[Arm-netbook] EOMA server standard

[Gordan Bobic]

On 10/23/2012 06:09 PM, luke.leighton wrote:
> ok, right.  i've been talking to some companies and the need for a
> standard which covers data centres - e.g. has 10Gigabit Ethernet - has
> come up.
>
> it turns out that 10GBase-T is 500mhz and 16-way PAM over each of the
> 2-twisted-pairs that go onto a standard RJ-45.  so, *fast*, but also
> staggeringly power-hungry.  this 10GBase-T PHY IC has one variant at
> 2.4 watts and another at 6 watts:
>     http://www.solarflare.com/Ethernet-Controllers-LOMs
>
> so the question i'm raising is: what would people see as being the
> most appropriate general-purpose and lowest-common-denominator
> "upgradeable" interfaces to have on an EOMA standard?  and, what case
> would be good to re-use?
>
> for the pin-outs i figured that at least one 10GBase-T interface (8
> pins plus 8 GND spacers) would be acceptable, as would SATA-3 (4 pins
> plus 4 GND spacers).  that's 24 pins already (!).  PCI-Express 4x is
> 64 pins.  that's up to 88 *already*.  adding in USB3, it's not
> unreasonable to imagine this would be a 100-pin standard.
>
> so this is going to need some really careful thought.

Why on earth would anyone in the right state of mind even consider 
running 10G ethernet over copper? Every deployment I have seen to date 
is fibre based. 10G copper switches don't sound particularly plausible 
if you have to vent out 6W of heat per port.

If fibre is not an option for the chassis for some obscure reason, 
multiple gigabit connections (you have to have a built in gigabit switch 
anyway for each node) are a much more sensible option than 10Gb copper, 
and much cheaper and more versatile than fibre.

Gordan