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[lvs-users] what logic am I missing? cause I don't see any benefits!

To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: [lvs-users] what logic am I missing? cause I don't see any benefits!
From: William Ottley <williamottley@xxxxxxxxx>
Date: Sun, 27 Jun 2010 13:25:31 -0400
Hi all,

I have been working on a test system for a new dot com startup. (one man
show here).
I'm a systems admin, and I've worked on many different types of servers,
network configs, firewalls, etc.

I have been trying to setup a Load Balancing situation, using LVS-DR.
I do have it up and running, and I've used tcpdump to verify where the
requests are going (will provide info below), BUT, I just don't see the
performance!

I have this logical assumption, that i'm hoping is right, but I just can't
seem to figure out why it won't work.
here is the assumption:

I have 3 servers:
LB1, Web1, Web2

I test the latency on both Web1 and Web2 as follows:
Using Jmeter, I connect to each individual Server with: 300 threads, 3 HTTP
Requests, 10 loops.
With both of the web servers, the latency is on average between 250ms and
550ms (up and down cycle)

So, logically speaking this means with these 2 servers, I should be able to
"handle" 600 threads, with 6 HTTP Requests, if I just did a simple round
robin with their IP.
Why? well 300 threads, X 2 servers = 600 threads with the same amount of
latency.

NOW, I point the Jmeter to the VS1 = 192.168.2.100 (outside network), and
set the treads to 600.

In theory, I should get the same amount of latency, which would be between
250ms and 550ms, right?
I don't. I get somewhere from 750ms to 950ms...
This is the exact latency as if I put 600 threads on each individual
webserver...

So what is it i'm missing here???

My network consists as:
(CENTOS 5.4)

LB1:
eth0 - 192.168.2.15
eth1 - 10.10.10.15
lo:100 - 192.168.2.100 (VS1)
net.ipv4.ip_forward = 1
---

WEB1:
eth0 - 192.168.2.5
eth1 - 10.10.10.5  - TCPDUMP confirmed data is coming from 10.10.10.15
lo:100 - 192.168.2.100 (VS1)
net.ipv4.ip_forward = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
---

WEB2:
eth0 - 192.168.2.10 (VS1)
eth1 - 10.10.10.10  - TCPDUMP confirmed data is coming from 10.10.10.15
lo:100 - 192.168.2.100
net.ipv4.ip_forward = 1
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
---

vlan for: 10.10.10.0
vlan for: 192.168.2.0

Any help in this matter would be greatly appreciated.
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