

Facebook goes ARM with Calxeda - mtgx
http://semiaccurate.com/2013/01/16/facebook-goes-arm-with-calxeda-like-semiaccurate-reported-2-years-ago/

======
mtdev
This article is a little misleading in that it seems to indicate that FB will
trash Xeon servers and drop in ARM processors. Current ARM processors (SOC and
standalone silicon) have poor data throughput. You can mask this using media
accelerators, e.g. decode x264 video in the GPU so you have smooth playback
while saving some data bandwidth. ARMv8 (allegedly sampling in 2014-2015) will
double the AHB/CoreLink width and instruction size to 64 bits, but we are not
there yet. What is much more likely is that they will incorporate specialized
hardware using FPGA/ASIC and use ARM cores as supervisory modules. That way,
they can use a general purpose OS and use ARM tools to develop for the
supervisor module, and still get the data throughput of the custom controller.
This is how data processing is already done on 1080/2k/4k video streams.
Xilinx and likely Altera already provide FPGAs with hard ARM cores (in
addition to IP for soft cores) which makes it very easy to roll your own data
controller with an ARM core managing it. Makes a lot more sense for FB to go
this route for custom NAS boxes, possibly network switch/router hardware to
follow in Google's path.

~~~
dietrichepp
I didn't get the impression at all that Facebook was "dumping" Xeon, merely
that they were adding ARM.

Throughput is not really relevant. Throughput per unit power is better. ARM
manufacturers have been optimizing for power consumption and unit cost for a
long time, Intel has been optimizing for throughput and speed for a long time.
Both sides are aiming for the same target, from different angles. A "low
power" Xeon might be 40W for four cores, but the typical range is 60W - 140W.
Calxeda sells a sixteen-core, 20W ARM board. By these numbers, Xeon needs to
have 8x throughput of the ARM to beat it in throughput per watt.

Now, this is not entirely unreasonable. I've done benchmarking of my Core i5
against my Atom on an audio sample rate conversion library I wrote, and the
Core i5 has 6-7x the throughput of the Atom. So, I would believe you if you
said that a Xeon core is more than 8x as fast as an ARM core, and therefore
the throughput per watt is better. This is all guessing, based on one
benchmark I did for a library I wrote. I'm sure that Facebook has done some
experiments with the applications they'll actually be running on the ARM.

I'm not sure where you get the idea that these ARM computers will be centered
around specialized hardware, Calxeda's website only mentions general-purpose
hardware built around ARM cores.

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justincormack
As far as I can work out from the details released so far, this is basically a
standard backplane for "blade" (or microserver as they are now known) servers,
based on PCIe x8 so it is simple and cheap, which just happens to be more of
less what Calxeda was using anyway.

I can't work out yet if there is a standard way of attaching RAM as well I
don;t think so (yet).

It has taken an open source project to make blade servers standardised by the
look of it, should make the whole ecosystem much cheaper than the proprietary
systems.

It is not actually clear if Facebook has committed to ARM, although it would
not surprise me if they use some. But they have the option.

~~~
wmf
Each microserver has SO-DIMM slots for RAM.

Although this project is vaguely similar to blades, it isn't hot-swap, it
can't hold 2S/4S servers, and it's not clear how I/O consolidation will work.
So it's pretty different from existing blades.

~~~
justincormack
Hot swap would not be that hard to add to pcie but I don't think they care.
Sure there is ram per soc but the discussion implied they wanted to break it
up more longer term...

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WestCoastJustin
This reminded me of James Hamilton's blog post [1], about 48 Atom servers in
3U, or 624 servers into a standard 42U rack [2]. Shows you where the industry
is headed.

[1]
[http://perspectives.mvdirona.com/2012/12/11/MicroserverMarke...](http://perspectives.mvdirona.com/2012/12/11/MicroserverMarketHeatsUpIntelAtomS1200CentertonAnnouncement.aspx)

[2]
[http://www.quantaqct.com/en/01_product/02_detail.php?mid=27&...](http://www.quantaqct.com/en/01_product/02_detail.php?mid=27&sid=155&id=156&qs=94)

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gozzoo
Interesting news, but very poorly written article.

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stewie2
I hope there could be some ARM based cheap host service soon. some thing like
linode, but on an ARM, not on virtual machine.

~~~
wmf
What would be the advantage of such a service?

~~~
dietrichepp
Compared with virtualization, it would be more secure. If a dedicated ARM (or
Atom) microserver were competitive with mid-range VPS, people would buy it.

Virtualization is "leaky", there are esoteric attacks against other guests on
the same host that allow attackers to obtain encryption keys. Last time I
checked, the mitigation strategy was to move to dedicated hardware.

I doubt dedicated microservers will be competetive with VPS for a while yet
because you can't oversell them.

~~~
EwanToo
Dedicated Intel Atom hardware is already competitive with VPS services, for
example you can see the Kimsufi stuff from OVH

<https://www.ovh.co.uk/dedicated_servers/kimsufi.xml>

Hosted in the USA or France, prices from £8.99 a month ($12?) for an Atom
server with 2GB of RAM.

------
Ecio78
related post <http://news.ycombinator.com/item?id=5071583>

