Re: [LARTC] Hardware Configuration Ideas

From: Grant Taylor <gtaylor@riverviewtech.net>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Hardware Configuration Ideas
Date: Wed, 17 Aug 2005 06:20:32 +0000	[thread overview]
Message-ID: <4302D730.3090105@riverviewtech.net> (raw)
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> You don't. Maybe that's conntrack's default, but you can set it to a higher
> number manually. The required memory is approx 400b per connection (depends on
> iptables/kernel compile time options). The rather conservative default (hashsize
> = 1/16384th of RAM) is for a generic system. For more info look at
> ip_conntrack_core.c
> 
> 65535 connections need about 25MB in RAM, so before starting iptables, do
> modprobe ip_conntrack hashsize92
> (contrack_max is auto-set to 8*hashsize, this is the recommended relation). In
> fact my distro Shurdix automatically sets up larger hashsize than the default,
> depending on system memory.

Hmm, I did not have much time to solve this problem at the time and documentation was hard to come by at the time and what I did find was old.  Alass I was not subscribed to this list to ask for help either.  Note things have changed sense then.  :)

> While a redundant system is indeed a good idea, I recommend making sure the
> router is rock stable. This doesn't necessarily require high-end / fast
> hardware, it is recommended to stress test it before going live
> (memtest/cpuburn/whatever).
> 
> My tip is not to use "primitive" network cards like those based on rtl8139 which
> you require high bandwidth. This has the most noticeable impact on performance.
> I have ok experience with 3com's, I've heard intels are even better.

I would agree to both points.  I have had good luck with the rtl8139s on Cable / DSL and T1 routers but I would want something better (3C905x cards) for a much higher bandwidth installation.  The redundant (identical) system is for those cases where the cleaning crew and / or momma nature and / or Mr Murphy have their way with your box.  We have all had it happen (or will) in some way or another at some time.  It is not "if" a box will fail in some way, but rather "when".  The failure may not be any thing you could prevent.  I think the stores in Florida this year are a good example of that.

Grant. . . .
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