PCIe SSDs for use in enterprise server acceleration have been shipping
in the market since
one of the
most popular SSD
subjects pursued by our readers and has been (and has been since
2009 - when we
first told you that searches for PCIe SSDs on
StorageSearch.com - had overtaken
searches for 2.5"
SSDs on this site for the first time in
With over 100 million enterprise PCIe ports already shipped in
the market (upto January 2014) and with waiting-to-be-exploited fabric
capabilities which chipmaker PLX
(by which they mean PCIe as a fabric outside the box but still within the
cabinet) the fast changing and converging PCIe SSD / server market is
well positioned to expand into new applications.
Over 40 companies
already ship enterprise accelerator PCIe SSDs (see list below).
That will rise to over 100 companies as the availability of more
SSD controller chips,
other SSD related chip sets and
IP and SSD software
for this market will make it even easier than it already is for newcomers to
enter the PCIe SSDs market.
PCIe SSDs come in several shapes and
sizes. The most familiar form factor is cards, modules and racks. But a new
form factor - for
2.5" PCIe SSDs
which emerged in
2012 are opening up new applications - such as the displacement of fast
the 2nd half of 2013 - we also saw the start of another type of deployment for
the PCIe interface in the M.2 form factor which is aimed at the
consumer SSD market
notebooks. These consumer PCIe products have throughputs similar to the
enterprise products of 5-6 years earlier - but aren't rated for heavy
Nevertheless I wouldn't be surprised to see them appear as
in some future arrays in read-intensive design slots.
competitive alternative to PCIe SSDs - at the low latency end of the
applications spectrum inside (rather than
outside) the server box -
which started shipping in volume in 2014 - is a new class of low latency flash
SSDs which plug into DIMM sockets which were originally designed for
read more about these products (which go by various names such as TeraDIMMs,
ULLtraDIMM SSDs, eXFlash DIMMs etc) in the
|don't all PCIe SSDs
look pretty much the same?|
|When you look at the
photos and headline specs for high speed PCIe SSDs - it's easy to come away with
the impression that they all look the same and have about the same performance.|
all - how different can they be?
But don't let the experience of the
SAS markets - in which
enterprise SSD vendors cluster close together in performance rankings - give
you the wrong idea about PCIe SSDs.
In this market the performance
limits and capabilities of the SSD aren't set by fossilized
hard disk interface
and package limitations. They're limited only by the imagination of the
designers - tempered by the
educated guesses of
marketers who are trying to predict the optimum (most salable) features for
an ideal server side enterprise SSD.
|how fast can your
SSD run backwards?|
|SSDs are complex devices and there's a
lot of mysterious behavior which isn't fully revealed by benchmarks, datasheets
and whitepapers. |
Underlying all the important aspects of SSD behavior
which arise from the intrinsic technologies and architecture inside the SSD.
|Today's commodity MLC flash
has raw wear-out in the 2,000 to 3,000 write cycle range. And the future
direction is downwards (towards worse).|
|SSD endurance - the
|the Problem with
Write IOPS in flash SSDs |
|Random "write IOPS"
in many of the fastest flash SSDs are now similar to "read IOPS"
- implying a performance symmetry which was once believed to be impossible.|
why are flash SSD IOPS such a poor predictor of application performance?
why are users still buying
RAM SSDs which cost an
order of magnitude more than SLC? (let alone
MLC) - even
when the IOPS specs look superficially similar?
tells you why the specs got faster - but the applications didn't.
||And why competing SSDs with
apparently identical benchmark results can perform completely differently.
|This is a (partial list) from
past SSD news and
Mach Xtreme Technology,
Renice Technology ,
, Texas Memory
|many years ago -
|BiTMICRO & CENATEK collaborate on PCI SSDs|
2002 - BiTMICRO.
announced today, a technology and marketing partnership to investigate
developing a hybrid solid state disk storage solution that brings together the
best in flashdisk storage and PCI bus-attached SSD technology.
Prices are likely to
range between $1,000 to $2,000 per gigabyte.
Editor's later comments:- the fast PCI SSDs which later
emerged from CENATEK - can be seen as immediate ancestors of the modern PCIe
But the concept of using fast bus based SSDs as storage
accelerators wasn't a new idea. It went back 3 to 4 decades.
earlier market experiments with solid state storage were always short lived -
because the expensive SSD storage in each product generation was always
competing with fast changing improvements in CPU clock speeds, bus memory
throughput or faster external magnetic storage media.
The changes in
the modern era of
SSDs - which started about 2003 - was that due to those other computer
technologies stagnating and not getting any faster - the only competitor which
killed an SSD from about that time - was another SSD.
By that time -
the new computer bus was known to be PCI express. But it was the failure of the
alternatives to solid state storage to get faster - which made the big
difference to the business viability of SSDs - rather than any inate
characteristic of PCIe SSDs.
|the fastest SSDs|
SSD endurance -
changed in SSD year 2013?
all enterprise data
will touch an SSD
how fast can your SSD
SSD symmetries in
design and performance
don't all PCIe SSDs
look pretty much the same?
SSDs - the Survive and Thrive Guide
what's in an SSDserver
rank number? - for PCIe - add 2
news below / SAS SSD
news / other SSD news|
|what's the market for
Plextor's PCIe SSD?|
Editor:- April 7, 2014 - I asked Plextor's virtual
marketing representative in the US - Andrew Erickson at
Alaniz Marketing to tell me more
about Plextor's thinking about routes to market for their entry level (Gen2)
PCIe SSD market
offering - the
said - "The M6e is marketed directly to consumers as an end-user upgrade
and mostly via newegg and major e-tailers."
Andrew went on to say - "Plextor is definitely moving into the
enterprise space and we're expecting to see a couple of read intensive and
multi-use ssd products later this year. It sounds like some of the enterprise
firmware advances may already be evident in the M6e - though it's not being
marketed in that way. I have seen some Plextor drives sold in high end gaming
rigs, but I'm not aware of current plans to sell OEM at this time."
Samsung's new 2.5" NVMe PCIe SSD
March 25, 2014 - Although Samsung's own
meat navigation inspired
SSD selection page doesn't list this product yet (at the time of writing
this) Samsung is engaged in the
2.5" PCIe SSD
market - and is shipping a 1.6TB NVMe PCIe SSD rated at
7 DWPD for 5
years to Dell for use
in its PowerEdge
PCIe Switching - new article in EnterpriseTech.com
March 13, 2014 - A new article in EnterpriseTech.com
Switching Takes on Ethernet, InfiniBand - reviews the antecedents and
current state of the PCIe fabric market.
This should be of interest
to anyone thinking about the emerging architectural influences which may
impact their plans within the
PCIe SSD market.
of the many vendors discussed in the article - PLX - says it's "not
targeting warehouse-scale datacenters... but is rather thinking on a smaller
scale, from hundreds to thousands of nodes." ...read
a new SSDserver nomenclature?
Editor:- March 5, 2014
- In a new home page blog today - StorageSearch.com
published proposals for a new shorthand for SSD enhanced enterprise
servers in the context of complex architectural dialogs. ...read the article
(You won't need this if all your projects look the same, or if your plans only
include small numbers of SSDservers.)
OCZ launches Z-Drive 4500 - 19nm enterprise PCIe SSD
March 4, 2014 - OCZ
is still using LSI's
SandForce SSD controllers
SF-2582 enterprise SATA (pdf)) in its newest PCIe SSD - the
Z-Drive 4500 Series
today - which has upto 3.2TB of usable
19nm flash, R/W bandwidth
of 2.9GB/s and 2.2 GB/s respectively, and 252K / 76 K R/W
in a FHHL form factor and is integrated with OCZ's new WXL caching software.
4500 briefing notes (pdf)
Editor's comments:- As I
reported in an interview
last November - OCZ's VXL bundles have been very successful in small to
medium scale enterprise deployments. The evolution of this product line -
supporting as it does another new generation of (lower cost) memory - will
further extend its reach.
A3CUBE unveils PCIe memory fabric for
PCIe SSD architectures
Editor:- February 25, 2014 -
PCIe SSDs can now
access a true PCIe connected shared memory fabric designed by A3CUBE - which exited stealth today
of their remote shared broadcast memory network -
RONNIEE Express -
which provides 700nS (nanoseconds) raw latency (4 byte message) and which
enables message throughput - via standard PCIe - which is 8x better
Editor's comments:- I spoke to the
recently - who say they intend to make this an affordable mainstream
The idea of using PCIe as a fabric to share data at low
latency and with fast throughput across a set of closely located servers
isn't a new one.
The world's leading PCIe chipmaker
PLX started educating
designers and systems architects about these possibilities
few years ago - as a way to elegantly answer a new set of scalability
problems caused by the increasing adoption of PCIe SSDs. These questions
- how do you make this expensive resource available to more servers?
the least year or so - we've seen most of the leading vendors in the enterprise
PCIe SSD market leverage some of the new features in PCIe chips - to
implement high availability SSDs with low latency.
- how do you enable a simple to implement failover mechanism - so that data
remains accessible in the event of either a server or SSD fault?
But although there
are many ways of doing this - the details are different for each vendor.
- until now - if you wanted to share data at PCIe-like latency across a bunch
of PCIe SSDs from different companies - located in different boxes - the
simplest way to do that was to bridge across ethernet or infiniband. - And even
though it has been technically possible with standard software packages - the
integration, education and support issues - compared to legacy SAN or NAS
techniques would be extremely daunting.
That's where A3CUBE comes into
the picture. Their concept is to provide a box which enables any supported PCIe
device to connect to any other - at low latency and with high throughput -
in an architecture which scales to many thousands of nodes.
heart of this is a shared broadcast memory window - of 128Mbytes - which can be
viewed simultaneously by any of the attached ports.
ever used shared remote memory in a supercomputer style of system design at
any time in the past 20 years or so - you'll know that the critical thing is how
the latency grows as you add more ports. So that was one of the questions I
Here's what I was told - "The latency is related to the
dimension of the packet for example: In a real application using a range of
64-256 bytes of messages the 3D torus latency doubled after 1,000 nodes.
With larger packets, the number of nodes to double the latency becomes grater.
But the real point is that the latency of a simple p2p in a standard 10GE is
reached after 29,000 nodes.
"A more clear example of the scalability of the system is this.
Imagine that an application experiences a max latency of 4 us with 64 nodes, now
we want to scale to 1,000 nodes the max latency that the same application
experience will became 4.9 us. 0.9 us of extra latency for 936 more nodes."
Editor again:- Those are very impressive examples - and demonstrates that the
"scalability" is inherent in the original product design.
didn't want to say publicly what the costs of the nodes and the box are at this
stage. But they answered the question a different way.
Their aim is to
price the architecture so that it works out cheaper to run than the legacy
(pre-PCIe SSD era) alternatives - and they're hoping that server oems and fast
SSD oems will find A3CUBE's way of doing this PCIe fabric scalability stuff -
is the ideal way they want to go.
There's a lot more we have to learn
- and a lot of testing to be done and software to be written - but for users
whose nightmare questions have been - how do I easily scale up to a 10,000
PCIe SSD resource - and when I've got it - how can I simplify changing
suppliers? - there's a new safety net being woven. Here are the
PLX is ready with 1st Gen3 compliant PCIe switches
February 4, 2014 - PLX
announced it is
the 1st PCIe switch vendor to have achieved Gen3 compliance having passed the
compliance testing procedures of PCI-SIG.
Editor's comments:- the new standard doubles the maximum
data bandwidth of PCIe SSDs to 1GB/s per lane in each direction - which enable
32GB/s total throughput for a x16 link.
SSD interface chips,
Express 3.0 Integrators List
ESG reports on clustering Virident's PCIe SSDs
January 23, 2014 - ESG
today published a
report for Virident
/ HGST's FlashMAX
II (PCIe SSDs)
which validated the ability of this product family and its
(vShare ) to be configured for useful operation in an Oracle RAC environment
availability configurations which were clustered via
ESG said performance was good they also commented on some current
limitations of the product suite for this type of application. In particular:-
- the lack of a graphical interface for setup and performance mintoring,, and
- the lack of support for other supported fabrics such as 10GbE (mentioned
in the report as a future option), and PCIe fabric (which was not mentioned at
all in this report).
This is what it takes to be #2 in PCIe SSDs
January 22, 2014 - LSI
said today in its
financial report it has shipped over 100,000
PCIe SSDs since it
entered this market in April 2012.
Editor's comments:- LSI
shipped 60,000 units in the 8 months from May to December 2013 (a figure
calculated by subtracting the numbers contained in an
Despite those impressive numbers - LSI itself
estimates that it is still the #2 company in this market. Which gives you an
idea of how large this market has grown.
IBM launches first memory channel SSD based servers
January 16, 2014 - IBM
today disclosed preliminary test results comparing the latency of
SSDs to PCIe SSDs - in the
press release of its new X6 architecture for X86 servers.
- "Our evaluators are seeing 5-10 microseconds write latency for eXFlash
DIMMs in preliminary testing vs. 15-19 microseconds latency for PCIe-based flash
storage from Fusion IO,
Virident, and 65
microseconds latency for Intel
S3500 and S3700 SSDs."
IBM also announced enhancements and sales
figures for the rackmount
SSD product line it acquired from
Texas Memory Systems a
year ago. See SSD news for
more about the latter.
reasons to expect more PCIe SSDs in 2014 PC Market
December 16, 2013 - A new
in DRAMeXchange discusses the issue of
SATA 3 SSDs being
replaced by PCIe SSDs
in the consumer SSD
market in future designs of PCs. ...read
how to avoid hot pluggable PCIe SSD failures
December 3, 2013 - What happens if you test
PCIe SSDs for their
sensitivity to data
corruption or even failure
- in the event of
You'd think that with more hot pluggable products coming
into the market -especially in the
2.5" form factor
- that the experimental outcomes would be known by the designers and problems
debugged so that users wouldn't have to worry.
In August 2013 Quarch Technology
launched some special
test equipemnt to inject power related faults into PCIe SSDs - and the
company today announced
it has extended this range to automate power line error testing of PCIe SFF
Technical Director at Quarch Technology told me today that "Almost every
combination of test kit we have tried in Quarch (a number of friendly customers
lent us kit and eval drives to get the new module up and running) has failed in
some way. Sometimes failing to come back up again nicely, sometimes with a full
BSOD which will almost
certainly have risked data loss."
estimating the size of the server-side SSD market etc...
October 8, 2013 - Before you make that next presentation about what's happening
in the business world of enterprise flash, or before you commit to any future
datelines for hard drives being sold into the enterprise - you'd be well
meet Ken and the
enterprise SSD software event horizon - the (long anticipated) new home
page blog on StorageSearch.com.
new route to market for FIO's ioScale
September 26, 2013 - IBM
- which has been offering Fusion-io's ioDrive
(PCIe SSD) technology
in its product line since
December 2009 has
first server oem to remarket the
ioScale - a product
described as having been optimized (price and feature set-wise) for huge
end users in the SSD
dark matter segment at the time of its launch in
Demartek blog re NVMe
Editor:- September 19, 2013 -
PCIe SSD market was
threatened with standards
which might tame it several years ago. The state of play is assessed in a new
IDF2013 and NVMe written by Dennis Martin, President
LinkedIn uses Virident SSDs
Editor:- August 28, 2013
- Virident Systems
that LinkedIn is a customer of its
Skyera offers PCIe attach to petabyte class SSD
August 13, 2013 - Skyera
that. among other things, it will introduce
PCIe connectivity (to
the existing FC and
iSCSI) as well as
replication in the next version of its
rackmount SSDs -
the skyEagle - which will ship in the first half of 2014 - offering 500TB
uncompressed (2.5TB deduped and compressed) in a 1U form factor at a record
breaking list price
expected to be under $2,000 per uncompressed terabyte.
SMART starts sampling ULLtraDIMM SSDs
8, 2013 - SMART
Storage Systems today
it has begun sampling the first memory channel SSDs compatible with the
interface and reference architecture created by Diablo Technologies.
first generation enterprise ULLtraDIMM SSD (ULL = ultra-low latency) can be
deployed via any existing DIMM slot and provides 200GB or 400GB of enterprise
class flash SSD memory with upto 1GB/s and 760MB/s of sustained read/write
performance, with 5 microseconds write latency. Throughput, IOPS and memory
capacity scale with the number of ULLtraDIMM deployed in each server.
Samsung enters the 2.5" PCIe SSD market
July 18, 2013 - Samsung
today announced its entry into the
2.5" PCIe SSD
market. Its new NVMe SSD has upto 1.6TB capacity, read throughput upto
3GB/s, and up to 740K
PCIe topologies for enterprise SSDs
17, 2013 - PLX Technology
recently published a white paper -
and PCI Express - which gives an overview of past, current and future PCIe
SSD connection topologies along with a list of detailed reference articles.
with the clear text and authoritative viewpoint (PLX is the leading supplier of
PCIe chips to the SSD industry) the article includes a complete set of
attractive pictures too - which make it easier to visualize the many different
interconnection methods being discussed. Below is an example from a section in
the paper - called - Taking PCIe Out of the Box.
In recent years we've seen the start of a growing
diversity in both
the type and functionality of
PCIe SSDs. PLX's new
article provides a good introduction to what can be done with PCIe in an SSD
context - and may make you rethink your ideas about the roles of this interface
interface chips and IP,
7 silos for enterprise
Samsung enters PCIe SSD market
Editor:- June 17,
2013 - Samsung
has entered the PCIe SSD
market with an M.2 form factor model (80mm x 22mm) aimed at
Samsung's XP941 - which weighs less than 6g - has a sequential read
performance of 1,400MB/s, and capacity up to 512GB.
market began the year before PCIe SSDs started being used in the
But in the first 5 years of its history (2006-2010) the
notebook SSD market was a disappointment to SSD evangelists like me - because
integration with PCs was so bad. And for years on these pages I ranted that
notebooks using SSDs would never be able to reach their true potential as long
as they were still wasting their inherently light CPU resources and latency
advantages by talking to the CPU via old fashioned
hard disk interfaces
exciting thing about today's announcement by Samsung is that consumer grade
PCIe SSDs for notebooks will enable a dramatically different user experience
which will help to create new markets.
Will there be a crossover into
the enterprise market?
It's inevitable that some people will ask -
what would an array of consumer priced PCIe SSDs look like in a box? And no
doubt you will probably see such products coming onto the market. And that
might lead to a temporary state of user confusion about expectations for PCIe
But setting aside for the moment the obvious considerations at
the single drive level of differences in
characteristics - I think the key differentiators of enterprise PCIe SSDs
compared to consumer
PCIe SSDs are the different degree of
(higher for the enterprise),
management and support for fault tolerance.
Violin's new blog on PCIe vs FC SAN SSDs
June 11, 2013 - How much confidence do you have in the
of the SSD system which you're deploying? - And how different are the
reliability costs when you scale
PCIe SSDs compared to
are some of the issues discussed in a new blog by Violin -
Memory: too Array or to Card - written by the company's CTO of Software -
Goldick - who warns that when you're estimating the latency
advantages between different ways of connecting SSDs - "Always be
cognizant that you may just be moving the
to the software."
Micron turns up the heat for adoption of 2.5" PCIe SSDs
May 3, 2013 - Micron
it's sampling a new model in the
hot swappable 2.5"
PCIe SSDs market - the
has upto 1.4TB MLC capacity and can deliver 750K R IOPS.
QLogic enters the enterprise SSD market - with SAN IOPS caching
Editor:- March 22, 2013 - QLogic yesterday
entered the enterprise
SSD market (in the PCI
SSD and SSD ASAPs
segments) with the
its first product - the
10000 Series adapter (pdf) - which provides transparent sharable and
clusterable caching for FC SANs.
The 2 card set (upto 400GB flash,
and 2x 8Gbps FC ports) can deliver upto 310,000 initiator IOPS and
supports upto 2,048 concurrent logins.
QLogic says - FabricCache uses
just a single standard adapter driver per OS, the same QLogic field-proven
adapter driver stack that has shipped with more than 13 million FC ports. The
FabricCache adapter appears logically to the server as a single QLogic HBA which
integrates seamlessly into current enterprise server and infrastructure
Editor's comments:- from the business and
marketing perspective QLogic's new Mt. Rainier branded SSD is a tardy,
pragmatic and cunning response to the threats and challenges posed by SSDs
to traditional storage ecosystems vendors.
Tardy - because
the first SSD ASAP appliances - which used SSDs to automatically and
transparently accelerate access to
SAN storage first shipped
in 2009. And
the first enterprise PCIe SSDs started shipping in 2007.
- for a bunch of reasons
- Pragmatic - because QLogic's new products provide a credible way for the
company to participate and get customer experience in the crowded high
value PCIe SSD market - by recycling IP from (what would otherwise soon be
downgraded to) a commodity IP base (FC SAN physical adapters).
my 2011 article - don't
all PCIe SSDs look pretty much the same? - SSD ASAPs (like QLogic's
FabricCache ) were discussed as one of the many options for market
- because the implied message to users here is:- "if you want to fool
around with SSD auto-accelerating your SAN storage - you can do it without
haveing to learn about new software. - All the software you need to know about
is already running your interface HBAs."
- Pragmatic - for another reason too - because with 50 or more different
flavors of auto-caching/tiering software schemes already in the market - QLogic
has neatly side-stepped the issue of participating as yet another new
SSD software company
which user have got to learn about - and instead has cleverly positioned its
product as needing no new software. (The FabricCache adapters learn everything
they need to know from being acticated by standard FC HBA drivers.)
This is kind of sneaky -
because in reality - if users are investing in this product - they will soon
start to care about the internals of the software - and to ponder on the
ability of QLogic to continue delivering good
symmetry across upcoming new generations of back end SAN storage systems as
these SAN racks themselves change their internal make-up from hard drives to
Another consideration is that - accelerating data I/O between a
traditional server SAN stack and storage on the SAN - may give better results
than without any flash - but may not be as good an ROI as the competing
alternative of accelerating apps performance using similar flash capacity
but with an interface agnostic bunch of algorithms.
QLogic's new SSDs provide a "low perceived risk" way for users -
who don't want to plunge deeply into the mystical and changeable details of
SSD acceleration - to experiment and fool around with the benefits of SSD
Before I get any emails from investors asking - is
this good for QLogic? or - is it bad for
Virident)? Here are
Companies in the server SAN infrastructure market have no
future without an SSD core. So having a plausible SSD product - even at this
late stage of the enterprise SSD market development game- upgrades QLogic from
a future as a mere commodity interface chip supplier to a plausible player.
I doubt if any PCIe SSD makers feel in any way threatened by QLogic's new
See also:- QLogic's informative white paper -
Mt. Rainier Integrates SSDs with SAN Connectivity (pdf)
9 million IOPS in a single PCIe SSD
5, 2013 - Fusion-io
it has achieved 9.6 million
byte) from a single 365GB
ioDrive2 (PCIe SSD).
performance is made possible using APIs in
SDK (such as Auto-Commit Memory) which integrate flash into host systems,
allowing data to bypass normal bottlenecks in the OS.
FIO says its
APIs have been embraced by dozens of industry-leading
software companies to
enhance their applications.
|archived versions of this PCIe SSDs news page
|the SSD Buyers Guide|
where are we now with SSD software?
SSDs for newbies - what are they etc
|the 3 fastest flash
PCIe SSDs - list / lists|
|Are you tied up in
knots trying to shortlist flash SSD accelerators ranked according to
published comparative benchmarks?|
You know the sort of thing I mean -
where a magazine compares 10 SSDs or a blogger compares 2 SSDs against each
other. It would be nice to have a shortlist so that you don't have to waste too
much of your own valuable time testing unsuitable candidates wouldn't it?
StorageSearch's long running
fastest SSDs directory
typically indicates 1 main product in each form factor category but those
examples may not be compatible with your own ecosystem.
If so a
new article -
the 3 fastest PCIe
SSDs list (or is it really lists?) may help you cut that Gordian
knot. Hmm... you may be thinking that StorageSearch's editor never gives easy
answers to SSD questions if more complicated ones are available.
||But in this case you'd be
wrong. (I didn't say you'd like the answers, though.) ...read the article|
|How are fault tolerant
PCIe SSD designs supported in chips?|
enterprise SSD designs - this video by PLX includes an
introductory tutorial into PCIe and its performance and architectural
capabilities for SSDs including automatic failover and multi-host capabilities.|
|PLX's switch chips also supports failover if
the fault occurs in the PCIe switch fabric chips themselves.
extract - "...And in case one of the hosts fails
and you want to connect the SSDs - or the devices connected to that host - to
another host - that can be done automatically as well - and the surviving host
can attach the devices that were attached to the failing host to itself and
control it so that the system doesn't go down and the data stored in these
devices doesn't get isolated from the main system."
|How Big is the Market for
|In 2010 I wrote here that I confidently
expect that PCIe SSDs will become a multi-billion dollar a year market.|
now the standard SSD
Since 2010 most of
the top 10 SSD companies
also sold PCIe SSDs.
For more about PCIe SSDs fit into the enterprise SSD landscape see -
introduction to SSD
|"This is a tsunami warning
event for SSD vendors addressing the enterprise server acceleration market."|
|...editor's comments (September 24, 2009 ) when
I alerted readers and vendors to the fact that search volume for PCIe SSDs
had surpassed that for 2.5" SSDs for the first time. |
type of search spike had been a reliable advance
predictor for new
interfaces - such as SATA
and iSCSI - in earlier
phases of storage
history - and search volume has also been a good predictor for
successful SSD companies
SSDs Technical Pros and Cons|
|The great attraction of PCIe for SSD
oems is that it can support a wide range of performance options with throughput
upto 16GB/s, and much lower attachment costs than the
older busses like PCI and cPCI also provide performance which is adequate for
Bus connected SSDs have been around since the
of the SSD market.
The advantage of this approach is high
throughput and low latency compared to SSDs connected via traditional hard disk
style interfaces like
there are disadvantages too which include:-
1 - Bus style
interfaces reduce the available market for the SSD oem. Because older servers
may not have the interface, or perhaps the interface (for example Sun's SBus) is
proprietary and is only available in a small range of models.
2 - Bus
interfaces tend to have shorter permissable cable lengths - which restrict how
such SSDs can be connected.
3 - Bus interfaces usually don't include
intrinsic end to end error detection and correction. If the physical arrangement
of the SSD pushes the speed and cable lengths too far - then errors can arise in
the bus connect - which have to be dealt with in the associated driver.
May 13, 2009 - Dolphin's
CTO, Venkat Krishnan emailed this article correction.
StorExpress addresses concerns of PCIe direct attached SSDs raised in (2) above.
It includes support for different types of PCIe interfaces (ExpressModule, AMC,
etc.). Multiple PCIe SSD cards can be used without requiring multiple PCIe slots
in the server. The storage can be collocated at distances of up to 300m from the
server and can also be potentially shared by more than one server."