dovecot - Jun 2012 - Hardware infrastructure for email system

Hi,

I'm currently (re-)planning my email setup and have been doing some 
research. I have done some searches and read several threads in the 
areas of my questions here. While there are some that come close I 
haven't yet been able to get all my questions answered.

I currently run a postfix, dovecot & roundcube setup and have about 2000 
active accounts. I have a separate SMTP server for outbound mail and 
auth is done against a separate LDAP server. In front of the POP/IMAP 
server I have another SMTP (4 in parallel actually) server that receives 
and filters inbound mail through a company specific, proprietary filter 
before the mail hits the POP/IMAP server. LDAP & SMTP servers are ESXi VMs.

So right now both dovecot and roundcube run on the same box which is a 
Dell PE2950 with dual quad-core Xeon, 16GB RAM and 6 1TB disks in RAID 
6, so only local storage using maildir.  So far it's been holding up 
fine, but it's beginning to show signs of overload now. I also expect an 
increase in users over the next few months up to somewhere between 10 - 
20,000 mail boxes. Hence the re-planning.

My first priority in redesigning my setup is reliability. I definitely 
need something fail-save and as close to always on as possible. Next is 
performance. And while the budget is of course limited for the moment 
I'm setting that aside and will worry about that when the time comes.

Now here is my question(s):

In order to support up to 20,000 mailboxes (distributed over several 
times-zones so they won't all be used at the same time) with a very 
reliable service with good performance, what do I actually need?

Do I need(ul) SAN or is it just a "would be nice to have"? If yes, why
and what would be appropriate for my needs? Or will a setup with a few 
more servers like the ones I already have, using something like DRBD and 
distributing services (imap, http, spamd etc) onto different boxes do?

I know I have more reading to do on all the different options out there, 
but would like some input from people that have experience in this area 
so I can focus on the stuff that's right for my situation.

Michael

Michael,

* Michael Wessel <michael at
think-for-yourself.org>:
> I'm currently (re-)planning my email setup and have been doing some
> research. I have done some searches and read several threads in the
> areas of my questions here. While there are some that come close I
> haven't yet been able to get all my questions answered.
> 
> I currently run a postfix, dovecot & roundcube setup and have about
> 2000 active accounts. I have a separate SMTP server for outbound
> mail and auth is done against a separate LDAP server. In front of
> the POP/IMAP server I have another SMTP (4 in parallel actually)
> server that receives and filters inbound mail through a company
> specific, proprietary filter before the mail hits the POP/IMAP
> server. LDAP & SMTP servers are ESXi VMs.
Do people use 'real' mail clients to connect and IDLE too?

> So right now both dovecot and roundcube run on the same box which is
> a Dell PE2950 with dual quad-core Xeon, 16GB RAM and 6 1TB disks in
> RAID 6, so only local storage using maildir.  So far it's been
> holding up fine, but it's beginning to show signs of overload now. I
> also expect an increase in users over the next few months up to
> somewhere between 10 - 20,000 mail boxes. Hence the re-planning.
> 
> My first priority in redesigning my setup is reliability. I
> definitely need something fail-save and as close to always on as
> possible. Next is performance. And while the budget is of course
> limited for the moment I'm setting that aside and will worry about
> that when the time comes.
> 
> Now here is my question(s):
> 
> In order to support up to 20,000 mailboxes (distributed over several
> times-zones so they won't all be used at the same time) with a very
> reliable service with good performance, what do I actually need?
> 
> Do I need(ul) SAN or is it just a "would be nice to have"? If
yes,
> why and what would be appropriate for my needs? Or will a setup with
> a few more servers like the ones I already have, using something
> like DRBD and distributing services (imap, http, spamd etc) onto
> different boxes do?
Will the server enforce quota? 

What will be the average mailbox size?

Do people share content e.g. mailings with attachments that go out to all
recipients? 

What might be the maximum number of clients using the server at one time?

Will all users use the same client product e.g. roundcube?

What's your backup strategy? What do you use to backup mailboxes?

p at rick

-- 
state of mind ()

http://www.state-of-mind.de

Franziskanerstra?e 15      Telefon +49 89 3090 4664
81669 M?nchen              Telefax +49 89 3090 4666

Amtsgericht M?nchen        Partnerschaftsregister PR 563

Am 23.06.2012 11:20, schrieb Michael Wessel:
> So right now both dovecot and roundcube run on the same box which is a
> Dell PE2950 with dual quad-core Xeon, 16GB RAM and 6 1TB disks in RAID
> 6, so only local storage using maildir.  So far it's been holding up
> fine, but it's beginning to show signs of overload now. I also expect
an
> increase in users over the next few months up to somewhere between 10 -
> 20,000 mail boxes. Hence the re-planning.
you should ask for  paid support
at Timo , or some other dovcot geeks near you
-- 
Best Regards
MfG Robert Schetterer

>
> I'm currently (re-)planning my email setup and have been doing some
research.
> I have done some searches and read several threads in the areas of my 
> questions here. While there are some that come close I haven't yet been
able
> to get all my questions answered.
>
> I currently run a postfix, dovecot & roundcube setup and have about
2000
> active accounts. I have a separate SMTP server for outbound mail and auth
is
> done against a separate LDAP server. In front of the POP/IMAP server I have
> another SMTP (4 in parallel actually) server that receives and filters 
> inbound mail through a company specific, proprietary filter before the mail
> hits the POP/IMAP server. LDAP & SMTP servers are ESXi VMs.

it is already enormous overshoot in hardware specs. And i do not really 
catch why you have "4 in parallel" servers.

And finally i cannot understand this dividing of servers just to merging 
it back using VMWare.

Finally i would recommend to get rid of RAID6. It's terribly slow on 
writes and writes are common on mail server.

Buy cheapest but largest SATA drive and use RAID1 (or RAID1+0) setup.