Re: How many routers should i use?

[Tom <tom@sdf.com>]

On Wed, 22 Oct 1997, Matti Aarnio wrote:

> > Hi all!
> > 
> > I am running a server that receives only email for 'somedomain.com', which
> > has an MX with preference 0 to that server.
> > 
> > This server ONLY receives and routes messages for that domain, which has a
> > *very* slow connection to the Internet, it's outside the US, where my ZMailer
> > server is located.
> > 
> > I have noticed that increasing the router processes from 4 to 8 has 
> > improved the performance, but i was wondering that since all messages from
> > this ZMailer server go to one domain (in fact only to one server at 
> > 'somedomain.com'), maybe increasing the number o routers to 12 or even more
> > will help? what would be the drawbacks if any at all?
> 
> 	Without knowing all of your details it is a bit difficult to
> 	tell exactly, but on overall this sounds like your system is
> 	doing DNS lookups at the routing phase, and those lookups do
> 	take considerable time.

  Again, not much has been said about the details on this persons mail
server... but the time to deliver a single message will drop when there
are more routers because the incoming queue is scanned more often.  Could
be what is happening here, as this the system in question is described to
be quite small.

  Zmailer does better when handling a lot of e-mail that is very evenly
distributed.

  Also, the number of routers that you run is also a form of load control.
If you get hit by a big burst of e-mail, the system will never try to
overcommit itself (assuming that you are not running too many routers).
On other mail servers, this can be a big, big problem.

...

> 	/Matti Aarnio <mea@nic.funet.fi>
> 		(2.99.49p8 pre-release tests now running at SPARC Solaris,
> 		 maybe will complete them tomorrow, and do release; presuming
> 		 no snags creep up..)

Tom