MACROMEDIA COLDFUSION MX-CLUSTERCATS Mounting instructions

macromedia®
Using ClusterCATS

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Part Number ZCL2M100
Acknowledgments
Project Management: Stephen M. Gilson
Writing: Stephen M. GIlson
Editing: Linda Adler and Noreen Maher
First Edition: May 2002
Macromedia, Inc.
600 Townsend St.
San Francisco, CA 94103

CONTENTS
ABOUT THIS BOOK . . . . . . . . . . . . . . . . . . . . . . . . . . . VII
Developer resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
About Macromedia documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Viewing online documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Contacting Macromedia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x
CHAPTER 1 Before You Begin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
ClusterCATS overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
ClusterCATS capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Detailed overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
ClusterCATS product configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
ClusterCATS components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
ClusterCATS Server system requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
ClusterCATS Explorer and Web Explorer system requirements . . . . . . . . . . . . . . . . . . . . .8
CHAPTER 2 Scalability and Availability Overview. . . . . . . . . . . . . . 9
What is scalability?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Load management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Successful scalability implementations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Designing and coding scalable applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Avoiding common bottlenecks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
DNS effects on website performance and availability . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Load testing your web applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
What is website availability?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Availability and reliability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Common failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Website availability scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Failover considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Creating scalable and highly available sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
What is clustering? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Hardware-based clustering solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Software-based clustering solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Combining hardware and software clustering solutions . . . . . . . . . . . . . . . . . . . . . . . . . .32

iv Contents
CHAPTER 3 Installing ClusterCATS . . . . . . . . . . . . . . . . . . . . . . . . 33
Before you install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Upgrading from a previous version of ClusterCATS. . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Configuring DNS servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Configuring server failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Using ClusterCATS dynamic IP addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Configuring firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Analyzing web server content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Considering domain controllers (Windows NT only). . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Installing ClusterCATS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Installing ClusterCATS on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Installing ClusterCATS on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
After you install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
CHAPTER 4 Configuring Clusters . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Introduction to ClusterCATS Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
ClusterCATS Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
ClusterCATS Explorer (Windows only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
ClusterCATS Web Explorer (UNIX only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
ClusterCATS Server Administrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
btadmin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Creating clusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Creating clusters in Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Creating clusters in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Removing clusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
Adding cluster members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Adding cluster members in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
Adding cluster members in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
Removing cluster members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Removing cluster members in Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Removing cluster members in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Server load thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Configuring load thresholds in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Configuring load thresholds on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Session-aware load balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Enabling session-aware load balancing on Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Enabling session-aware load balancing on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Persistent session failover in JRun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
Session swapping overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
Configuring JRun for session swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
Configuring ClusterCATS for session swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
Using shared files for session swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
Using JDBC for session swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
Using ColdFusion probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
Configuring ColdFusion probes in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
Configuring ColdFusion probes in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
Using JRun probes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84
Configuring JRun probes in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84
Configuring JRun probes in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

C o n t e n t s v
Load-balancing devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Using Cisco LocalDirector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
Using third-party load-balancing devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95
Administrator alarm notifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
Configuring administrator alarm notifications on Windows. . . . . . . . . . . . . . . . . . . . . . .98
Configuring administrator alarm notifications on UNIX . . . . . . . . . . . . . . . . . . . . . . . . .99
Administrator e-mail options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
Configuring administration e-mail options on Windows . . . . . . . . . . . . . . . . . . . . . . . .100
Configuring administration e-mail options on UNIX. . . . . . . . . . . . . . . . . . . . . . . . . . .101
Administering security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Configuring authentication on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Configuring authentication on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
CHAPTER 5 Maintaining Cluster Members. . . . . . . . . . . . . . . . . . 109
Understanding ClusterCATS server modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110
Changing active/passive settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
Changing active/passive settings in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
Changing active/passive settings in UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112
Changing restricted/unrestricted settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113
Restricting/unrestricting servers in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113
Restricting/unrestricting servers in UNIX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114
Using maintenance mode (Windows only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
Updating a cluster member (Windows only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118
Resetting cluster members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120
Resetting cluster members on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120
Resetting cluster members on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120
CHAPTER 6 ClusterCATS Utilities . . . . . . . . . . . . . . . . . . . . . . . . . .121
Using btadmin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Using btadmin on Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Using btadmin on UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Using bt-start-server and bt-stop-server (UNIX only) . . . . . . . . . . . . . . . . . . . . . . . . . . . .125
Using btcfgchk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
Sample output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
btcfgchk DNS errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126
Using hostinfo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Sample output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
Using sniff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130
Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130
Sample output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130

vi Contents
CHAPTER 7 Optimizing ClusterCATS . . . . . . . . . . . . . . . . . . . . . . .131
ClusterCATS dynamic IP addressing (Windows only) . . . . . . . . . . . . . . . . . . . . . . . . . . . .132
Understanding static and dynamic IP address configurations . . . . . . . . . . . . . . . . . . . . .132
Benefits of ClusterCATS dynamic IP addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Setting up maintenance IP addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133
Enabling ClusterCATS dynamic IP addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135
Using server failover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
Static versus ClusterCATS dynamic IP addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
Windows domain controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
Configuring load-balancing metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138
Overview of metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138
Load types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Output variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Troubleshooting the load-balancing metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

vii
ABOUT THIS BOOK
Using ClusterCATS describes how to use ClusterCATS, the clustering technology that
provides load-balancing and failover services to assure high availability for your web
servers.
Contents
•Developer resources .............................................................................................. viii
•About Macromedia documentation ........................................................................ ix
•Contacting Macromedia.......................................................................................... x

viii About This Book
Developer resources
Macromedia, Inc. is committed to setting the standard for customer support in developer
education, documentation, technical support, and professional services. The
Macromedia website is designed to give you quick access to the entire range of online
resources. The following table shows the locations of these resources.
Resource Description URL
Macromedia
website
General information about Macromedia
products and services
http://www.macromedia.com
Information on
ColdFusion
Detailed product information on
ColdFusion and related topics
http://www.macromedia.com/coldfusion
Macromedia
ColdFusion
Support Center
Professional support programs that
Macromedia offers
http://www.macromedia.com/support/
coldfusion
ColdFusion
Online Forums
Access to experienced ColdFusion
developers through participation in the
Online Forums, where you can post
messages and read replies on many
subjects relating to ColdFusion
http://webforums.macromedia.com/
coldfusion/
Information on
JRun
Detailed product information on JRun and
related topics.
http://www.macromedia.com/products/jrun/
JRun Support
Center
Professional support programs that
Macromedia offers.
JRun Support Center
http://www.macromedia.com/
support/jrun
JRun Online
Forums
Access to experienced JRun developers
through participation in the Macromedia
Online Forums, where you can post
messages and read replies on many
subjects relating to JRun.
http://webforums.macromedia.com/jrun
Installation
Support
Support for installation-related issues for
all Macromedia products
http://www.macromedia.com/support/email/
isupport
Training Information about classes, on-site training,
and online courses offered by Macromedia
http://www.macromedia.com/support/training
ColdFusion
Developer
Resources
All the resources that you need to stay on
the cutting edge of ColdFusion
development, including online discussion
groups, Knowledge Base, technical
papers, and more
http://www.macromedia.com/desdev/
developer/
ColdFusion
Reference Desk
Development tips, articles,
documentation, and white papers
http://www.macromedia.com/v1/developer/
TechnologyReference/index.cfm

About Macromedia documentation ix
About Macromedia documentation
Macromedia documentation is designed to provide support for the complete spectrum of
participants. The print and online versions are organized to let you quickly locate the
information that you need. The Macromedia online documentation is provided in
HTML and Adobe Acrobat formats.
Viewing online documentation
All Macromedia documentation is available online in HTML and Adobe Acrobat
Portable Document Format (PDF) files.
The PDF files are included on the product CDs and are installed in the docs directory,
although they are an optional part of the installation.
JRun Developer
Resources
All of the resources that you need to stay
on the cutting edge of JRun development,
including online discussion groups,
Component Exchange, Resource Library,
technical papers, and more.
http://www.macromedia.com/desdev/
developer/
Macromedia
Alliance
Connection with the growing network of
solution providers, application developers,
resellers, and hosting services creating
solutions with ColdFusion
http://www.macromedia.com/partners/
Resource Description URL

x About This Book
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1
CHAPTER 1
Before You Begin
ClusterCATS is a web server clustering technology that provides load-balancing and
failover services that assure high availability for your web servers. ClusterCATS lets you
cluster distributed servers into a single, high-performance, highly available environment
of web server resources.
A cluster consists of two or more web servers located on a LAN or across a WAN. Web
servers included in a cluster operate as a single entity to provide rapid and reliable access
to resources on those web servers. A cluster can help your website avoid the consequence
of busy and failed servers — slow networks. With ClusterCATS you can avoid
bandwidth, latency, and congestion problems.
Contents
•ClusterCATS overview............................................................................................. 2
•ClusterCATS components ....................................................................................... 6
•System requirements................................................................................................ 7

2 Chapter 1 Before You Begin
ClusterCATS overview
The ClusterCATS technology provides robust features for website availability, load
balancing, and failing-over servers.
A website is no longer just a web server. Most websites have moved beyond static HTML
pages on a web server. To generate dynamic content or process transactions, a website
now includes multiple resources — web servers, files, applications, databases, and other
software processes on multiple servers in one or more locations. The move to a more
advanced site, consisting of multiple resources, often from multiple vendors, introduces a
major problem — overall site availability and performance. More resources, especially
software resources, and more links between them exponentially increase the probability
of failure. Creating a fast, reliable website becomes substantially more challenging.
Macromedia created ClusterCATS, a complete website resource management solution, to
enable service level agreements offering 24x7 availability and optimal response time for
e-commerce, customer self-service, sales automation, customer support, and other critical
business functions. With ClusterCATS, you can build and manage advanced websites,
consisting of multiple resources spanning multiple servers, in one or more locations.
ClusterCATS builds and manages clusters. A cluster is a group of website resources,
including web servers, files, applications, databases, and even the network, that act in
unison, providing reliable and rapid user access. These resources can be clustered in a
single building, distributed in a local area network (LAN), or distributed in a wide-area
network (WAN) in multiple locations across the world. A cluster intelligently detects and
transparently shields users from the following critical problems:
•Failed and busy servers
•Failed and busy applications and databases
•Slow networks caused by congestion, latency, and bandwidth problems
ClusterCATS capabilities
ClusterCATS delivers critical capabilities required by advanced websites today. These
capabilities produce important benefits in the areas of website performance, availability,
manageability, and scalability.
User response time is accelerated with ClusterCATS application and server load
management.
ClusterCATS consists of server and client components. The ClusterCATS Server runs as
a Windows service and ISAPI filter, NSAPI plug-in, or Apache module. ClusterCATS
Explorer is the client-based management application used to build and manage clusters.
Operating in conjunction with an administrative agent on each ClusterCATS Server,
ClusterCATS Explorer provides all the required tools for centrally managing one or more
clusters from any location.
You can also configure ClusterCATS software to enhance simple web server
load-balancing products, such as Cisco’s special-purpose LocalDirector hardware device.

ClusterCATS overview 3
The following table introduces the ClusterCATS capabilities:
Detailed overview
Application and server load management
ClusterCATS improves user response time by managing application load and web server
load across multiple servers.
You establish load management policy through two administrator-defined response time
thresholds. You configure these for each server. One threshold sets the level at which load
management is activated. If this level of activity is reached, ClusterCATS gradually
redirects a percentage of new server requests to the least-loaded server.
The other threshold defines the peak, or maximum, load level. This is defined as the load
level that should not be reached on that server. If this threshold is attained, an alarm is
sent and requests is redirected.
Feature Description
Application and server
load management
Allows administrators to configure server load thresholds to
provide optimum user response time in JRun/ColdFusion
applications. ClusterCATS Server load management protects
users from overloaded servers.
Server failover Provides seamless failover of a web server because of a
hardware, software, or network connection to another member in
the cluster. ClusterCATS shields users from unplanned or
planned server failures.
Session state
management
Allows session state to be maintained across your website using
a unique method that eliminates the source IP address server
overload problems caused by proxy users. ClusterCATS
application state management ensures users are not redirected
away from a server while maintaining state.
Application monitor You can configure ClusterCATS to monitor the JRun/ColdFusion
server or a JRun/ColdFusion application, and restart the server or
application if a failure occurs.
Distributed operations Exploits a distributed operations model, eliminating traffic
bottlenecks and maximizing performance and availability. All
servers share knowledge of application or web server
performance, and server availability. Each server can respond
directly to a request or redirect a request to a faster server.
Centralized
management
Provides a central console to manage and configure all web
servers in your cluster. ClusterCATS Explorer provides both
high-level and detailed views of the status of one or more
websites and all the resources within a website.

4 Chapter 1 Before You Begin
Session state management and failover
For some applications, it is important that a user session is completed on one server.
ClusterCATS offers a session state management option that ensures that the same web
server services requests from a user. When enabled, this option sends the user to the
best-performing server. The user session then remains on that server until completion.
ClusterCATS defines a new session for the following:
•A user comes from a different domain
•A user enters a new URL
•A user employs a bookmark
This approach has distinct advantages over other methods, such as using a source IP
address to define a user session. The ClusterCATS definition of a session is particularly
beneficial if many visitors come from a large proxy server (for example, America Online).
In that scenario, web servers could easily become overloaded.
Should user state be lost completely due to a resource failure, ClusterCATS provides
graceful state failover. This capability automatically displays an administrator-defined
URL for a custom HTML page or JRun page upon resource failure. This page can be
designed to apologize for the failure and, if replicated resources are available, direct the
user to restart the application at the beginning via a specific URL.
Distributed operations
ClusterCATS uses a distributed operations model, eliminating traffic bottlenecks and
maximizing performance. While other hardware and software load-balancing solutions
force all user requests and, typically, all responses through a single special-purpose
network device or server, each ClusterCATS Server can receive a request, respond to a
request, manage traffic load, and support failover. Unlike hardware load-balancing
solutions, ClusterCATS performance is not throttled by network media limitations and
ClusterCATS is network media independent. Consequently, performance scales linearly
as servers and resources are added.
Centralized management
ClusterCATS Explorer, operating in conjunction with an administrative agent on each
ClusterCATS Server, provides all the required tools for building and managing a website
from any location, whether it be an operations center, hotel, or home.
ClusterCATS Explorer features a familiar Windows Explorer-like user interface and
provides both detailed and high-level status views of one or more websites and all
resources within a website.
ClusterCATS Explorer views include:
•Simplifies user interface for the configuration tasks of building a website, including
adding and removing resources, setting load thresholds, selecting alarms, designating
administrators, configuring replication, and state management capabilities
•Real-time graphs of the actual application or HTTP server load and load thresholds

ClusterCATS overview 5
ClusterCATS product configurations
ClusterCATS includes a comprehensive core set of features and offers several add-on
options for extending its capabilities. All ClusterCATS configurations include:
•Macromedia Enterprise Server (ColdFusion and JRun) load manager
•Configurable load thresholds
•Real-time load monitor
•Session state management (server level)
•HTTP server monitor and auto-restart
•Real-time web server availability monitor
•Web server failover option
•Web server restriction
•Macromedia Enterprise Server monitor and auto-restart
•Macromedia Enterprise Server application monitor and auto-restart
•Administrator authentication
•Alarms
•Daily reports

6 Chapter 1 Before You Begin
ClusterCATS components
ClusterCATS consists of these primary components:
•Server Resides on each computer in a cluster. It communicates with the web server
and other ClusterCATS Servers. For more information, see “ClusterCATS Server” on
page 48.
•Server Administrator (Windows only) or btadmin Lets you perform server-specific
administration tasks through a graphical interface. For UNIX-based administration,
use the scriptable btadmin utility, which is also available for Windows users. For more
information, see “ClusterCATS Server Administrator” on page 52 and “Using
btadmin” on page 122.
•ClusterCATS Explorer and Web Explorer Graphical utilities for creating and
managing clusters in Windows and UNIX environments, respectively. For more
information, see “ClusterCATS Explorer (Windows only)” on page 48 and
“ClusterCATS Web Explorer (UNIX only)” on page 49.
The following table shows which components ClusterCATS installs on each platform:
You must run the installation program on each server that will be part of your cluster and
on the Windows computer (NT, 2000, .NET Server, 98, or 95) from which you will use
ClusterCATS Explorer to administer the cluster. Even if your clusters run on Solaris or
Linux platforms, obtain a Windows computer for running ClusterCATS Explorer. If you
cannot, use the ClusterCATS Web Explorer in conjunction with the included server
utilities to administer your clusters.
Windows Installation UNIX Installation
ClusterCATS Server ClusterCATS Server
btadmin and ClusterCATS Server
Administrator
btadmin (Note: You can administer a UNIX cluster
with the ClusterCATS Server Administrator from a
Windows computer outside the cluster.)
ClusterCATS Explorer ClusterCATS Web Explorer (Note: You can access
this from a Windows or UNIX computer.)

System requirements 7
System requirements
This section describes the platforms on which the ClusterCATS components run and
their minimum system requirements.
ClusterCATS Server system requirements
You must install the ClusterCATS Server component on each server in your cluster.
Ensure that your server meets the minimum system requirements for your platform.
Windows system requirements for ClusterCATS Server
•Intel Pentium 200 Mhz or greater CPU
•100 MB of free disk space
•128 MB of RAM
•Windows NT (with SP 4 or greater), Windows 2000, or Windows .NET Server
•Internet Information Server or greater; Netscape Enterprise Server v3.5.1 or greater
•Administrative privileges on each server
•A unique IP address assigned to each web server
•Correct DNS entries and configurations (see “Configuring DNS servers” on page 34)
Note: ClusterCATS Server does not run on Windows 98 or Windows 95.
Sun Solaris system requirements for ClusterCATS Server
•Sun SPARC workstation
•100 MB of free disk space
•128 MB of RAM (more recommended)
•Solaris operating system v2.51 or greater with Patch 103582-18 or higher
•Netscape Enterprise Server v3.5.1 or greater or Apache Web Server v1.3.6 or greater
•Administrative root privileges on each server
•A unique IP address assigned to each web server
•Correct DNS entries and configurations (see “Configuring DNS servers” on page 34)
Linux system requirements for ClusterCATS Server
•Intel Pentium 200 Mhz or greater
•100 MB of free disk space
•128 MB of RAM (more recommended)
•Red Hat operating system v6.0 or greater
•Apache Web Server v1.3.6 or greater
•Administrative root privileges on each server
•A unique IP address assigned to each web server
•Correct DNS entries and configurations (see “Configuring DNS servers” on page 34)

8 Chapter 1 Before You Begin
ClusterCATS Explorer and Web Explorer system requirements
You can install the ClusterCATS Explorer or Web Explorer component on a computer
outside the cluster, so you can administer the cluster from a central location. Ensure the
computer on which you install one of these components meets the minimum system
requirements.
System requirements for the Windows-based Explorer
The Windows-based ClusterCATS Explorer runs from a Windows computer (NT, 2000,
.NET Server, 98, or 95), regardless of the platform on which you install ClusterCATS
Server. Its system requirements are as follows:
•Intel Pentium 200 Mhz or greater CPU
•100 MB of free disk space
•64 MB of RAM (128 MB recommended)
•Windows NT Service Pack 5 or greater (if running Windows NT)
•Administrative privileges
System requirements for the ClusterCATS Web Explorer
Use the ClusterCATS Web Explorer if you have a UNIX-only environment. Install the
ClusterCATS Web Explorer program on a UNIX server that meets the following
requirements:
•Sun SPARC workstation
•75 MB of free disk space
•128 MB of RAM
•Solaris operating system v2.51 or greater with Patch 103582-18 or higher
•Netscape Enterprise Server v3.5.1 or greater or Apache Web Server v1.3.6 or greater
•Microsoft Internet Explorer 4.0 or greater or Netscape Navigator 3.0 or greater

9
CHAPTER 2
Scalability and Availability Overview
This chapter describes the concepts involved in achieving scalable and highly available
web applications.
Contents
•What is scalability? ................................................................................................ 10
•Successful scalability implementations ................................................................... 13
•What is website availability?................................................................................... 23
•Creating scalable and highly available sites............................................................. 28

10 Chapter 2 Scalability and Availability Overview
What is scalability?
As an administrator, you probably hear about the importance of having web servers that
scale well. But what exactly is scalability? Simply, scalability is a web server’s ability to
maintain a site’s availability, reliability, and performance as the amount of simultaneous
web traffic, or load, hitting the web server increases.
The major issues that affect website scalability include:
•“Performance” on page 10
•“Load management” on page 12
Performance
Performance refers to how efficiently a site responds to browser requests according to
defined benchmarks. You can design, tune, and measure application performance.
Performance can also be affected by many complex factors, including application design
and construction, database connectivity, network capacity and bandwidth, back office
services (such as mail, proxy, and security services), and hardware server resources.
Web application architects and developers must design and code an application with
performance in mind. When the application is built, administrators can tune
performance by setting specific flags and options on the database, the operating system,
and often the application itself to achieve peak performance. Following the construction
and tuning efforts, quality assurance testers should test and measure an application’s
performance prior to deployment to establish acceptable quality benchmarks. If these
efforts are performed well, you can better diagnose whether the website is operating
within established operating parameters, when reviewing the statistics generated by web
server monitoring and logging programs.
Depending on the size and complexity of your web application, it may be able to handle
from ten to thousands of concurrent users. The number of concurrent connections to
your web server(s) ultimately has a direct impact on your site’s performance. Therefore,
your performance objectives must include two dimensions:
•Speed of a single user’s transaction
•Amount of performance degradation related to the increasing number of concurrent
users on your web servers
Thus, you must establish response benchmarks for your site and then achieve the highest
number of concurrent users connected to your site at the response rates. By doing so, you
will be able to determine a rough number of concurrent users for each web server and
then scale your website by adding additional servers.
When your site runs on multiple web servers, you must monitor and manage the traffic
and load across the group of servers. To learn how to do these tasks, see “Hardware
planning” on page 26 and “Creating scalable and highly available sites” on page 28.