Category: load-balancing

  • KeepAlived Installation under Debian Etch

    Briefly, KeepAlived is a daemon that is able to provide failover capabilities to servers/services by binding virtual IP addresses to machines. In the event of failure, KeepAlived would reassign this virtual IP to another machine. This action is executed fast (less than 2 seconds) and automatically. This is a very interesting daemon to be used […]

  • Having HAProxy check mysql status through a xinetd script

    HAProxy is able to load balance MySQL wonderfully. The main issue is how to make sure that the backend MySQL server to forward the request to is up and running (I mean not just to establish a connection to port 3306, I mean something more “complete”, that performs a little operation against the MySQL server). […]

  • Sticky sessions (aka persistence)

    While working with load balancers it is sometimes required that the client connects to the same backend server all the time. This concept has several names (e.g.: sticky sessions, session stickiness, persistent sessions, persistence, etc…). Wikipedia explains this concept clearly: One dilemma when operating a load-balanced service, is what to do if the backend servers […]

  • HAProxy hot-reconfiguration

    As of version 1.2.8, a new soft-reconfiguration mechanism has been introduced. It is now possible to “pause” all the proxies by sending a SIGTTOU signal to the processes. This will disable the listening socket without breaking existing connections. After that, sending a SIGTTIN signal to those processes enables the listening sockets again. This is very […]

  • HAProxy installation under Debian Etch (compiling from sources)

    HAProxy is an excellent load balancer which performs extremely well. This page explains how to install HAProxy since this is one of the recommended versions on the ”HAProxy Mailing List”: Server response time discrepancy Also, it has been recommended on that thread to use one of the following kernels: 2.6.22 2.6.25 2.6.18 Installation Steps […]