Date: Fri, 23 Feb 2001 22:49:11 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Daniel Frazier" <dfrazier@magpage.com> Cc: <questions@FreeBSD.ORG> Subject: RE: kernel optimizations for an smp mail server... Message-ID: <003601c09e2d$e50e2400$1401a8c0@tedm.placo.com> In-Reply-To: <3A96A568.66EBF9FE@magpage.com>
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This is entirely dependent on how many _simultaneous_ accesses the box has. Since you haven't told us this, I'll attempt to calculate it here: If your a dialup house running 10-1 on modems, you have 1,000 modems deployed. Your average user gets 10 messages a day with an average message size of 20K, and checks mail an average of once every 2 days, thus pulling a half-meg at a time. On V.90 this takes about 3 minutes. With 30 days in the month and a complete mail download every other day your users will pull a total of 71 gigabytes every month from the mailserver. (15 days x 500K x 10,000 users) / 1024 / 1024 Your modems run at 100% utilization, and calls come in evenly spread, day and night. Every user uses exactly the same amount of time online. (I'll omit the calculations but suffice it to say each user can do 72 hours total per month which is more than enough to pull their 7.5MB of mail every month) As a result of the distribution your server will do 2.36 gigs a day in e-mail transfers, (7.5 X 10,000) or about 98MB an hour. A standard 10Mbt card is about 1.25 Megabytes per second, or about 4.5GB an hour, so even a 10Mbt card will be run at less than 1% wire utilization here. Consider that all that mail has to be copied to the server, so the ether is being used twice, and we will make an allowance of 2% That leaves the disk - well all that mail will take up a lot of storage, but the disk won't be accessed all that much, an 80GB IDE should have no trouble with this. CPU utilization is going to be low at that rate too - so a Pentium 166 with an 80GB disk ought to be adequate to cover e-mail for this installation. Considering the hardware you got I think that it's total overkill and a waste of money. Oh well, maybe you can suck up the extra horsepower running a Quake server or something. Anyway, I'll not continue with this because as you should be able to see by now, there is not a single recommendation that we can make that's going to have any meaning whatsover because you have failed to include the relevant information of how much data you really intend on passing from your server. I highly doubt that if you consider yourself small that your passing 2.3 gigs of data a day from your mailserver. If you ask us to speculate then we are going to end up with meaningless and humorous analysis like this one. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Daniel Frazier >Sent: Friday, February 23, 2001 10:01 AM >To: questions@FreeBSD.ORG >Subject: kernel optimizations for an smp mail server... > > >Hey all, > >After using FreeBSD for a few customers colo servers and hearing them >comment on how much they liked it's stability, performance, etc. I've >finally been able to convince the powers that be that FreeBSD >will make a better platform for our mail server. We got a dual PIII >box with a gig of RAM and a RAID 5 array from Penguin Computing and >the first thing we did was install FreeBSD(yay!) > >Now, I've set up plenty of workstations, a few firewalls and web >servers, but never an mail server. We have a fairly small user base, >only about 10,000 users. Can anyone suggest some kernal and/or system >optimizations I should make? I'm sure the main one would be maxusers, >but other than kern.maxproc I'm not sure what else that affects. >Would MAXUSERS = 256 be appropriate? Anything else I need to tweak? >Thanks. > >-- >---------------------------------------------------------------------- >Daniel Frazier <dfrazier@magpage.com> Tel: 302-239-5900 Ext. 231 >Systems Administrator Fax: 302-239-3909 >MAGPAGE, We Power the Internet WWW: http://www.magpage.com/ > >"They that can give up essential liberty to obtain a little temporary >safety deserve neither liberty nor safety." > - Benjamin Franklin, Historical Review of Pennsylvania, 1759. > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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