scaling of DNS & mail servers

Kevin Darcy kcd at
Fri Mar 30 21:52:36 UTC 2001

Brad Knowles wrote:

> At 10:42 AM -0500 3/30/01, Thomas Duterme wrote:
> >  Just a quick question. I have a series of small qmail servers (6 of
> >  'em so far) and our organzation is scaling mail linearly for now.
> >  (I don't see us getting above 6 any time soon though...)
> >
> >  My question: each of these mail servers is a pretty low end box
> >  (PIII- 800, 256 K RAM, pizza box server).  In the past, I had them
> >  all pointing to my slave server (a nicer Dell 4300 512 RAM 600 CPU
> >  server).  But these boxes are now being used by marketing for
> >  promotions to our user base (a series of in-house lists)
>         In scaling mail servers, CPU is probably of least importance.
> Next least important is RAM.  Of most importance is the disk
> subsystem configuration, and the configuration of the filesystem on
> top of the disk subsystem.

I would have to concur heartily with that. I was under the impression until
relatively recently that CPU and memory were roughly as important to a mail
server as disk, but once our message volumes skyrocketed (post-merger), it
became quickly apparent that disk I/O was by far the main bottleneck,
especially in backlogged situations. I've already tweaked the filesystem
configuration about as much as it can be tweaked; now I'm looking to get my
mail relays onto a SAN/RAID of some sort...

- Kevin

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