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Re: DR or NAT

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: DR or NAT
From: Bruce Richardson <itsbruce@xxxxxxxxxxx>
Date: Thu, 28 Apr 2005 16:09:38 +0100
On Thu, Apr 28, 2005 at 04:26:50PM +0200, orpheus@xxxxxxxxxxxxxxxxxxxx wrote:
> On Thursday 28 April 2005 15:43, Bruce Richardson wrote:
> > The advantages of NAT are that it doesn't require any special settings
> > (e.g. arp suppression on the application servers),

Erm, I should have said "it doesn't require any special settings ( yada
yada ) on the application servers".  Misleading punctuation, there.

> first, thanks for answer
> do you have some recommendations on hardware used for that?
> I think 2 eth cards are real minimum for that, but would it help to have 3 or 
> 4 ?

If you are doing HA, do it properly.  Use bonded interfaces where ever
possible.  For the directors you want a bonded pair for the external
interface, for the internal interface and for the hearbeat interface (be
careful to test that one, though).  That means six network ports, which
is easily achievable even with a 1U rackserver if you get one with two
on-board NICs and add either two dual-port cards or one quad-port card.

The nice thing about the bonded interfaces is that you can configure
them to provide fault tolerance (suriving the failure of one link) or
load-balancing (keeps your throughput at a high level) or both of those
at once or even port aggregation (treat 2 cards with X bandwidth as one
card with 2X bandwidth, significantly raising your maximum throughput).
Some of those options require the director to be connected to a smart
switch, though.

> How it is with CPU and memory. Right now it is PIII 700MHz 
> (735.315MHz :) ) with 512MB of memory with one eth card.

When you are trying to maximise network throughput, CPU speed is much
more important than RAM.  You need to get your calculator out and work
out how much traffic each individual application server is likely to see
and then compare the likely peak combined traffic with the maximum that
the director can handle (both in terms of NIC bandwidth and CPU speed).

-- 
Bruce

It is impolite to tell a man who is carrying you on his shoulders that
his head smells.

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