[Dovecot] Hardware infrastructure for email system

[Patrick Ben Koetter]

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

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