[CentOS] Large scale Postfix/Cyrus email system for 100,000+ users

Christopher Chan christopher at ias.com.hk
Thu Oct 25 04:46:48 UTC 2007

> Heck, I see lots of circles where they wouldn't trust mysql for an
> enterprise application so it seems clear that you are not talking about
> stability or performance but rather familiarity and the amount of trust
> you have in what you know.

Let's see, mysql crashes (elcheapo hardware, happens once in a while) 
but tables containing hundreds of thousands of rows survive intact on 
reboot. Could you do that with postgresql? Nah. Did I mention you can 
just copy myisam files to another box and even if it has another OS so 
long as they are on the same cpu platform and use it without trouble? 
Add solid replication and hey, it is had to beat for the price (free). 
mysql is stable within the limits it can handle. It can run for months 
without trouble. A dual PIII box with 1GB of RAM, can handle the peak 
load of 6 postfix boxes that are configured to handle 800 simultaneous 
connections  (okay, most of those connections rarely made it to the 
check user stage so let's put ten percent as successful: 800*6*3[bare 
minimum in the modified postfix]*0.1 = 1440) and not break a sweat only 
chewing 10-20% of available cpu resources. Mind you, this is only 
possible due to postfix proxy connection pooling otherwise mysql will be 
bringing the box to its knees if postfix had to open and close tcp 
connections for each set of queries.

I guess I should try to make a test against openldap/fedoraDS and see 
how they fare.

> I would expect openldap to blow the doors off a mysql db but what do I
> know? I deal in circles < 100 user accounts (small businesses).

Yeah, seeing mysql in action in a service provider that now handles over 
40 million mailboxes (over 30 million when I joined and worked there) 
sure puts a few points in for it in simple table environments.

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