Re: [Xen-users] AoE (Was: iscsi vs nfs for xen VMs)

[Simon Hobson <linux@xxxxxxxxxxxxxxxx>]

Adi Kriegisch wrote:

> What AoE actually does is sending a frame per block. Block size is 4K -- so
> no need for fragmentation. The overhead is pretty low, because we're
> talking about Ethernet frames.
> Most iSCSI issues I have seen are with reordering of packages due to
> transmission across several interfaces. So what most people recommend is to
> keep the number of interfaces to two. To keep performance up this means you
> have to use 10G, FC or similar which is quite expensive -- especially if
> you'd like to have a HA SAN network (HSRP and stuff like that is required).
>
> AoE does not suffer from those issues: Using 6 GBit interfaces is no
> problem at all, load balancing will happen automatically, as the load is
> distributed equally across all available interfaces. HA is very simple:
> just use two switches and connect one half of the interfaces to one switch
> and the other half to the other switch. (It is recommended to use switches
> that can do jumbo frames and flow control)
Getting somewhat off-topic, but I'm interested to know how AoE 
handles network errors ? I assume there is some handshake to make 
sure packets were delivered, rather than just "fire and forget" !
--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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