[Arm-netbook] A10 server dreamboard

[Gordan Bobic]

On 05/29/2012 11:51 PM, Henrik Nordström wrote:
> tis 2012-05-29 klockan 15:24 +0300 skrev Tsvetan Usunov - OLIMEX Ltd:
>
>
>> I've had interesting chat with Alejandro on the irc  about possible
>> use of A10 as fanless server unit.
>
> A10 would in theory do quite nicely as micro-server. But there is some
> major drawbacks when applying A10 to a long term product such as server
>
> a) No mainline kernel support. Each new kernel release requires
> significant effort.

This is an important issue. It isn't a problem if clean patches exist 
against the kernels that major distributions use, but it is still a lot 
of effort to keep the SoC maintained out of tree for what could be many 
years.

> b) It's SATA support is kind of secondary and not very well tested, with
> some worrying reports about instability and corruption. Don't quite have
> trust in it yet.
>
> c) It does NOT support SATA port multipliers which limits storage
> expansion capability considerably.

When you say it doesn't support it, do you mean it won't work at all, or 
do you mean it doesn't support FIS switching (and thus the performance 
will degrade as you plug in more disks into the multiplier)?

>> What do you think will be most useful (speak as performance not price)
>> for ARM embedded server with A10?
>> ok, ETHERNET is must, I guess HDMI and many USB ports etc are not
>> necessary in this case although they are build in and will not rise
>> the BOM significant
>
> For server usage HDMI is not neccesary, but as many USB you can fit is
> absolutely needed (i.e. OTG + 2xHOST). And if it also has HDMI then same
> device can be a multi-purpose device which is a big win.

For a standalong server *TX board, I agree. Not the case for blades, though.

>> cheap LiPo 1.4Ah backup battery for stand alone operation few hours
>> without main power supply instead to use costly UPS?
>
> Maybe. Having the option to connect battery is always nice. Esp if it
> can provide 5V output for a while to allow clean shutdown even with some
> disk attached. But not required.

You could perhaps use one of those 5.25" bay UPS-es? Keeps everything 
nice and generic.

>> RAM amount 1-2GB?
>> FLASH amount 4-8GB enough?
>
> 1GB ram is sufficient for an A10 class device. Actually for server usage
> 512 is sufficient as you don't need GPU/VPU/Framebuffer/2D Graphics
> engine so you can have a full 512 available. But 1GB is most likely
> optimal.

 From what's been said 1GB is the maximum, and at 512MB you rapidly lose 
the ability to have a product that distinguishes itself from the crowd.

>> size factor? what is the best concept to mount in rack?
>
> rack mounting a device like this? Naa..  building a 1U rack mountable
> box with a bunch of them maybe :)

Sure - rack mount stuff is good. :)
If it's a *TX board, I'd use one of the dual-board 1U cases. But a blade 
system would be better.

> Reasonably small board. And which can fit into standard available casing
> I think. I.e. like the VIA APC 8750.

If you want to go for tiny size, look at the CuBox's format.

>> advantage is clear, such server will have 4-5W power consumption i.e.
>> less electricity bill, and quiet as no fans
>
> fans may still be needed depending on what you add besides the CPU
> board.

Yeah, it's always interesting when you put an 8W disk next to a 2W SoC...

> there is already several products in this category. But most have far
> too little RAM to be interesting for real server usage.

Indeed, but some do already have 1GB (CuBox), and some are even in *TX 
form factor (SBC-A510).

Gordan