hardware sizing for a large mail installation?

Mark Blackman mark at exonetric.com
Thu Sep 30 11:25:05 EDT 2004

On 30 Sep 2004, at 15:55, Oliver Falk wrote:

>>> Someone on the linuxmanagers list suggested I post my
>>> question here, so here goes:
>>> I'm looking for pointers (past experience in particular)
>>> for sizing a mail
>>> server for a large-ish mail install based on postfix, cyrus,
>>> amavisd-new,
>>> clamav, spamassassin, and web mail (most likely imp) serving around
>>> 100k
>>> mailboxes.  I estimate I'll need to be able to pass through
>>> the whole
>>> chain around 40msgs/sec continuously to be on the safe side.  If
>>> possible,
>>> I'd like to do this on a single server.  Cyrus murder
>>> probably isn't an
>>> option, but I think I could swing a separate box to do the content
>>> filtering.  Would, say, a 4-cpu Xeon with ~8GB RAM suffice for the
>>> MTA/IMAP combination?
>> I/O, I/O, I/O -- it's off to work we go!!
>> mail systems need primarily disk bandwidth. Get a killer disk
>> array (fibre-channel or SCSI) and that will keep you happy.
>> The Xeon is nice, but it's disk bandwidth you *need*. I can
>> recommend the StorageTek D-series disk systems, but a bit expensive.
> That's not fully correct. Yes, it's true that mail systems need
> primarily disk bandwith. But if you run - as he pointed out he will -
> spamassassin, amavisd, clamav and so on, you will also need a lot of 
> power and Memory, especially if you have many users who get a lot of
> mail.

he seemed willing to offload that to another box, so I chose not
to cover that point and his box does seem more than adequate (if
properly utilized) for most content scanning.

I should have made that point explicitly of course.


> My setup for about 1200 users (~ 60000 - 70000 mails/day):
> * Some IBM machine
> * 2 GB RAM
> * Dual-Xeon (2.66 GHz)
> * 100 GB Harddisk (SCSI 5 with IBM ServeRAID Controller)
> That setup is OK, but there's allready more memory and larger hardisks
> on our wishlist. :-)
> Best,
>  Oliver

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