[CentOS] Filesystem for Maildir

Fri Nov 30 07:55:07 UTC 2007
Christopher Chan <christopher at ias.com.hk>

>>> Very.  We have a single Linux box facing the Internet which
>>> runs everything through postfix, amavisd, and clamav to weed out
>>> the phishing and worms that attack the Microsoft virus, Windows,
>>> then hands off messages that pass to the internal cluster using
>>> round-robin DNS as the poor-mans load balancer.  This box runs
>>> with a load average less than 1.00 most of the time, rejects
>>> close to 2 million messages a day on IP related tests, passing
>>> about a half-million through to the internal servers which do the
>>> spamassassin checking and delivery to the user's mail stores.
>> What processing and i/o power do you have on that box and how much RAM? 
>> For the front end boxes, I had about 20-30 dual PIII 800Mhz boxes with 
>> two SCSI disks and 1GB worth of RAM. They reject close to 180 million 
>> messages based on access and ip rules, header and body checks (so 
>> nothing cpu heavy) and they pass on about 3 million for routing or 
>> further processing.
> The border MX machine is running a Intel(R) Pentium(R) 4 CPU 3.20GHz, seen
> as two processors in /proc/cpuinfo with 6389.76 bogomips.  It has 2GB RAM,
> and currently has a load average of 0.24 reported by top.

I guess that is plenty for one third the volume of rejects one of those 
dual PIII boxes handled...but then your box handles five times as many 
deliveries and therefore scans...

> The hard drive is a 40GB WDC WD400JD-19LS SATA which isn't anything special
> by any means.  It's running SLES9, installed in February 2006.  Uptime is
> only 356 days as it had to be rebooted to move things around in the rack.

You make sure emails never queue eh?

> The machines handling mail deliver in the cluster vary.  The first one I
> checked has an Intel(R) Celeron(R) CPU 2.66GHz with 1GB of RAM.  These too
> have pretty vanilla SATA drives.
> The main server with the home directories has an Intel(R) Pentium(R) 4 CPU
> 3.00GHz with no SMP, 2GB RAM, and several SATA drives.
> The border MX isn't beginning to breath hard handling the IP access rules,
> postfix, amavisd, and clamav.  We have seen very even distribution amongst
> the delivery machines in the cluster using nothing more for load balancing
> than dnscache from djbdns for a single hostname on the private internal
> 10/100 LAN.

Heh, I cannot imagine any other software for dns caching.

> The attached image shows the size of the mail queues on each of the 4
> machines every fifteen minutes since midnight yesterday.  This peaks
> shortly after midnight when daily security scans and other maintenance jobs
> are running.
> The load averages on these cluster machines rarely gets over 1.00.

The only times I had high load averages was when sendmail was in and 
when we are under bounce floods/ddos.

I guess this is the cheapest and most efficient way to do email.