Date: Wed, 20 Jun 2001 22:14:09 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: void <float@firedrake.org> Cc: Matt Dillon <dillon@earth.backplane.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: max kernel memory Message-ID: <3B3182A1.3FA92488@mindspring.com> References: <Pine.LNX.4.21.0106201112090.1235-100000@vangogh.indranetworks.com> <200106200704.f5K74M706441@earth.backplane.com> <20010620193151.C2973@firedrake.org>
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void wrote: > > On Wed, Jun 20, 2001 at 12:04:22AM -0700, Matt Dillon wrote: > > > > A web proxy could be > > round-robined fairly easily, but for a mail relay it > > is often a good idea to split the incoming and outgoing > > mail into two separate round robins (two separate groups > > of machines). > > Why's that? So you can tune each type of machine appropriately for > the task? How would you tune incoming and outgoing mail servers > differently? Outgoing mail servers and incoming mail servers have different load characteristics and requirements. Without giving away any intellectual property from my own startup, here's a small sample: o Incoming SPAM filtering +'ed address delivery Virtual domains Automated "spam" complaint handling Automated "abuse" complaint handling Virus scanning Relay denial Per domain mail queues o Outgoing Relay permitted for customers SMTP-after-POP SMTP AUTH Exponential rate limiting, to avoid being a SPAM source Per message recipient count limiting "" Total message count limiting Outbound queue aging Identd processing, to avoid 3 minute delays DNS outage handling/avoidance Queue aging Queue division Large queue processing Hosted mailing list processing Connection caching That's about 1/3 my list for each of the two roles I've chosen to disclose here. In other words, it's a pretty big list, with a lot of differences between the roles, translating into a lot of differences between the tuning of both the applications you run, and the servers themselves (you might even decide to run sendmail in one direction, and qmail in the other, based on operational characteristics). FWIW: I designed and implemented (with help) the IBM Web Connections NOC in Rochester New York, for pretty much everything except the autoconfiguration database for a specialized appliance. Matt was one of the founders of Best Internet, Inc., which was bought out by Verio. Knowing how this stuff works is why Matt and I and others were so offended at the "SysAdmin Magazine ``benchmark'' report on FreeBSD vs. other OSs": it was not, as some have claimed, "sour grapes", it was professional indignation. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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