Date: Sun, 05 Nov 2000 14:30:09 -0700 From: Chris Fedde <chris@fedde.littleton.co.us> To: Len Conrad <lconrad@Go2France.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: where to increase number of files Message-ID: <200011052130.eA5LU9x15228@fedde.littleton.co.us> In-Reply-To: <5.0.0.25.0.20001105185632.00ad8680@mail.Go2France.com>
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On Sun, 05 Nov 2000 19:05:04 +0100 Len Conrad wrote:
+------------------
| I've got a client with largish FreeBSD/posfif mailhub (200K
| mgs/weekday) that is hitting the 1024 open files limit.
+------------------
I've done a few wag calculations on this volume. Assuming that
your client's site is like most others, 80% of the messages transit
in 20% of the time. so 160K messages will transit the hub in 4.8
hours or about 9/second.
If I assume that very connection takes three file descriptors
(remote connection, queue file, and log) then the 1024 above
represents something like 340 actual concurrent connections.
Plugging that through Littles law gives an average hold time at
peak of around 35 seconds. This seems like a long average hold
time for mail transits. In my experiance with sendmail times beyond
5 seconds are the exception rather than the rule.
Other things that factor into long hold times are identd queries
and long DNS lookups. You can probably turn off identd queries.
DNS tends to be a bit harder to speed up.
Managing resource consumption is probably a good idea too.
I don't have any experiance with postfix. Is there a connection
rate throttle that can be turned on? Or a peak connection count?
BTW /etc/rc makes reference to /etc/rc.sysctl. I might consider
creating it and putting your commands there.
chris
--
Chris Fedde
303 773 9134
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