"Tory M Blue" <tmblue at gmail.com> writes:
> I've just started to make some changes to our slon environment and
> wanted to run something by the group, to decide if I'm buying myself
> anything or looking for trouble.
>
> Currently I have a 4 node system
>
> Master
> Slave
> Qslave1
> Qslave2
>
> (Qslaves are query only)
>
> Currently all 4 nodes talk to each other and at this point in time,
> I'm not sure why it was configured this way. I would think that it's a
> slight performance hit to have the Qservers talk to each other, when
> they will never exchange any data.
>
> So is there a reason for each node in a cluster to talk to each other,
> or will I be okay removing the communication  (Paths) between the 2
> Qslave servers?

It's preferable NOT to have a "full communications mesh," as that
leads (particularly as the number of nodes increases) to nodes opening
way more connections and doing way more DBMS work.

The *minimum* easy-to-determine[1] set of paths that you need is to
have a path from each subscriber to its provider, and
from each provider to its subscriber.

Thanks for asking; that gave me reason to mull it over in my head
again, and I think I now know what I want to write up in the docs on
this.

Notes:

[1]  This represents more than a "strict" minimum; the "strict" minimum
would involve having the mandatory path from each subscriber to its
provider (as above), plus a set of "spanning paths" to allow events to
get from the subscribers back to the origin.  The "minimal" form of
the latter *probably* is to have a path from each subscriber that is
not a provider that points back to the origin node.
-- 
"cbbrowne","@","linuxfinances.info"
http://linuxfinances.info/info/spiritual.html
Why are they called apartments, when they're all stuck together?