cogito ergo sum" but the rather more down to earth matter of - how well can anyone today understand the SSD market? - and give you a reliable answer to a simple question like - what's the best way of getting to SSD street from wherever your starting point happens to be right now.
Can you tell me the best way to get to SSD Street?


The enterprise SSD story...

why's the plot so complicated?

and was there ever a missed opportunity in the past to simplify it?
the elusive golden age of enterprise SSDs

To be? or Not to be?
hold up capacitors in 2.5" MIL SSDs
0 to 3 seconds - aspects of extreme SSD design

Why do SSD revenue forecasts by enterprise vendors so often fail to anticipate crashes in demand from their existing customers?
meet Ken and the enterprise SSD software event horizon

I said to Rob Peglar - "The ratio of processor cores to memory channels and local memory capacity is a solid pivot from which to leverage your forthcoming architecture blogs. I love ratios as they have always provided a simple way to communicate with readers the design choices in products which tell a lot to other experts in that field."
re RATIOs in SSD architecture

Compared to EMC...

ours is better
can you take these AFA startups seriously?

Now we're seeing new trends in pricing flash arrays which don't even pretend that you can analyze and predict the benefits using technical models.
Exiting the Astrological Age of Enterprise SSD Pricing

Reliability is an important factor in many applications which use SSDs. But can you trust an SSD brand just because it claims to be reliable in its ads?
the cultivation and nurturing of "reliability"
in a 2.5" embedded SSD brand

A couple of years ago - if you were a big company wanting to get into the SSD market by an acquisition or strategic investment then a budget somewhere between $500 million and $1 billion would have seemed like plenty.
VCs in SSDs and storage

Adaptive dynamic refresh to improve ECC and power consumption, tiered memory latencies and some other ideas.
Are you ready to rethink RAM?

90% of the enterprise SSD companies which you know have no good reasons to survive.
market consolidation - why? how? when?

With hundreds of patents already pending in this topic there's a high probability that the SSD vendor won't give you the details. It's enough to get the general idea.
Adaptive flash R/W and DSP ECC IP in SSDs

SSD Market - Easy Entry Route #1 - Buy a Company which Already Makes SSDs. (And here's a list of who bought whom.)
3 Easy Ways to Enter the SSD Market

"You'd think... someone should know all the answers by now. "
what do enterprise SSD users want?

We can't afford NOT to be in the SSD market...
Hostage to the fortunes of SSD

Why buy SSDs?
6 user value propositions for buying SSDs

"Play it again Sam - as time goes by..."
the Problem with Write IOPS - in flash SSDs

Why can't SSD's true believers agree upon a single coherent vision for the future of solid state storage? (They never did.)
the SSD Heresies.

The predictability and calm, careful approach to new technology adoption in industrial SSDs was for a long time regarded as a virtue compared to other brash markets.
say farewell to reassuringly boring industrial SSDs

If you spend a lot of your time analyzing the performance characteristics and limitations of flash SSDs - this article will help you to easily predict the characteristics of any new SSDs you encounter - by leveraging the knowledge you already have.
flash SSD performance characteristics and limitations

The memory chip count ceiling around which the SSD controller IP is optimized - predetermines the efficiency of achieving system-wide goals like cost, performance and reliability.
size matters in SSD controller architecture

A popular fad in selling flash SSDs is life assurance and health care claims as in - my flash SSD controller care scheme is 100x better (than all the rest).
razzle dazzling flash SSD cell care

These are the "Editor Proven" cheerleaders and editorial meetings fixers of the storage and SSD industry.
who's who in SSD and storage PR?