2.1. Load-Balancing Clusters Using Linux Virtual Servers
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 requirements.
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 1, Linux Virtual Server Overview.
For more information about Red Hat Enterprise Linux 4.5, refer to the following resources:
Red Hat Enterprise Linux Installation Guide — Provides information regarding installation.
Red Hat Enterprise Linux Introduction to System Administration — Provides introductory information for new Red Hat Enterprise Linux system administrators.
Red Hat Enterprise Linux System Administration Guide — Provides more detailed information about configuring Red Hat Enterprise Linux to suit your particular needs as a user.
Red Hat Enterprise Linux Reference Guide — Provides detailed information suited for more experienced users to reference when needed, as opposed to step-by-step instructions.
Red Hat Enterprise Linux Security Guide — Details the planning and the tools involved in creating a secured computing environment for the data center, workplace, and home.
For more information about Red Hat Cluster Suite for Red Hat Enterprise Linux 4.5, refer to the following resources:
Red Hat Cluster Suite Overview — Provides a high level overview of the Red Hat Cluster Suite.
Configuring and Managing a Red Hat Cluster — Provides information about installing, configuring and managing Red Hat Cluster components.
LVM Administrator's Guide: Configuration and Administration — Provides a description of the Logical Volume Manager (LVM), including information on running LVM in a clustered environment.
Global File System: Configuration and Administration — Provides information about installing, configuring, and maintaining Red Hat GFS (Red Hat Global File System).
Using GNBD with Global File System — Provides an overview on using Global Network Block Device (GNBD) with Red Hat GFS.
Red Hat Cluster Suite Release Notes — Provides information about the current release of Red Hat Cluster Suite.
Red Hat Cluster Suite documentation and other Red Hat documents are available in HTML, PDF, and RPM versions on the Red Hat Enterprise Linux Documentation CD and online at http://www.redhat.com/docs/.