While Red Hat Enterprise Linux can be configured in a variety of different ways, the
configurations can be broken into two major categories:
This part explains what a load-balancing cluster system is and how
to configure a load-balancing system using Linux Virtual
Servers on Red Hat Enterprise Linux.
To an outside user accessing a hosted service (such as a website or
database application), a Linux Virtual Server (LVS) cluster appears as
one server. In reality, however, the user is actually accessing a
cluster of two or more servers behind a pair of redundant LVS routers
that distribute client requests evenly throughout the cluster
system. Load-balanced clustered services allow administrators to use
commodity hardware and Red Hat Enterprise Linux to create continuous and consistent
access to all hosted services while also addressing availability
An LVS cluster consists of at least two layers. The first layer is
composed of a pair of similarly configured Linux machines or
cluster members. One of these machine acts as
the LVS routers, configured to direct requests
from the Internet to the cluster. The second layer consists of a
cluster of machines called real servers. The
real servers provide the critical services to the end-user while the
LVS router balances the load on these servers.
For a detailed overview of LVS clustering, refer to Chapter 7 Linux Virtual Server Overview.