State Disks:- Pushing the Envelope in Blade Server Design - article by BiTMICRO|
terms of power consumption, mechanical hard disks typically devour around 500mA
while flash SSDs consume a mere 50mA. The difference may seem insignificant in
small enterprise apps, but for huge data farms, the cost savings become
apparent. This further enhances the blade server's advantage over proprietary
systems with regard to operational costs. The reliable performance of
mechanical disk drives can only be ensured if these drives operate within
specified temperature ranges. As drive manufacturers introduce newer models
featuring spindle speeds as high as 15,000 RPM, cooling has emerged as a major
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DSP Cards for Sun|
Digital Signal Processors (DSPs) are typically
optimised for performing Fast Fourier Transforms (FFTs) in real-time. Their
characteristics include fast multiply and bit shifting performance, predictable
instruction execution times, and direct on chip I/O ports.
DSP chip was the Intel 2920 introduced in 1979. At a time when all other
processors only had 8 bit intsruction sets, the 2920 had an impressive looking
24 bit word. However early generations of DSP were aimed at voice processing in
the telecoms market, and Intel's MOS processing technologies were optimised for
high logic density rather than analog capability, so I remember thinking that
the onchip ADCs on early Intel processors such as the 8022 etc were rubbish.
Plainly other engineers were underimpressed too, because Intel never became
successful in the DSP market, and exited the low end DSP market soon after.
However, some systems vendors used Intel's i860 graphics optimised RISC
processor as a DSP engine.
Many other semiconductor manufacturers
entered the high volume DSP market, and probably the most successful has been
DSP cards started appearing for use in Sun systems
in the mid 1980s before Sun launched its first SPARC processor. A popular demo
my company used to run at Sun Expos included a Sun-3 (68020) processor running
with an Analogic array processor. The demo started with a photo of a desert
scene which seemingly included nothing more than sand and rocks. Running the
pattern recognition software eventually stripped away the camouflage to reveal a
hidden tank. Another, less politically correct version of this demo involved a
model wearing a string vest.
Although SPARC processors have adequate
DSP performance, they are uneconomic for use in applications which require large
numbers of DSP channels. So most DSP cards for SPARC systems actually use a
variety of other processors to implement the DSP functionality.
typical application for SPARC hosted DSP systems is intelligence gathering. For
example millions of telephone voice lines are analysed in real-time by banks of
DSPs which trigger on key words and phrases. For example the word "bomb".
The technology is so good nowadays, that the software generated report which
accompanies these intercepts can even rocognise the voice of target suspects.
biggest commercial application for DSPs is still the telecoms market. DSPs
implement the hands free voice based input for value added services implemented
by some PTTs. However, the most impressive demo I saw recently was in my wife's
combined PDA and cellphone. If she says "phone Ann" - the PDA knows
who Ann is, looks up the phone number and dials it.
SPARC systems have
been too expensive to get used much in industry, but a typical industrial
application of DSP technology is monitoring rotating machinery to detect wear
out and predict failures before they become catastrophic.
systems are still widely used in research labs, although the end products such
as in car noise cancellation (based on earlier research into making quiet
helicopters) will typically be implemented by something a lot cheaper and
smaller than a workstation.