[wplug] Thoughts & Considerations for email server

[Edward Walter]

I ran a similar setup with courier, postfix, and SquirrelMail for a 
number of years (approx 4) on my network at home.  I used maildirs as 
the data store and occasionally ran into weird issues where mailboxes 
would seem to go stale (content wouldn't refresh in aa timely manner).  
I attributed this to mailbox size (number of messages) and the 
underlying hardware (old crappy hardware RAID 5 controller).  Setting up 
imapproxy made this a little better but never completely solved it.

If I were going to do this again, I'd probably select Cyrus IMAP instead 
(I believe it scales better).

Your users will probably come to hate SquirrelMail.  It's good for quick 
access when your traveling.  I wouldn't use it for everyday email access.

For your RAID setup, with 4 disks, I would look at RAID 10 or RAID 6 
instead of RAID 5.  With RAID 10, you'll get better performance than 
RAID 5.  With RAID 6, you can lose 2 disks and still be functional (same 
with RAID 10 if the disks aren't part of the same mirror pair).  There 
are a couple of issues with RAID 5.  First, the likelihood of losing a 
second disk is higher when rebuilding the array.  Second, with large 
disks, the rebuild time is longer (obviously) so the risk of a 
catastrophic failure is higher.  RAID 6 addresses this by maintaining 2 
parity bits (instead of one).

One other observation;  you're planning to provide 700 GB of space for 
7,000 users.  That works out to roughly 100 MB per user.  You're 
providing less storage than the free email services and (arguably) a 
lower quality interface for accessing mail.  I'm not trying to be 
critical but why do you expect this project to succeed?  It seems setup 
to fail (from a resource perspective).

-Ed Walter



Kevin Squire wrote:
> I just got word late Friday that my "little" server for student email
> will now be used for both student and parent email.  ($BIG_COMPANY just
> tried to extort $70,000 from use to renew for the 2007-2008 year - CFO
> not happy about it).
>
> This is the first launch of (1) us offering student email and (2) us
> hosting our own email server.  Since it is my responsibility, I am now a
> bit more nervous then before.  We just upped the accounts from ~4,000 to
> ~7,000.
>
> All the "bosses" know that I have never done anything at this scale, and
> they know that this year will most likely be a "test run".  I have put
> all my cards on the table, so I am not worried about my job, but I still
> want to make it as successful as possible.  This is really the first
> large scale deployment of OSS software, and I would really like to bring
> more in in the future. 
>
> Below I will list the hardware and software - I would love to hear any
> feedback from those with some experience.  Any horror stories, any
> tips/tricks, any thoughts/feelings about the setup, etc.  Any info would
> be appreciated.
>
> Server is a HP ProLiant ML310 G4 with 
>   - Dual-Core 3050 2.13 GHz
>   - 4GB ram
>   - 4 HDs in a RAID 5 array - totaling ~700GB storage
>
> Software is 
>   - Debian Stable
>   - Postfix/Courier with MySQL back-end
>   - SquirrelMail web interface (this yr we will only support webUI, we
> will not support other mail agents)
>   - imapproxy for proformance issues
>   - maildrop for quota and filtering
>   - amavis for clamAV and SpamAssassin 
>   - Probably a few other things I can't think of right now.
>
>
> Using a basic ISP style setup.  I used this write-up as a basic guide -
> http://workaround.org/articles/ispmail-sarge/ - did not follow it
> exactly, but pretty close.
>
> Again, I thank you for your time and your input.
>
>