My experiences with spread were less than stellar, but instead of
going into that, I'll just give a piece of advice. Spread first tries
to communicate using multicast, and then falls back to broadcasting.
At my hosting provider, since their equipment didn't support
multicast, this meant that, even though communications were only going
between two computers and did not need to be broadcast to everyone,
all communications were being broadcast to everyone on the subnet. It
didn't take long before my hosting provider null routed my server. You
can override this behaviour by telling spread to communicate using
unicast, but this only works if there is only one destination for each
source piece of information.

Just something to keep in mind
-Gabe

On Thu, Sep 24, 2009 at 4:04 PM, Barry Abrahamson <barry@automattic.com> wrote:
>
> On Sep 17, 2009, at 5:49 AM, John Moore wrote:
>
>> It certainly does, thanks! Could I trouble you to explain a little more
>> about your use of Wackamole and Spread? I've not used either of them before.
>
> There is a How-to here:
>
> http://www.howtoforge.com/setting-up-a-high-availability-load-balancer-with-haproxy-wackamole-spread-on-debian-etch-p2
>
> You are just using nginx instead of HAProxy, but the Wackamole and Spread
> portion still applies.
>
> Scalable Internet Architectures (
> http://www.amazon.com/Scalable-Internet-Architectures-Theo-Schlossnagle/dp/067232699X )
> also has a section on how this works.
>
>> Also, is there any reason why a hosting company would have problems with
>> such a setup (i.e., this won't be running in our hardware on our premises,
>> but we have full control of Linux servers).
>
> Yes, you have to be a little careful here and ask questions up front.  A lot
> of hosting companies segment their switches such that each port is it's own
> VLAN which means you can't "float" IPs between ports which is what you need
> for this to work.  If you tell your hosting company what you are trying to
> do and tell them that you need to be able to have IPs which are
> programmatically moved between switch ports they should be able to tell you
> if this is possible or not.  Some hosts may require you have some sort of
> "private rack" or other upgrade to make this possible.
>
> Barry
>
> --
> Barry Abrahamson | Systems Wrangler | Automattic
> Blog: http://barry.wordpress.com
>
>
>
>
>