Least Connection problem

Answered Question
Feb 1st, 2009

Dear Sir,

We are using a pair of 11501s to load balance HTTPS traffic to a pair of web servers.

We configure the least connection as the balancing method. But, somehow, web server 1 receive double connections than web server 2.

We suppose the connection to both web servers should be the same.

Any idea?

Thanks.

I have this problem too.
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Correct Answer by Gilles Dufour about 7 years 10 months ago

Because of stickyness !!!

If one server went down or if you started with one server first and then added the other one, the sticky function will force the clients to stick to the same server (the first one) even if this server is overloaded.

This is the purpose of stickyness.

clear the sticky table now that all servers are up and you should get an equal load.

W/ stickyness we can't guarantee that the load will be equal on all the servers.

For example, if you have just 2 machine accessing your VIP.

One machine is sent to Server1 and the other one to server2.

If the first machine opens 10 connections and the 2nd one only 1, you get 10 connections to server 1 and 1 connection to server2.

Totally unequal loadbalancing.

Without stickyness, you would see 5/6 or 6/5.

Gilles.

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Syed Iftekhar Ahmed Sun, 02/01/2009 - 19:51

Are you using any sticky method? If yes then You will not see an equal of connections to all servers when you use any sticky method.

The only connections that are being loadbalanced are connection that do not have an entry in the sticky database, so only new connections are being load balanced.

Syed Iftekhar Ahmed

josephschung Sun, 02/01/2009 - 20:15

Yes, we are using sticky as configured below.

content SSL

vip address 10.106.13.224

redundant-index 36

advanced-balance ssl

application ssl

add service WEBP01

add service WEBP02

protocol tcp

port 443

url "/*"

balance leastconn

active

Both WEB servers are configured identically. Why does WEBP01 always shows 2 or 3 times of opening sessions than WEBP02?

Any idea?

Correct Answer
Gilles Dufour Tue, 02/03/2009 - 02:02

Because of stickyness !!!

If one server went down or if you started with one server first and then added the other one, the sticky function will force the clients to stick to the same server (the first one) even if this server is overloaded.

This is the purpose of stickyness.

clear the sticky table now that all servers are up and you should get an equal load.

W/ stickyness we can't guarantee that the load will be equal on all the servers.

For example, if you have just 2 machine accessing your VIP.

One machine is sent to Server1 and the other one to server2.

If the first machine opens 10 connections and the 2nd one only 1, you get 10 connections to server 1 and 1 connection to server2.

Totally unequal loadbalancing.

Without stickyness, you would see 5/6 or 6/5.

Gilles.

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