Chapter 6. Introduction to Linux Virtual Server
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 interruption.
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 cluster
Guides you through the Piranha Configuration Tool, a
graphical interface used for configuring and monitoring an LVS
Red Hat Enterprise Linux implements highly available server solutions via clustering. It is
important to note that cluster computing consists
of three distinct branches:
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 servers.
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
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.