Date: 28 Nov 2001 08:58:51 +0100 From: Simon J Mudd <sjmudd@pobox.com> To: freebsd-isp@freebsd.org Subject: Re: Mail server (Sendmail) benchmarking Message-ID: <86r8qj498k.fsf@unicorn.ea4els.ampr.org> In-Reply-To: mark@work.drapple.com's message of "Wed, 28 Nov 2001 00:14:03 %2B0000 (UTC)" References: <XFMail.011127161336.mark@work.drapple.com>
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mark@work.drapple.com (Mark Hartley) writes: > I'm nearing the deployment phase for a project I'm working on that will involve > the sending of a very large number of relatively small (2k-5k) emails (probably > like 500,000 or more daily). Just so you know, this is NOT for any kind of a > spamming site. I'm just curious if anyone has some estimations as to about how > many emails I can reasonably expect one machine running FreeBSD 4.4-SECURE (or > whatever that branch is being called now) with Sendmail to be able to send in a > day. The machine(s) I'm looking at will be P3-933Mhz with 1GB of RAM. My main > question is whether I will need to throw more than one machine at this. > > I've done some calculations, and 500,000 emails at 5k each is 2.5GB/day. > Dividing that by 86400 (# of seconds/day) I get 28935 bytes/second, but I am > promised by the client that I'll have the bandwidth I need, so I'm just mostly > wondering if the machine will be the limiting factor, or will bandwidth be the > issue? > > > I'm asking in -isp because this is where I assume the heaviest use of > mailservers would be in an ISP or similar situation. If this isn't the right > forum, I can ask it in -questions but I thought the people in -isp would have > more similar experience to what I'm asking. > > Anyone with any numbers they would be willing to share with me would be greatly > appreciated. Someone else has mentioned postfix as a faster alternative. The other thing which will make a large difference is your disk I/O bandwidth as mail servers are nearly always disk I/O bound not CPU bound. I think this will be equally true for an outgoing mail server as every time a message is sent to a recipient information on disk has to be written to indicate the message has been sent, and also the fact has to be written to syslog. It's been reported to help enormously to have syslog writing to a different disk from the disk used for the mail spool. I would guess that this is likely to be the case in your situation. I think finally you will find the Internet much slower than you expect, even if you have sufficient bandwidth, as some mail servers are very slow and this can slow down the overall sending rates by a significant amount. I'd suggest you ask on postfix-users, sendmail's mailing list, or even qmail's mailing list. Brad Knowles also had a document somewhere on tuning mail servers for heavy load. Take a look at http://linuxperf.nl.linux.org/mailserving/ He also uses FreeBSD and I'm sure you'll find the paper useful. Simon -- Simon J Mudd, Tel: +34-91-408 4878, Mobile: +34-605-085 219 Madrid, Spain. email: sjmudd@pobox.com, Postfix RPM Packager To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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