[ELDK] ATA over Ethernet (AoE) Root Partition?

Jason Hanna jason.m.hanna.at.coincident at gmail.com
Wed Oct 1 16:33:57 CEST 2008


On Wed, Oct 1, 2008 at 4:28 AM, Wolfgang Denk <wd at denx.de> wrote:
> Dear Jason,
>
> I haven't, but ...
>
>> Seems like this would be preferable to using NFS during development as
>> AoE should be the more efficient protocol.
>
> ... I would like to ask what makes you think that would be more
> efficient than NFS? The overhead for (UDP based) NFS is pretty low -
> just have a look at the code in net/nfs.c.
>

You might be right...the devil is probably in the details. At first
pass however ATA Over Ethernet looks quite appealing for the
development setup because it doesn't carry the overhead of the TCP/IP
stack. It's a non-routable protocol that operates directly on the
Ethernet layer. I've seen some references suggesting users are getting
faster throughput with AoE versus a tuned NFS system, but there are a
lot of variables to consider and I suspect any gains are somewhat
offset by the fact you're issuing more low-level commands. In case
anybody is interested, here's the protocol definition:

http://www.coraid.com/RESOURCES/AoE-Protocol-Definition

Because it's a SAN protocol it's also typically only accessed by a
single host at any time. A networked file system is probably more
embedded developer-friendly, but I'm sure there are some use cases
where AoE is more compelling.

>> Don't see any examples in the U-boot documentation referring to AoE, however.
>
> In U-Boot? There is no AoE support in U-Boot, yet. But patches are
> welcome :-)
>

I don't exactly know where to start, but I'll look into into what it might take.

Thanks,
-jmh


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