
Intel SSD 750 PCIe SSD Review: NVMe for the Client - fraXis
http://www.anandtech.com/show/9090/intel-ssd-750-pcie-ssd-review-nvme-for-the-client
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nitrogen
The 1.2TB model uses _22 watts_ for writing at 1200MB/s (54MB per second per
watt). I guess performance comes at a power cost.

As a comparison, the 1TB Samsung 850 Evo uses 5.7W maximum for writing at
520MB/s (91MB per second per watt).

~~~
tlb
In fact it's generally true that for a given architecture and silicon
technology, power increases as the square of speed.

~~~
tcas
It's usually voltage as the square factor for CMOS. The equation I remember
from VLSI is:

    
    
      Power = (Load Capacitance) * (Voltage)^2 * (Frequency)
    

In order to run at a faster speed you frequently have to increase your core
voltage which causes a square increase.

~~~
jrockway
Incidentally 1 farad * 1 volt ^ 2 * 1/s is 1 watt. So this formula seems
accurate :)

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derekp7
Does this remind anyone of the "Hard Card", from Plus Development? They were
3.5" hard drives mounted on an ISA card way back in the day. It's funny how
technology is sometimes cyclical.

~~~
bhauer
Ha, indeed! I had a 20 MB Hard Card in my 12 MHz 286.

Both those numbers are but a quaint memory.

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mtanski
Ugh, I really wish the marketing people would pick different name for this
evolution of SSD drives then NVMe. At least the NVM part stating: Non-Volatile
Memory.

The current iteration of what we call NVM is just SSD on PCIe busses so they
are not bound by the speed of SATA/SAS controllers.

Maybe it's just me but when I think NVM I think of Non-Volatile Memory
something like RAM that doesn't go blank when you hit the power button. And
like RAM can be mapped into (kernel or user) address space. And access to them
go through processor caches (L2 or L3) strait into NVM.

The current SSD+ drives very much behave like the block devices of the old,
just with a different host interface. Most importantly they can't be directly
memory mapped without going through the page cache. That still leaves a lot of
performance on the table (double copy, requiring RAM for page cache versus
working set).

~~~
nitrogen
_Most importantly they can 't be directly memory mapped without going through
the page cache._

It's been _ages_ since I last did anything with PCI MMIO, but it was
definitely possible to map PCI devices' own memory into a process's address
space using /dev/mem, and into kernel space as well. Is there no longer an
equivalent concept for PCIe? Or was MMIO always attached to real RAM?

~~~
wmf
MMIO still exists but memory-mapping NAND flash isn't a good idea. Stalling
the processor for ~50 us on a cache miss is likely to lead to horrible
performance.

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imaginenore
Why are PCIe SSD drives so much more expensive per GB compared to the SATA
ones?

1TB SSD is now around $350-360 on Amazon.

~~~
wmf
Because their performance is much higher.

~~~
imaginenore
I'm pretty sure SATA SSD performance is bottlenecked by the SATA bandwidth.
It's the same flash inside.

~~~
jgeorge
Perhaps, but the PCI card also contains it's own controller instead of using
the existing SATA controller in the box. Not a complete justification for the
added cost, but even if the flash is the same, getting it connected is more
hardware than a SATA device needs.

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vladtaltos
idle power consumption: 4 Watts - way too much for my taste... I can
understand it needing 22 Watts during high speed writes but why this much
during staying idle ?

for comparison I checked my external 2TB WD Passport 0820 harddisk - it uses
2.11 Watts when streaming HD video...

~~~
kileywm
I agree, that's some high idle power consumption. If I had to hazard a guess,
it's the controller aggressively maintaining the charge of the flash cells
[1]. Samsung released a fix, not too long ago, for a bug with flash cells
losing charge for their 840 and 840 Evo SSD line [2], so I imagine it's a
delicate process to get right. Are the other NAND controllers less aggressive
and/or more efficient with this process? I don't know. I assume it's the same
flash cells as the SATA drives but with a PCIe-oriented controller, so I
hardly expect them to lose charge any faster than the SATA counterparts.

[1] [http://www.purestorage.com/resources/introduction-to-
flash-m...](http://www.purestorage.com/resources/introduction-to-flash-
memory.html)

[2] [http://www.anandtech.com/show/8617/samsung-releases-
firmware...](http://www.anandtech.com/show/8617/samsung-releases-firmware-
update-to-fix-the-ssd-840-evo-read-performance-bug)

~~~
yohui
That was due to the TLC NAND Samsung used, correct? More cost-effective but
not as durable as MLC NAND (which is what most SSDs, including this new Intel
drive, use).

Incidentally, while Samsung did release a firmware update for the 840 EVO to
mitigate the problem, AFAIK they never fixed the original 840. (840 Pro owners
need not worry, as it used MLC NAND and was not affected.)

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rasz_pl
Wow. Pretty me too product from Intel. They even priced and sized it to not
clash with Samsung, because it has nothing to make you pick it over SM951.

Not to mention you can cram SM951 into a laptop.

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tracker1
Want!

~~~
jsight
That's an understatement. It's unbelievable to me how quickly we have moved
from <100MB/sec drives being the norm to (relatively) inexpensive 1000+MB/sec
drives with incredibly fast seek times.

Now if only the laptop manufacturers would include SSDs in more mainstream
models. It's depressing walking into the average computer retailer and seeing
practically every shelf stuffed with slow HDs and salesmen trying to pitch the
huge importance of minor differences in processor speed.

~~~
jseliger
_It 's depressing walking into the average computer retailer and seeing
practically every shelf stuffed with slow HDs and salesmen trying to pitch the
huge importance of minor differences in processor speed_

As far as I can tell the computer market is bifurcating or has bifurcated into
people who give a shit about their experience and will pay for better (in
which case they tend to buy Apple, or some select PC brands like Lenovo (until
the certificate fiasco) or the Dell XPS 13"), and people who buy solely on
price. I can't imagine many sophisticated buyers going through a conventional
retail store, and, furthermore, if price is the primary consideration then
saying "It's a big drive and a cheap computer!" is better than trying to
explain why an SSD is $50 more or whatever.

~~~
yuhong
_I can 't imagine many sophisticated buyers going through a conventional
retail store_

Currently, but would it not be possible to fix them? How profitable are SSDs
for example?

