[PLUG] Re: Mail server options for OSX?

D. Cooper Stevenson cstevens at gencom.us
Mon Apr 25 19:49:24 UTC 2005


John,

I can offer an overview of things to look for when determining
performance bottlenecks. The dynamic is similiar to diagnosing server or
PC bottlenecks--say a "performance diagnostic plus" as you've now
extended the problem to include potential networking issues.

I generally start from the core outward. This means the processor load
and memory usage. Is the CPU working hard to process the emails? This
can happen if your mail server not only delivers the mail to the local
filesystem but also processes the mail for spam and viruses.

Does the server have enough memory? If the server is swapping processes
to swap disk space, you're basically gauranteed a chronic performance
problem.

Is the mass storage subsystem up to the task? Think about moving the
storage from a single drive if applicable to a striped (and mirrored)
RAID 0+1 array.

How about bandwidth? Does your server have the connectivity to quickly
send and receive emails so that it may get on with the filesystem
delivery phase or is the server jammed waiting to trickle out? Perhaps
your mail server (shudder for security reasons) also doubles as a
file/print/application server. Is your network subsystem tied up with
these tasks as well? 

Is the mail process set to a high enough priority or is it relegated to
a "when there's time leftover" status?

Moving on to the software...

Does the mail server have a lenghty queue of backlogged mail that it is
constantly trying to process? This can happen by emails that cannot be
delivered as the remote server requires reverse DNS lookups to be
delivered. Since there is not a '504' error meaning definate failure,
the server keeps trying. For all of these issues, look at your logs for
the 'delay=' entries to determine how long the mail took to process.
Larger backlogs means more work for the server and hence fewer resources
for doing the "real work."

Overall, I think a migration to a higher capacity server is usually the
best route in a case where "obvious" things do not yield good results.
My view is that while you don't want to just throw hardware at the
problem, holistically it's better to move to a platform that will give
you room to breath looking forward. It's also worthy of consideration
that  the prospects of tweaking an old server to death may only yield
receive a minimum of benefit. 

As your endeavors continue and the system renders new information we can
home in on what the bottleneck is.


-Coop

On Mon, 2005-04-25 at 10:08 -0700, john morgali wrote:

> Sorry if I was too vague, and I may yet need to refine
> my question as this thread goes on. 
> 
> Well, we have several years worth of emails in it, and
> we are using it also as an email archive that we can
> browse.  Lately it seems to have noticably slowed down
> in its performance.  We cant seem to find any problems
> with it, other than it is just slow. 
> 
> More questions for you guys...
> Do you have experience with this type of setup? Have
> you used this client and others, and how does it
> compare?  What are the pros and cons of it? How well
> is it documented? 
> 
> John
> 
> 
> --- Wil Cooley <wcooley at nakedape.cc> wrote:
> 
> > On Mon, 2005-04-25 at 09:51 -0700, john morgali
> > wrote:
> > > Not sure if this is too off topic for this forum,
> > but
> > > I thought I would toss it out.  
> > > 
> > > The company I work for is currently an almost
> > entirely
> > > Mac OSX office, and is looking for an alternative
> > to
> > > the current mail server that they are using.  It
> > is
> > > Cyrus running on OS 10.3.8.
> > 
> > What's wrong with Cyrus?
> > 
> > Wil
> > -- 
> > Wil Cooley                                
> > wcooley at nakedape.cc
> > Naked Ape Consulting                       
> > http://nakedape.cc
> > * * * * Linux, UNIX, Networking and Security
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