[ Thanks to Falko
Timme for this link. ]
“This article explains how to set up a two-node load balancer in
an active/passive configuration with HAProxy and keepalived on
Debian Etch. The load balancer sits between the user and two (or
more) backend Apache web servers that hold the same content. Not
only does the load balancer distribute the requests to the two
backend Apache servers, it also checks the health of the backend
servers. If one of them is down, all requests will automatically be
redirected to the remaining backend server. In addition to that,
the two load balancer nodes monitor each other using keepalived,
and if the master fails, the slave becomes the master, which means
the users will not notice any disruption of the service. HAProxy is
session-aware, which means you can use it with any web application
that makes use of sessions (such as forums, shopping carts,
etc.)…”