Chapter 6. Introduction to Linux
Using Red Hat Enterprise Linux, it is possible to create highly
available server clustering solutions able to withstand many common
hardware and software failures with little or no interruption of
critical services. By allowing multiple computers to work together
in offering these critical services, system administrators can plan
and execute system maintenance and upgrades without service
The chapters in this part guide you through the following steps
in understanding and deploying a clustering solution based on the
Red Hat Enterprise Linux Linux Virtual
Server (LVS) technology:
Explains the Linux Virtual Server technology used by Red Hat
Enterprise Linux to create a load-balancing cluster
Explains how to configure a Red Hat Enterprise Linux LVS
Guides you through the Piranha
Configuration Tool, a graphical interface used for configuring
and monitoring an LVS cluster
Red Hat Enterprise Linux implements highly available server
solutions via clustering. It is important to note that cluster computing consists of three distinct
Compute clustering (such as Beowulf)
uses multiple machines to provide greater computing power for
computationally intensive tasks. This type of clustering is not
addressed by Red Hat Enterprise Linux.
High-availability (HA) clustering uses
multiple machines to add an extra level of reliability for a
service or group of services.
Load-balance clustering uses
specialized routing techniques to dispatch traffic to a pool of
Red Hat Enterprise Linux addresses the latter two types of
clustering technology. Using a collection of programs to monitor
the health of the systems and services in the cluster.
The clustering technology included in Red Hat Enterprise Linux
is not synonymous with fault tolerance.
Fault tolerant systems use highly specialized and often very
expensive hardware to implement a fully redundant environment in
which services can run uninterrupted by hardware failures.
However, fault tolerant systems do not account for operator and
software errors which Red Hat Enterprise Linux can address through
service redundancy. Also, since Red Hat Enterprise Linux is
designed to run on commodity hardware, it creates an environment
with a high level of system availability at a fraction of the cost
of fault tolerant hardware.