[34214] in North American Network Operators' Group
Re: Scalable Mail solution with NAS
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Wed Jan 31 10:36:19 2001
Message-Id: <200101311533.f0VFXZP2068114@black-ice.cc.vt.edu>
To: chrisb@kippona.com
Cc: nanog@merit.edu
In-Reply-To: Your message of "Wed, 31 Jan 2001 10:13:40 EST."
<20010131101340M.chrisb@kippona.com>
From: Valdis.Kletnieks@vt.edu
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Date: Wed, 31 Jan 2001 10:33:35 -0500
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On Wed, 31 Jan 2001 10:13:40 EST, chrisb@kippona.com said:
> Is the number of mailboxes the key metric? What breaks sendmail + "a
> very big disk"? Isn't it the traffic?
The two biggest problems with very-high-volume servers and sendmail are:
1) You *really* need to use multiple queues and some sort of aging scheme,
so mail backlogged for dead hosts gets out of your main queue. If a queue
gets too full, Sendmail exhibits bad O(N**2) behavior in sorting/running
the queue.
2) If you are serving mailboxes (as opposed to a Listserv-type machine where
the mail *leaves*), what can kill you isn't the sendmail, but the local
delivery program and POP/IMAP checks. You get enough bozo users who have
set Eudora to check for new mail every 2 minutes, you'll get bogged down
no matter HOW fast Sendmail itself is.
--
Valdis Kletnieks
Operating Systems Analyst
Virginia Tech
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