Hi Chris,

I'm not a network specialist but when we pointed directly to OpenLDAP server we could see a much less ACKs on the dump than when pointed to load balance VIP. Maybe you could do this test on your environment and check the results.

We created a Java Class to perform some tests on our tree and tcpdump was used to see the differences between the queries directly on the server and through the F5. The tcpdump file was 1MB larger when pointed to F5 using the same search algorithm of our Java Class.

This is interesting because we also have a lot of GNU/Linux servers which peform user, password and group validation against OpenLDAP through the F5 and for that end the Nagle's Algorithm still active but there is no performance loss. I think this is related and only applies to some kind of applications which really need real time response from LDAP [1].

[1] - http://en.wikipedia.org/wiki/Nagle%27s_algorithm#Interactions_with_real-time_systems

Thanks,

Matheus Morais

On Tue, Aug 24, 2010 at 3:39 PM, Chris Jacobs <Chris.Jacobs@apollogrp.edu> wrote:

Matheus,

 

What was generating the ‘too many ACKs’?

 

We’re also using F5’s in all locations (in front of mirrored masters, and 3 sets of load balanced slaves) – and have only had an issue in one location which was related to an overloaded VM cluster. 

 

Thanks,

- chris

 

From: openldap-technical-bounces@OpenLDAP.org [mailto:openldap-technical-bounces@OpenLDAP.org] On Behalf Of Matheus Morais
Sent: Tuesday, August 24, 2010 11:31 AM
To: openldap-technical@openldap.org
Subject: OpenLDAP and Load Balance F5 issue

 

Hi there,

We were having some performance troubles using OpenLDAP and F5 load balance solution from BigIP at a high concurrent enviroment. We faced the problem for one month after I discovered that those problems didn't happen when applications was pointed directly to OpenLDAP server instead of load balance VIP. After a tcpdump analysis of the packages we realize that are too many ACK comming from each request.

Last week we solved the problem unsetting Nagle's algorithm on the load balance virtual server which was causing this issue.

So, if you look yourself on a similiar situation, please check the Nagle's algorithm on the F5 configuration!

Thanks,

Matheus Morais


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