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20 years - leading the way to the new storage frontier .....
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what's RAM really? ..
SSD news since 1998
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military storage directory and news
military SSDs ..
M.2 SSDs ..
image shows megabyte waving the winners trophy - there are over 200 SSD oems - which ones matter? - click to read article
top SSD companies ..
pcie  SSDs - click to read article
PCIe SSDs ..

SSD history
fastest SSDs
hybrid DIMMs
rackmount SSDs
storage reliability
ratios in SSD architecture
11 Key Symmetries in SSD design
InfiniBand history - from IB dawn to dusk
adaptive R/W and DSP ECC in flash SSDs
decloaking hidden segments in enterprise flash
AccelStor NeoSapphire  all-flash array
1U enterprise flash arrays
InfiniBand or 10GbE iSCSI or 16Gbps FC
NeoSapphire series - from AccelStor
ArmourDrive, Clipper, Lightning, tachIOn...
Metaphors in SSD brands
Is big always better?
the ups and downs of holdup caps in 2.5" MIL SSDs

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

1973 - 2017 - the SSD story

2013 - SSD market changes
2014 - SSD market changes
2015 - SSD market changes
2016 - SSD market changes
2017 - 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.
news:- Violin acquires X-IO Storage

what's next on

by Zsolt Kerekes, editor - - October 9, 2018
editor at workHere are 3 new SSD articles to look forward to in October. (When you see the links - that means they're ready.)
  • The problem with C - (the Michelson Morley kind - not the programming language). And a subtitle for this is:- introducing the data butler. (In this article you'll see what has guided my thinking about bottlenecks for the past 30 years, why processors, memory and communications are the way they are and why processing in memory is just a new word for old ideas.)
  • new edition of the SSD Bookmarks - in this one I turn the format on myself. (It was much easier when I was aiming the questions at others.)
  • the top SSD companies - wrap up edition. (So much has changed in the SSD market sine that series started. Over 40 quarterly editions. What can we learn from it all?)
OK - and if you thought the title was referring to something else. (Because readers have been asking me.) Well I've still got a lot to do before I'm done. So stick around and check in weekly to see the new articles in the list above as they make their appearances.

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
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?
what's the value of infinitely faster RAM?
Controllernomics - is that even a real word? Memoryfication? PIM, NVMeoF, pSLC etc
dipping into the waters of SSD jargon
SSD ad - click for more info
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.
miscellaneous 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?