Re: [exim] Exim Performance / Server Performance

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Author: Phil Brutsche
Date:  
To: rootchaos
CC: exim-users
Subject: Re: [exim] Exim Performance / Server Performance
RootChaos wrote:
> Exim 4.30 (MySQL Database backend - Virtual Mailboxes)
> Amavisd-new
> F-PROT Antivirus
> Spamassassin
> Qpopper


Ugh. Qpopper.

> Hardware Config :-
>
> Dual Intel P4 2.8
> 2 GIG Ram
> 1 x 120 GIG IDE Hard Drive


Ugh. Single IDE hard drive.

I would replace Qpopper with something else - I prefer and recommend
Cyrus IMAP, but this is an existing installation with thousands of users
and the transition would require careful planning, to say the least.

Why is qpopper bad? See this link:
http://www.mailarchive.ca/lists/comp.mail.sendmail/2000-05/1783.html

I quote:

"The most likely bottleneck is qpopper I/O especially if your users have
large mailboxes that they are leaving on the server. qpopper copies the
entire mailbox from /var/mail to /var/pop (or wherever you've configured
it to go) for every POP connection."

The 1.0-stable tree of Dovecot should yield better performance and will
be able to serve your existing mailboxes.

As for the hard drive...

You would be well advised to redo your storage mechanism. You should
have *at least* a mirror for *everyting*. Your IMAP/POP3 storage
would best be placed on a RAID 10 or a RAID5 volume separate from the
OS. EIDE/SATA or SCSI is a decision I'll leave up to you.

Personally I would go 100% SCSI - 6 disks on a hardware RAID controller
with a decently-sized battery-backed cache: 2 mirrored for OS + 4 in
RAID10 for the data. I would also have a spare disk or two. Like I said,
the decision is up to you; other people will disagree with my
recommendations.

--

Phil Brutsche
phil@???