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by Zsolt Kerekes,
editor - September
29, 2010 |
You may think that the so
called "enterprise
SSD" market is already complicated enough - but there are many more
product implementation choices and technologies which will make the spectrum of
enterprise SSDs clamoring for your attention wider than it is now and harder to
focus on and latch onto quickly.
I'm not just talking about the
proliferation of memory types. There are
5 different
memory types currently being marketed in "enterprise SSDs" and
more on the way. |
And I'm not talking about the
different architectures (open versus proprietary)
which already occur in vanilla
rackmount SSDs.
And
I'm not just talking about whether users are better off with SSDs which can
tune themselves (using one of the many different types of algorithms embedded in
SSD ASAPs) versus the
old fashioned way of getting
SSD tuning done
manually.
And I'm not just talking about application specific SSDs -
which already exist in some market segments - and will be a much bigger part
of the future SSD
market.
What I'm proposing is a simplistic way to view all these
products (and those still to come) through a technology-agnostic lens (mental
trick) which quickly helps you decide whether you should invest more time
reading about new SSD products which fall under the "enterprise SSD"
umbrella.
In my view all enterprise SSDs can be thought of as
belonging in one of 2 categories
- Legacy - the SSDs are going into an architecture originally
purchased by the user with just
HDDs in mind.
- New Dynasty - the SSDs are going into a user base or factory fitted
box always intended to have SSDs from the initial purchase order.
Despite
the names "Legacy" and "New Dynasty" - both types of SSDs
will both be around for the foreseeable future.
PCIe SSD examples
In
the
PCIe SSD market you
get both types of SSD. Some products are legacy while others are new dynasty.
And knowing which is which can help you comprehend some puzzling market
nuances.
You may think that products with superficially similar
performance envelopes like the
RamSan-20 from
Texas Memory Systems
and the ioDrive from
Fusion-io compete
head to head.
But that is rarely the case for most commercial end
users.
The RamSan-20 (which has an onboard offload
SSD controller) is in
the Legacy camp. It's a product which a user might retrofit to an existing bunch
of servers running existing apps.
The ioDrive is undoubtedly in the New
Dynasty camp - because it will usually be a factory fitted option supplied by
the server oem. Although you can use ioDrive's in some older servers - these
products work better with newer servers (with faster CPUs) because that's the
market they were designed for - with the
host CPU doing
the memory gymnastics traditionally done by an SSD resident hardware
controller.
The Legacy / New Dynasty way of looking at things works at
the next level up in the application hierarchy too.
A New Dynasty SSD
accelerated server (whether it's got a factory fitted PCIe ioDrive inside or
some SandForce driven
SAS SSDs) simply looks
to the external world like a faster server. A year or so after you've installed
a couple of hundred New Dynasty accelerated servers into your environment - you
may hit some new IOPS bottlenecks in another hot spot further up the data food
chain. In most user sites that bottleneck will be architected on a classic
storage network (SAN or
NAS) and the solution to
the next level of bottleneck will actually be a Legacy SSD - maybe even a RAM
SSD.
The RAM SSD
market (the oldest part of the enterprise SSD market) may - in my analysis
-paradoxically see a resurgence and continue growing for many years.
Although
lower priced flash SSDs killed off the entry level RAM SSD market - only RAM
SSDs have the fast latency and symmetric performance which can cope with the
increased data demands which will be created by bigger populations of flash SSD
accelerated servers.
And meanwhile - all that propaganda spewing out
from the flash SSD
market in the past 5 years has
educated users and
made the market more receptive to the idea of an SSD solution.
In the
old days
of the enterprise SSD market - pre 2005 - the server accelerator SSD was
parachuted into performance distressed customer sites as a previously
unlooked for expensive fix when all else had failed.
I'll talk more
about this new way of looking at enterprise SSDs - in future articles. | |
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| sugaring nand flash
for the enterprise |
When flash SSDs started to be used as
enterprise server accelerators in 2004 - competing
RAM SSD makers said
flash wasn't reliable
enough.
Since then flash has dominated the installed base of
enterprise SSD starting with SLC, followed by MLC, then a correction to eMLC
and now some SSD makers are saying TLC (x3) may be good enough.
But
it's not just the raw memory
type which determines the suitability of which flash can work reliably in
what type of enterprise SSD. The
controller IP and
cache architecture
can make a difference to the
endurance
of x5, x10, x20 - and I've even heard claims of x100...
That means TLC
(aka x3) - with the right SSD IP - may be as good as SLC in some types of
applications. And it costs a lot less and has higher capacity.
What do
you need to know?
Who are you going to believe? |
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... |
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Megabyte's enterprise
accelerator
had elements of both traditional and
futuristic design with
built-in
redundancy and seamless failover. | |
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| HA / FT
enterprise SSD arrays |
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| ..."The SSD
accelerator market should be viewed as a replacement for part of the server CPU
market. Not as a percentage of storage spend." |
| from the classic 2003 article -
could SSDs become a $10
Billion Market? | | |
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| How big was the
thinking in this SSD's design? |
The novel and the short story both have
their place in literature and the pages look exactly the same. But you know
from experience which works best in different situations and why.
When
it comes to SSDs - Big versus Small SSD architecture - is something which was
in the designer's mind. Even if they didn't think about it that way at the time.
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For designers, integrators,
end users and investors alike - understanding what follows from these simple
choices predicts a lot of important consequences. ...read the article | | | |
| . |
| 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 and
vendor's product datasheets and whitepapers.
Underlying all the
important aspects of SSD behavior are
11 key asymmetries
which arise from the intrinsic technologies and architecture inside the SSD.
Knowing that these symmetries exist, what they are, and judging how
your selected SSD compares will give you new insights into SSD
performance,
cost and
reliability.
There's
no such thing as - the perfect SSD - existing in the market today - but
the SSD symmetry list helps you to understand where any SSD in any memory
technology stands relative to the ideal. And it explains why deviations from the
ideal can matter. |
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| this way to the Petabyte
SSD |
In 2016 there will be
just 7 types of SSD in
the datacenter.
One of them doesn't exist yet - the bulk storage
SSD.
It will replace the last remaining strongholds of
hard drives in the
datacenter due to its unique combination of characteristics, low running costs
and operational advantages. |
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... |
The new model of the
datacenter - how we get from here to there - and the technical problems which
will need to be solved - are just some of the ideas explored in this
visionary article. | | | | |
