Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER... Installation guide

Red Hat Enterprise Linux 5
Cluster Suite Overview
Red Hat Cluster Suite for Red Hat Enterprise Linux 5

Cluster Suite Overview
Red Hat Enterprise Linux 5 Cluster Suite Overview
Red Hat Cluster Suite for Red Hat Enterprise Linux 5
Edition 4
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Red Hat Cluster Suite Overviewprovides an overview of Red Hat Cluster Suite for Red Hat Enterprise
Linux 5.

iii
Introduction v
1. Document Conventions ................................................................................................... vi
1.1. Typographic Conventions ..................................................................................... vi
1.2. Pull-quote Conventions ........................................................................................ vii
1.3. Notes and Warnings ........................................................................................... viii
2. Feedback ..................................................................................................................... viii
1. Red Hat Cluster Suite Overview 1
1.1. Cluster Basics .............................................................................................................. 1
1.2. Red Hat Cluster Suite Introduction ................................................................................ 2
1.3. Cluster Infrastructure .................................................................................................... 3
1.3.1. Cluster Management .......................................................................................... 4
1.3.2. Lock Management ............................................................................................. 5
1.3.3. Fencing ............................................................................................................. 5
1.3.4. Cluster Configuration System ............................................................................. 9
1.4. High-availability Service Management .......................................................................... 11
1.5. Red Hat GFS ............................................................................................................. 14
1.6. Cluster Logical Volume Manager ................................................................................. 15
1.7. Global Network Block Device ...................................................................................... 19
1.8. Linux Virtual Server .................................................................................................... 20
1.8.1. Two-Tier LVS Topology ................................................................................... 22
1.8.2. Three-Tier LVS Topology ................................................................................. 24
1.8.3. Routing Methods ............................................................................................. 25
1.8.4. Persistence and Firewall Marks ........................................................................ 28
1.9. Cluster Administration Tools ........................................................................................ 29
1.9.1. Conga ............................................................................................................. 29
1.9.2. Cluster Administration GUI ............................................................................... 32
1.9.3. Command Line Administration Tools ................................................................. 35
1.10. Linux Virtual Server Administration GUI ..................................................................... 36
1.10.1. CONTROL/MONITORING .............................................................................. 37
1.10.2. GLOBAL SETTINGS ..................................................................................... 38
1.10.3. REDUNDANCY ............................................................................................. 40
1.10.4. VIRTUAL SERVERS ...................................................................................... 41
2. Red Hat Cluster Suite Component Summary 49
2.1. Cluster Components ................................................................................................... 49
2.2. Man Pages ................................................................................................................ 53
2.3. Compatible Hardware ................................................................................................. 56
A. Revision History 57
Index 59

iv

v
Introduction
This document provides a high-level overview of Red Hat Cluster Suite for Red Hat Enterprise Linux 5
and is is organized as follows:
•Chapter 1, Red Hat Cluster Suite Overview
•Chapter 2, Red Hat Cluster Suite Component Summary
Although the information in this document is an overview, you should have advanced working
knowledge of Red Hat Enterprise Linux and understand the concepts of server computing to gain a
good comprehension of the information.
For more information about using Red Hat Enterprise Linux, refer to the following resources:
•Red Hat Enterprise Linux Installation Guide — Provides information regarding installation of Red
Hat Enterprise Linux 5.
•Red Hat Enterprise Linux Deployment Guide — Provides information regarding the deployment,
configuration and administration of Red Hat Enterprise Linux 5.
For more information about Red Hat Cluster Suite for Red Hat Enterprise Linux 5, refer to the following
resources:
•Configuring and Managing a Red Hat Cluster — Provides information about installing, configuring
and managing Red Hat Cluster components.
•Logical Volume Manager 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).
•Global File System 2: Configuration and Administration — Provides information about installing,
configuring, and maintaining Red Hat GFS2 (Red Hat Global File System 2).
•Using Device-Mapper Multipath — Provides information about using the Device-Mapper Multipath
feature of Red Hat Enterprise Linux 5.
•Using GNBD with Global File System — Provides an overview on using Global Network Block
Device (GNBD) with Red Hat GFS.
•Linux Virtual Server Administration — Provides information on configuring high-performance
systems and services with the Linux Virtual Server (LVS).
•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/.

Introduction
vi
1. Document Conventions
This manual uses several conventions to highlight certain words and phrases and draw attention to
specific pieces of information.
In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts1 set. The
Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not,
alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later includes
the Liberation Fonts set by default.
1.1. Typographic Conventions
Four typographic conventions are used to call attention to specific words and phrases. These
conventions, and the circumstances they apply to, are as follows.
Mono-spaced Bold
Used to highlight system input, including shell commands, file names and paths. Also used to highlight
keycaps and key combinations. For example:
To see the contents of the file my_next_bestselling_novel in your current
working directory, enter the cat my_next_bestselling_novel command at the
shell prompt and press Enter to execute the command.
The above includes a file name, a shell command and a keycap, all presented in mono-spaced bold
and all distinguishable thanks to context.
Key combinations can be distinguished from keycaps by the hyphen connecting each part of a key
combination. For example:
Press Enter to execute the command.
Press Ctrl+Alt+F1 to switch to the first virtual terminal. Press Ctrl+Alt+F7 to
return to your X-Windows session.
The first paragraph highlights the particular keycap to press. The second highlights two key
combinations (each a set of three keycaps with each set pressed simultaneously).
If source code is discussed, class names, methods, functions, variable names and returned values
mentioned within a paragraph will be presented as above, in mono-spaced bold. For example:
File-related classes include filesystem for file systems, file for files, and dir for
directories. Each class has its own associated set of permissions.
Proportional Bold
This denotes words or phrases encountered on a system, including application names; dialog box text;
labeled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example:
Choose System → Preferences → Mouse from the main menu bar to launch Mouse
Preferences. In the Buttons tab, click the Left-handed mouse check box and click
Close to switch the primary mouse button from the left to the right (making the mouse
suitable for use in the left hand).
1 https://fedorahosted.org/liberation-fonts/

Pull-quote Conventions
vii
To insert a special character into a gedit file, choose Applications → Accessories
→ Character Map from the main menu bar. Next, choose Search → Find… from
the Character Map menu bar, type the name of the character in the Search field
and click Next. The character you sought will be highlighted in the Character Table.
Double-click this highlighted character to place it in the Text to copy field and then
click the Copy button. Now switch back to your document and choose Edit → Paste
from the gedit menu bar.
The above text includes application names; system-wide menu names and items; application-specific
menu names; and buttons and text found within a GUI interface, all presented in proportional bold and
all distinguishable by context.
Mono-spaced Bold Italic or Proportional Bold Italic
Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or
variable text. Italics denotes text you do not input literally or displayed text that changes depending on
circumstance. For example:
To connect to a remote machine using ssh, type ssh [e-mail] at
a shell prompt. If the remote machine is example.com and your username on that
machine is john, type ssh [email protected].
The mount -o remount file-system command remounts the named file
system. For example, to remount the /home file system, the command is mount -o
remount /home.
To see the version of a currently installed package, use the rpm -q package
command. It will return a result as follows: package-version-release.
Note the words in bold italics above — username, domain.name, file-system, package, version and
release. Each word is a placeholder, either for text you enter when issuing a command or for text
displayed by the system.
Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and
important term. For example:
Publican is a DocBook publishing system.
1.2. Pull-quote Conventions
Terminal output and source code listings are set off visually from the surrounding text.
Output sent to a terminal is set in mono-spaced roman and presented thus:
books Desktop documentation drafts mss photos stuff svn
books_tests Desktop1 downloads images notes scripts svgs
Source-code listings are also set in mono-spaced roman but add syntax highlighting as follows:
package org.jboss.book.jca.ex1;
import javax.naming.InitialContext;
public class ExClient
{

Introduction
viii
public static void main(String args[])
throws Exception
{
InitialContext iniCtx = new InitialContext();
Object ref = iniCtx.lookup("EchoBean");
EchoHome home = (EchoHome) ref;
Echo echo = home.create();
System.out.println("Created Echo");
System.out.println("Echo.echo('Hello') = " + echo.echo("Hello"));
}
}
1.3. Notes and Warnings
Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.
Note
Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note
should have no negative consequences, but you might miss out on a trick that makes your
life easier.
Important
Important boxes detail things that are easily missed: configuration changes that only
apply to the current session, or services that need restarting before an update will apply.
Ignoring a box labeled 'Important' won't cause data loss but may cause irritation and
frustration.
Warning
Warnings should not be ignored. Ignoring warnings will most likely cause data loss.
2. Feedback
If you spot a typo, or if you have thought of a way to make this document better, we would love to
hear from you. Please submit a report in Bugzilla (http://bugzilla.redhat.com/bugzilla/) against the
component Documentation-cluster.
Be sure to mention the document's identifier:
Cluster_Suite_Overview(EN)-5 (2010-02-05T09:51)
By mentioning this document's identifier, we know exactly which version of the guide you have.
If you have a suggestion for improving the documentation, try to be as specific as possible. If you have
found an error, please include the section number and some of the surrounding text so we can find it
easily.

Chapter 1.
1
Red Hat Cluster Suite Overview
Clustered systems provide reliability, scalability, and availability to critical production services. Using
Red Hat Cluster Suite, you can create a cluster to suit your needs for performance, high availability,
load balancing, scalability, file sharing, and economy. This chapter provides an overview of Red Hat
Cluster Suite components and functions, and consists of the following sections:
•Section 1.1, “Cluster Basics”
•Section 1.2, “Red Hat Cluster Suite Introduction”
•Section 1.3, “Cluster Infrastructure”
•Section 1.4, “High-availability Service Management”
•Section 1.5, “Red Hat GFS”
•Section 1.6, “Cluster Logical Volume Manager”
•Section 1.7, “Global Network Block Device”
•Section 1.8, “Linux Virtual Server”
•Section 1.9, “Cluster Administration Tools”
•Section 1.10, “Linux Virtual Server Administration GUI”
1.1. Cluster Basics
A cluster is two or more computers (called nodes or members) that work together to perform a task.
There are four major types of clusters:
• Storage
• High availability
• Load balancing
• High performance
Storage clusters provide a consistent file system image across servers in a cluster, allowing the
servers to simultaneously read and write to a single shared file system. A storage cluster simplifies
storage administration by limiting the installation and patching of applications to one file system.
Also, with a cluster-wide file system, a storage cluster eliminates the need for redundant copies of
application data and simplifies backup and disaster recovery. Red Hat Cluster Suite provides storage
clustering through Red Hat GFS.
High-availability clusters provide continuous availability of services by eliminating single points
of failure and by failing over services from one cluster node to another in case a node becomes
inoperative. Typically, services in a high-availability cluster read and write data (via read-write
mounted file systems). Therefore, a high-availability cluster must maintain data integrity as one cluster
node takes over control of a service from another cluster node. Node failures in a high-availability
cluster are not visible from clients outside the cluster. (High-availability clusters are sometimes
referred to as failover clusters.) Red Hat Cluster Suite provides high-availability clustering through its
High-availability Service Management component.

Chapter 1. Red Hat Cluster Suite Overview
2
Load-balancing clusters dispatch network service requests to multiple cluster nodes to balance the
request load among the cluster nodes. Load balancing provides cost-effective scalability because you
can match the number of nodes according to load requirements. If a node in a load-balancing cluster
becomes inoperative, the load-balancing software detects the failure and redirects requests to other
cluster nodes. Node failures in a load-balancing cluster are not visible from clients outside the cluster.
Red Hat Cluster Suite provides load-balancing through LVS (Linux Virtual Server).
High-performance clusters use cluster nodes to perform concurrent calculations. A high-performance
cluster allows applications to work in parallel, therefore enhancing the performance of the applications.
(High performance clusters are also referred to as computational clusters or grid computing.)
Note
The cluster types summarized in the preceding text reflect basic configurations; your
needs might require a combination of the clusters described.
1.2. Red Hat Cluster Suite Introduction
Red Hat Cluster Suite (RHCS) is an integrated set of software components that can be deployed
in a variety of configurations to suit your needs for performance, high-availability, load balancing,
scalability, file sharing, and economy.
RHCS consists of the following major components (refer to Figure 1.1, “Red Hat Cluster Suite
Introduction”):
• Cluster infrastructure — Provides fundamental functions for nodes to work together as a cluster:
configuration-file management, membership management, lock management, and fencing.
• High-availability Service Management — Provides failover of services from one cluster node to
another in case a node becomes inoperative.
• Cluster administration tools — Configuration and management tools for setting up, configuring, and
managing a Red Hat cluster. The tools are for use with the Cluster Infrastructure components, the
High-availability and Service Management components, and storage.
• Linux Virtual Server (LVS) — Routing software that provides IP-Load-balancing. LVS runs in a pair
of redundant servers that distributes client requests evenly to real servers that are behind the LVS
servers.
You can supplement Red Hat Cluster Suite with the following components, which are part of an
optional package (and not part of Red Hat Cluster Suite):
• GFS (Global File System) and GFS2 (Global File System 2) — Provides a cluster file system for use
with Red Hat Cluster Suite. GFS/GFS2 allows multiple nodes to share storage at a block level as if
the storage were connected locally to each cluster node.
• Cluster Logical Volume Manager (CLVM) — Provides volume management of cluster storage.