Date: Thu, 11 Mar 1999 19:44:22 -0500 From: Mark Mayo <mark@vmunix.com> To: Gary Palmer <gpalmer@FreeBSD.ORG>, freebsd-isp@FreeBSD.ORG Subject: Re: Mail server setup Message-ID: <19990311194422.A4381@vmunix.com> In-Reply-To: <73188.921138367@gjp.erols.com>; from Gary Palmer on Thu, Mar 11, 1999 at 02:46:07AM -0500 References: <73188.921138367@gjp.erols.com>
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On Thu, Mar 11, 1999 at 02:46:07AM -0500, Gary Palmer wrote: > [ delete all trace of previous message so as not to think any one person > is being picked upon ] [SNIP] > Simply put: NFS has its place. Performance-critical systems isn't one of the > areas NFS is suited for. Not unless you want to throw a lot more hardware at > the problem than you really need to. NFS gets you one thing that locally attached disk can't - multiple front-end hosts can see the same set of data. For setups with several hosts handling the mail, it is trivial to build a SMTP/POP proxy to route people to the correct mail server based on username (I know, I've done it..). That gets you nice horizontal scaling to infinity pretty much, but doesn't help you out in terms of availability or serviceability. How do you do an OS upgrade on a front end host with no cx impact? What happens if a host goes down? What happens if your disk array goes tits up? I'm not saying I like NFS.. but when done correctly (use a real RDBMS for most of the POP stuff to eliminate trips to the NFS server for mail checks, avoid locking over NFS, failover NFS servers listed for clients, etc.) you can build a decent NFS based solution that scales and is very tolerant to host / filer crashes. I'd do it with local disk if I could, but I haven't been able to come up with a solution based on local disk that I'm satisfied with.. At any rate, building large email solutions is a neat challenge, and I'm not sure NFS or local disk has clear advantages. In the past, I've leaned towards local disk, but now I'm swinging over to the NFS camp.. 8) Of course, that probably has just as much to do with my hatred of Sun's ludicrously priced A5000 disk arrays I'm using right now as it does with anything else.. ;) That and the fact that I'm happy as pie with my NetApp F760 test units, and F740 production filers.. > Yes, this is verging on a religious argument. However, the fact that even Sun > now says that NFS mounted /var/mail spools is a bad idea speaks volumes. Interesting how Sun started making such statements shortly after they started pushing SIMS - which doesn't run over NFS reliably. Coincidence? :-) -Mark > > Gary > -- > Gary Palmer FreeBSD Core Team Member > FreeBSD: Turning PC's into workstations. See http://www.FreeBSD.ORG/ for info > -- ------------------------------------------------------------------------ Mark Mayo mark@vmunix.com RingZero Comp. http://www.vmunix.com/mark ------------------------------------------------------------------------ "The human brain is like an enormous fish - it is flat and slimy and has gills through which it can see." -- Monty Python To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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