macromedia ® Using ClusterCATS
Trademarks Afterburner, AppletAce, Attain, Attain Enterprise Learning System, Attain Essentials, Attain Objects for Dreamweaver, Authorware, Authorware Attain, Authorware Interactive Studio, Authorware Star, Authorware Synergy, Backstage, Backstage Designer, Backstage Desktop Studio, Backstage Enterprise Studio, Backstage Internet Studio, ColdFusion, Design in Motion, Director, Director Multimedia Studio, Doc Around the Clock, Dreamweaver, Dreamweaver Attain, Drumbeat, Drumbeat 2000, Extreme 3D, Fireworks,
CONTENTS ABOUT THIS BOOK . . . . . . . . . . . . . . . . . . . . . . . . . . . VII Developer resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii About Macromedia documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Viewing online documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Contacting Macromedia . . . . . . . . . . . . . . . .
CHAPTER 3 Installing ClusterCATS . . . . . . . . . . . . . . . . . . . . . . . . 33 Before you install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Upgrading from a previous version of ClusterCATS. . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Configuring DNS servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Configuring server failover . . . . . . . . . . . . . . . .
Load-balancing devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92 Using Cisco LocalDirector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92 Using third-party load-balancing devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Administrator alarm notifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 ....................................................
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.
Resource Description URL JRun Developer Resources http://www.macromedia.com/desdev/ All of the resources that you need to stay on the cutting edge of JRun development, developer/ including online discussion groups, Component Exchange, Resource Library, technical papers, and more. Macromedia Alliance http://www.macromedia.
Contacting Macromedia Corporate headquarters Macromedia, Inc. 600 Townsend Street San Francisco, CA 94103 Tel: 415.252.2000 Fax: 415.626.0554 Web: http://www.macromedia.com Technical support Macromedia offers a range of telephone and web-based support options. Go to http://www.macromedia.com/support for a complete description of technical support services. Sales Toll Free: 888.939.2545 Tel: 617.219.2100 Fax: 617.219.2101 E-mail: sales@macromedia.com Web: http://www.macromedia.
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.
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 following table introduces the ClusterCATS capabilities: 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.
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 product configurations ClusterCATS includes a comprehensive core set of features and offers several add-on options for extending its capabilities.
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.
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.
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, .
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?..................................................................................
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.
Linear scalability Perfect scalability — excluding cache initializations — is linear. Linear scalability, relative to load, means that with fixed resources, performance decreases at a constant rate relative to load increases. Linear scalability, relative to resources, means that with a constant load, performance improves at a constant rate relative to additional resources. Caching and resource management overhead affect an application server’s ability to approach linear scalability.
Load management Load management refers to the method by which simultaneous user requests are distributed and balanced among multiple servers (Web, JRun, ColdFusion, DBMS, file, and search servers). Effectively balancing load across your servers ensures that they do not become overloaded and eventually unavailable.
Successful scalability implementations Achieving scalable web servers is not a trivial task. There are various solutions from which to pick, setup and configuration tasks to understand and perform, and many delicate dependencies between related but heterogeneous technologies.
Web developers must think through the user scenarios in which application session and state are affected, and engineer appropriate mechanisms to handle them. The most common ways to handle session data are: • Client-side options consisting of cookies, hidden fields, a get list, or URL parameters • Server-side session variables Note: Storing session data on the server requires that a simple identifier is stored on the client, such as a cookie.
Application partitioning The way an application is partitioned and deployed dramatically affects its ability to scale. A key development objective must be to ensure that each partition scales independently of the others, thereby eliminating application bottlenecks. Application partitioning refers to the logical and physical deployment of an application’s three core types of logic, or services — presentation, business, and data access.
cleanly display all technologies, such as cascading style sheets (CSS), Java applets, and frames, you must carefully evaluate their use in your applications. Bear in mind these presentation guidelines, to aid your applications’ performance and user experience, and be sure to plan and test for the lowest common denominator that all browsers can accommodate.
• Network connectivity and bandwidth — consider the type of network your application will run on (LAN/WAN/Internet) and how much traffic it typically receives. If traffic is consistently heavy, you may need to add additional nodes, routers, switches, or hubs to the network to handle the increased traffic. • Databases — database access, while vitally important to your application’s capabilities and feature set, can be costly in terms of performance and scalability if it is not engineered efficiently.
To understand why, let’s look at the e-commerce example.
The following figure shows these concepts: DNS servers store information about the domain name space and are referred to as name servers. Name servers typically have one or more zones for which they are responsible. The name server has authority for those zones and is aware of all the other DNS name servers that are in the same domain.
The DNS entries would look like the following: : ; Entries for forward-resolution: A-records www1.yourcompany.com IN A 192.168.0.1 www2.yourcompany.com IN A 192.168.0.2 192.168.0.1 PTR www1.yourcompany.com 192.168.0.2 PTR www2.yourcompany.com www.yourcompany.com IN A 192.168.0.1 www.yourcompany.com IN A 192.168.0.
hitting your web server. By using the software in conjunction with your defined benchmarks and formal test plans, you can confidently determine whether your web application is ready for deployment. Another reason to load test is to verify your failover capabilities. Failover ensures that if a primary server within a cluster of servers stops functioning, subsequent user requests are directed to another server within the cluster.
Load-testing considerations Before starting your load testing, consider the following: • Define benchmarks early — ensure that you understand your website’s performance and scalability requirements before you start running tests against it. Otherwise, you won’t know what you’re testing for and the statistics you capture won’t have significance.
What is website availability? It is critical to design, develop, test, and deploy web applications so they can scale well under heavy and ever-increasing load. However, in spite of the best-laid plans and preparations, servers can fail for seemingly unknown reasons, causing your site to become unavailable. If and when a server fails or becomes overloaded, you want to ensure that the failure won’t adversely affect your business by preventing your customers from accessing and using your web application.
For JRun and ColdFusion web applications, it is particularly important that the servers remain as highly available and responsive as the web server and other dependent servers. JRun and ColdFusion process requests sent to them from the web server. Upon successfully processing the application logic, JRun and ColdFusion return the results to the web server, which in turn returns an HTML response to the browser.
Website availability scenario Imagine that you have just built a robust, interactive e-commerce website on which you plan to sell the most sought-after books and music in the world. You have used Java scriptlets to build the application, so of course you’ve taken advantage of its many built-in features, including secure database access, multithreading, and integrated session management.
Hardware planning As indicated in the availability example above, you must acquire all necessary hardware and configure it before you deploy an application. All websites have different requirements, feature sets, purposes, audiences, and budgets, and therefore different needs. However, if your site is a business-critical system that affects your company’s bottom line, you must ensure an appropriate redundancy strategy by having two or more redundant systems in place.
However, before the analysis and repair can occur, the administrator must be notified. Whatever failover system you put in place, it should include an automated notification system that can route alerts through your telecommunications infrastructure (e-mail, pagers, real time Web-based alerts, and so on) to the appropriate administrator for prompt attention.
Creating scalable and highly available sites When you understand the issues of scalability and availability, the next step is to learn the techniques you can use to achieve scalable and highly available websites.
Hardware-based clustering solutions A common and reliable hardware-based clustering solution is a packet router. One of the most popular routers is Cisco Systems’ LocalDirector. A router, in front of a cluster of web servers, directs incoming HTTP requests to available web servers in the cluster. A router works by assessing the rate and volume of IP packet flow to and from web servers, and selecting the best server to accommodate the traffic. This process is fast and efficient.
• There are no recurrent licensing fees • It is semi-intelligent; routers can load balance in a round-robin fashion, detect failures, redirect traffic, and remove failed servers from a cluster. Note: Load-balancing devices offer different features and capabilities. Considerations Carefully evaluate the following issues against a router’s attributes: • Expense — hardware devices can be expensive relative to some software solutions, even without yearly licensing fees.
Advantages The following benefits make a software-based clustering solution attractive: • Relatively low expense — compared to the cost of hardware devices, such as routers or switches, software-based clustering solutions are relatively inexpensive. In fact, you can cheaply implement Internet DNS on UNIX and Windows platforms for initial load-balancing needs, and augment with third-party clustering software.
Combining hardware and software clustering solutions Instead of having to choose either a hardware solution or a software solution, you can combine both types of clustering choices. Combining hardware and software solutions certainly provides the greatest scalability and availability capabilities for a site. A combined solution is an attractive option if your organization has already invested in one, but is looking for more comprehensive coverage.
CHAPTER 3 Installing ClusterCATS Before installing ClusterCATS, you must make many important decisions about the architecture of your website. Use the first section in this chapter to guide you through the decision-making process. When you have installed ClusterCATS, read the last section in this chapter for important information on how to make your site secure and reliable. Contents • Before you install ...................................................................................................
Before you install Before installing ClusterCATS and creating server clusters, you must perform the following pre-installation tasks: • “Upgrading from a previous version of ClusterCATS” on page 34 • “Configuring DNS servers” on page 34 • “Configuring server failover” on page 38 • “Using ClusterCATS dynamic IP addressing” on page 38 • “Configuring firewalls” on page 38 • “Analyzing web server content” on page 39 • “Considering domain controllers (Windows NT only)” on page 40 Upgrading from a previous versi
The primary DNS server contains tables of forward and reverse name translations. For example, forward translation entries (A records) look like this: www1.company.com 192.168.0.1 www2.company.com 192.168.0.2 Reverse translation entries (PTR records) are opposite, and look like this: 192.168.0.1 www1.company.com 192.168.0.2 www2.company.com Configure your websites with forward and reverse DNS entries on your primary DNS server.
The following diagram shows this process: Configuring your primary DNS server You must configure DNS so the forward and reverse lookup translation entries are entered and registered correctly with your primary DNS server. To do this, you must define DNS A and PTR DNS records for the web servers on your primary DNS server. Besides standard name translations, your primary DNS server can distribute HTTP requests sequentially across clustered servers, using a technique called round-robin DNS.
Using ClusterCATS with round-robin DNS For high-volume sites, you should use round robin DNS to initially distribute requests to the web servers in your cluster. The load management component of ClusterCATS enhances round-robin DNS by eliminating its two major limitations: • Server failure — round-robin DNS cannot detect server failure. Should a server in a cluster fail, another server on the subnet immediately and transparently assumes the IP address of the failed server.
Round-robin DNS distributes the initial domain-level requests across all four servers. Thereafter, ClusterCATS distributes load to avoid failed or overloaded servers. Configuring server failover ClusterCATS protects clusters from server hardware and software failures. When a server is no longer sending or receiving packets from the network, its IP address (and, therefore, its HTTP requests) are assumed by another cluster member, which picks up HTTP traffic originally addressed to the failed server.
from behind another firewall, you must open both ports so the ClusterCATS Explorer can communicate with the cluster. The following diagram shows this scenario: This scenario involves Company ABC, which has East Coast and West Coast server groups connected to the Internet, protected by several firewalls. The ClusterCATS Explorer resides at the corporate headquarters behind a firewall with a direct connection to the Internet.
Considering domain controllers (Windows NT only) If you use Windows NT Domain server authentication, each web server in a cluster must participate as a member NT server in a domain. Do not set a server in your cluster as the primary domain controller (PDC). ClusterCATS Server failover will interfere with the function of the PDC. An NT server can be a backup domain controller, but this is not the recommended configuration.
Installing ClusterCATS ClusterCATS is a separate installation package from the JRun server installation program. You must install the ClusterCATS load-balancing and high-availability software on each servers in your cluster. You can run the installation program to install ClusterCATS on a separate, nonclustered computer from which you will administer your clusters with ClusterCATS Explorer (Windows).
The following table describes your options: Method Reason to Select Option HyperText Transport Protocol (HTTP) To have ClusterCATS load manage just your web server’s HTTP requests. JRun (JSP) To have ClusterCATS load manage your JRun server’s JSP and servlet requests. ColdFusion (CFM) To have ClusterCATS load manage your ColdFusion server’s CFML page requests. You must have ColdFusion Server installed for this option to take effect.
3 Review the license.txt file that is supplied with ClusterCATS. If you agree with the licensing terms, enter Yes at the prompt. If you do not agree with the licensing terms, enter No. Entering No terminates the installation procedure. The installation directory prompt appears. Enter install directory for ClusterCATS Server: [/opt]: 4 Enter the base directory where ClusterCATS will be installed, or press Enter to accept the default. The installation creates a ./btcats subdirectory under the base directory.
If you are configuring ClusterCATS with Netscape and selected Yes, you are prompted to decide which servers in the cluster this server will provide failover support for: Cluster Mates to provide Failover for: all, subset, none [all]: 10 Netscape only: Enter all to provide failover support to all members of this server’s cluster. Enter subset to explicitly define the cluster members for which this server will provide failover support. Enter none to disable server failover.
After you install When you have successfully installed ClusterCATS on all members of the cluster and any administrative computers, you are ready to create your first cluster. If you administer ClusterCATS from a Windows computer, you can use the Cluster Setup Wizard described in “Creating clusters with the Cluster Setup Wizard” on page 54, or manually create the cluster using the procedure described in “Creating clusters” on page 54.
46 Chapter 3 Installing ClusterCATS
CHAPTER 4 Configuring Clusters When you have configured your website and installed ClusterCATS, use the procedures in this chapter to create and configure clusters. Contents • Introduction to ClusterCATS Administration........................................................ 48 • Creating clusters .................................................................................................... 54 • Removing clusters..........................................................................................
Introduction to ClusterCATS Administration ClusterCATS consists of these components: • ClusterCATS Server • ClusterCATS Explorer and ClusterCATS Web Explorer • ClusterCATS Server Administrator and btadmin The following sections describe these components. All the components are installed on a computer when you run the ClusterCATS installation program.
Note: You can run the ClusterCATS Explorer from any server in the cluster, or you can run it remotely. This flexibility gives administrators in different geographic locations the ability to administer distributed clusters. You can also use ClusterCATS Explorer to administer UNIX clusters from a single Windows computer. You can view multiple clusters from a single Explorer.
• Monitor the load hitting the server via a graphical display; the server’s load statistics are only displayed textually on the Cluster Member List and Server Properties pages • Integrate ClusterCATS with Cisco LocalDirector If you require any of these capabilities, you should obtain a Windows computer and use the Windows-based ClusterCATS Explorer for your cluster administration.
AuthUserFile /usr/local/apache/conf/users require user admin When you have configured your server, restart Apache. To access the Web Explorer, point your browser to the IP address you entered as the VirtualHost. For information on using the htpasswd utility to create and manage your authentication file list, see the Apache documentation.
ClusterCATS Server Administrator The ClusterCATS Server Administrator is a Windows-based utility that lets you perform server-specific maintenance activities for each server in a cluster. Unlike the ClusterCATS Explorer, which let you administer clusters from one central computer, you must run the ClusterCATS Server Administrator from each server in your cluster.
btadmin btadmin is a scriptable utility that lets you perform server-specific maintenance activities for each server in a cluster. btadmin is available on UNIX and Windows servers. Unlike the ClusterCATS Web Explorer, which lets you administer your entire cluster from one central computer, you must use btadmin from each server in your cluster.
Creating clusters If you have performed the tasks described in “Before you install” on page 34 and you have successfully installed ClusterCATS, you are ready to create server clusters. This section explains the following: • “Creating clusters in Windows” on page 54 • “Creating clusters in UNIX” on page 60 Creating clusters in Windows You can create clusters using the Cluster Setup Wizard or manually, using the ClusterCATS Explorer.
The Create New Cluster dialog box appears: 3 Enter a name for your cluster and click Next. Make your cluster names logically consistent with their purpose. For example, Sales Web, Customer Support Web, and so on.
4 Click Add to add available web servers to your cluster. The Add New Server to Cluster dialog box appears: 5 Enter the fully qualified host name of a web server in the New Web Server Name field (for example, doc.macromedia.com). 6 If you use the ClusterCATS dynamic IP addressing scheme and the maintenance IP address is not bound to your NIC, select ClusterCATS Maintenance Support. If you are not configuring this server for offline maintenance support, go to step 8.
10 To use the default load threshold settings, click Next and go to step 13. If you do not want to use the defaults, select the server and click Configure to configure new peak and gradual redirect load thresholds for that cluster member. The Load Thresholds dialog box appears: 11 Enter numerical values (not higher than 100%) in the Peak Load Threshold and Gradual Redirect fields and click OK. Set the peak load threshold below 100%, to accommodate the server’s processing needs.
manually change the few recipients that are different. If there are multiple recipients for one alert event, separate e-mail address entries with commas. Click OK to return to the Alarm Notifications dialog box and then click Next to proceed. The Session State Management dialog box appears: 16 If your server cluster supports a site that must maintain persistent state on the same web server during a user session, select Yes to enable session-aware load balancing. Otherwise, select No and click Next.
Manually creating clusters If you do not want to create your clusters using the Cluster Setup Wizard, you can create them manually. If you manually create clusters, you must then add each cluster member to a cluster, using the ClusterCATS Explorer. To manually add cluster members to a cluster, see “Adding cluster members” on page 63. To manually create clusters: 1 Select Start > Programs > Macromedia > ClusterCATS Explorer. The ClusterCATS Explorer opens.
Field Description ClusterCATS maintenance support Select the ClusterCATS Maintenance Support check box to enable support for offline maintenance. The Admin Manager must be configured with a maintenance IP address. Using maintenance support requires that your cluster support ClusterCATS dynamic IP addressing. For more information, see “ClusterCATS dynamic IP addressing (Windows only)” on page 132. Offline maintenance support is available only on Windows NT server clusters.
2 Add a cluster using the fields as described in the following table: Field Cluster Name Description Enter a unique name for the cluster. Make cluster names logically consistent with their purpose — for example, Sales Web, or Customer Support Web. Web Server Name Enter the fully qualified host name (for example, doc.macromedia.com) for the first server you want to be a member of this cluster. You cannot create an empty cluster; you must specify a web server that will be part of the cluster.
Removing clusters To delete a cluster, you must delete each member from the cluster individually, using the procedure described in “Removing cluster members” on page 65. Note: When deleting cluster members, you must delete the Admin Manager (Windows) or the Admin Agent (UNIX) last. This server is the first server you added to the cluster. When the last cluster member has been removed, the cluster itself is deleted. To determine which server is the Admin Manager in Windows: 1 Open the ClusterCATS Explorer.
Adding cluster members You can add servers to a cluster at any time. This section describes the following: • “Adding cluster members in Windows” on page 63 • “Adding cluster members in UNIX” on page 64 Adding cluster members in Windows Use the ClusterCATS Explorer to add servers to a cluster. If you used the Cluster Setup Wizard (Windows only) to create a cluster and populate it with cluster members, you can also add clusters using the following procedure.
Adding cluster members in UNIX Use the ClusterCATS Web Explorer to add cluster members. To add a cluster member to a cluster: 1 Open the ClusterCATS Web Explorer if it is not already open. 2 Click the Add Server link. The Add Server page appears: 3 Enter the fully qualified host name (for example, doc.macromedia.com) in the Web Server Name field. 4 Click OK to add the cluster member to the existing cluster.
Removing cluster members You can remove servers from a cluster at any time. This section describes the following: • “Removing cluster members in Windows” on page 65 • “Removing cluster members in UNIX” on page 65 Removing cluster members in Windows Use the ClusterCATS Explorer to remove cluster members. To remove a cluster member from a cluster: 1 Open the ClusterCATS Explorer and select a cluster member. 2 Select Server > Delete or right-click the server name and select Delete.
Server load thresholds ClusterCATS ensures that your web applications remain available and running at optimum performance by intelligently managing the HTTP traffic hitting your clustered servers. By setting load thresholds on each server in your cluster, you can control and manage your site’s availability and performance. Many of your threshold configuration decisions hinge on your site’s architecture and where the bulk of your processing resources must be allocated.
The server’s Properties dialog box appears: 3 Click the Load tab. 4 Enter a numeric value (less than 100%) in the first Load Management field. This is referred to as the peak load threshold. In the example above, the peak load threshold is set to 90. 5 Enable the Gradual Redirection check box. 6 Enter a new value in the Gradual Redirection field. This value must be lower than the peak load threshold. 7 Click OK to apply your new threshold settings.
Viewing a cluster’s load status JRun/ColdFusion reports its load data directly to ClusterCATS. You can view the load on the servers at any time using the Server Load Monitor. To view your cluster’s current load levels: 1 Open the ClusterCATS Explorer and select a cluster. 2 Select Monitor > Load or right-click the cluster you have selected and select Monitor > Load.
The Server Load dialog box appears: 3 Use your mouse to drag the peak load threshold (red) up or down. As you move the line, the peak load threshold percentage changes. 4 Enable gradual redirection by selecting the Gradual Redirection check box. 5 Drag the Gradual Redirection load threshold (yellow) to adjust it accordingly. 6 Close the dialog box to apply the load threshold settings you configured.
3 Click OK. The Cluster Member List page appears. If you get an "Error: Server could not be found", ensure that you used the correct, fully qualified server name and that the server is running. 4 Click the Server Attributes link. The Connect To Server page appears: 5 Select a server to connect to from the Web Server Name list box. 6 Click OK.
The selected server’s Server Properties page appears: 7 Click the Administration link under Server Attributes. The Server Administration page appears for the selected server: 8 To change the peak load threshold, enter a new numeric value (less than 100%) in the Standard Load Threshold field. 9 Enable the Gradual Redirection check box if it is not already enabled. 10 To change the Gradual Redirection load threshold, enter a new numeric value in the Gradual Load Threshold field.
Session-aware load balancing Managing a web application’s state in a clustered environment can be challenging. By default, web application, session, and server variables that are stored in memory or a repository during a user session do not persist during a server redirection. Consequently, the web server cannot maintain the application’s state correctly. To overcome this problem, ClusterCATS provides a session-aware load-balancing feature that lets you maintain application state in a clustered environment.
3 Click OK. The Cluster Member List page appears: 4 Click the Administration link under Cluster Attributes. The Cluster Administration page appears: 5 Select the Enable session-aware load balancing check box. 6 Click OK to enable session-aware load balancing for the selected cluster.
Persistent session failover in JRun JRun can be configured to enable session persistence, meaning that all session data is saved (persisted) upon the completion of every request. When a server that is servicing a client's session goes down, the client's active session data can be retrieved intact from a common data store (such as a JDBC database) by another server.
To enable session swapping on Windows: 1 Edit the registry (using regedit) and open the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BrightTiger\ Parameters 2 Add the following REG_DWORD value: SessionSwapping 1 3 Close the registry editor. 4 Repeat this procedure for every server in the cluster. To enable session swapping on UNIX: 1 Log in as the super user (root).
Using JDBC for session swapping To use JDBC for session swapping, the JRun server's local.properties file should contain the following properties: session.persistence.service=jdbc session.persistence.jdbc.class=allaire.jrun.session.JDBCSessionStorage session.persistence.jdbc.JDBCDriver=sun.jdbc.odbc.JdbcOdbcDriver session.persistence.jdbc.JDBCConnectionURL=jdbc:odbc:JRunSessions session.persistence.jdbc.JDBCSessionTable=sessions session.persistence.jdbc.JDBCSessionIDColumn=id session.persistence.jdbc.
Using ColdFusion probes ClusterCATS provides load-balancing and failover support for your web applications in two ways. First, it automatically interprets and reacts to the load metric that the ColdFusion server generates. Second, ClusterCATS lets you create web application monitors. These monitors can have multiple probes that periodically test the health and operation of the websites that the servers process.
To add a new monitor and ColdFusion probe: 1 Open the ClusterCATS Explorer and select a server. 2 Select Server > New Monitor. Alternatively, you can right-click the server and select New Monitor. The New Monitor dialog box appears: 3 Enter a name to assign to this probe’s monitor in the Name field and click OK.
4 Click the New Probe button . The ColdFusion Web Application Probe settings dialog box appears: 5 Configure the application probe settings as described in the following table: Field Description Web Server Select the name of the server from the drop-down list. Pathname Enter the absolute path to the ColdFusion probe. Do not change the default selection unless you installed ColdFusion to a directory other than the default installation directory.
Field Description Frequency (sec) Enter a time, in seconds, to indicate how often the probe checks the ColdFusion server. Probes that restart web applications should be configured to run no more frequently than the time it takes to stop and restart ColdFusion. This time is highly site-specific, because it depends on the system resources available on the servers and the volume of traffic at the site.
4 Click the New Probe button . The ColdFusion Web Application Probe settings dialog box appears: 5 Configure the application probe settings as described in the table on page 79. 6 Click Register to create the probe. 7 Close all open dialog boxes. An icon for the new probe appears under the Monitor Manager in the ClusterCATS Explorer. Removing ColdFusion probes To remove a ColdFusion probe: 1 Open the ClusterCATS Explorer.
9 To create a new probe, click New. The ColdFusion Application Probe page appears. If this is the first probe for this server or you clicked New to add another probe, the ColdFusion Application Probe page appears. 10 Configure the application probe settings as described in the following table: Field Description Status This is an informational field. If the probe is not registered, the Status displays Not registered. If the probe is registered, the Status displays Succeeding.
11 Click Register to create the probe. ClusterCATS begins to test the selected server immediately. Editing and removing ColdFusion probes To edit or remove a ColdFusion probe: 1 Open the ClusterCATS Web Explorer, if it is not already open. 2 Click the Show Cluster link. The Show Cluster page appears. 3 Enter the fully qualified host name of the server for which you want to configure the ColdFusion probe in the Web Server Name field. 4 Click OK. The Cluster Member List page appears.
Using JRun probes ClusterCATS provides load-balancing and failover support for your web applications in two ways. First, it automatically interprets and reacts to the load metric that the JRun servers generate. Second, ClusterCATS lets you create web application monitors. These monitors can have multiple probes that periodically test the health and operation of the websites that the JRun servers process.
To add a new monitor and JRun probe: 1 Open the ClusterCATS Explorer and select a server. 2 Select Server > New Monitor or right-click the server and select New Monitor. The New Monitor dialog box appears: 3 Enter a name to assign to this probe’s monitor in the Name field on the New Monitor dialog box and click OK.
4 Click the New Probe button . The JRun Application Probe settings dialog box appears: 5 Configure the application probe settings as described in the following table: Field Description Web Server Select the name of the server from the drop-down list. Pathname Enter the absolute path to the JRun probe. Do not change the default selection unless you installed JRun to a directory other than the default installation directory. Working directory Enter the absolute path to the probe’s working directory.
Field Description Timeout (sec) Enter a time to indicate how long ClusterCATS waits before a JRun server failure is registered. Do not set this value to less than 60 seconds, because ClusterCATS may restart the JRun server inadvertently (due to network congestion, for example), rather than detect an actual failure on the JRun server. Frequency (sec) Enter a time to indicate how often the probe checks the JRun server.
The monitor’s Properties dialog box appears: 3 Click the New Probe button . The JRun Application Probe settings dialog box displays. 4 Configure the application probe settings as described in the table in “Using JRun probes” on page 84. 5 Click Register to create the probe. 6 Close all open dialog boxes. An icon for the new probe appears under the Monitor Manager in the ClusterCATS Explorer. Removing JRun probes To remove a JRun probe: 1 Open the ClusterCATS Explorer.
Adding JRun probes To add a new JRun probe: 1 In the ClusterCATS Web Explorer, click the Show Cluster link. The Show Cluster page appears. 2 In the Web Server Name field, enter the fully qualified host name of a server for which to configure the JRun probe. 3 Click OK. The Cluster Member List page appears. 4 Click the Server Attributes link. The Connect To Server page appears. 5 Select a server to add a probe to from the Web Server Name list box. 6 Click OK. The selected server’s Properties page appears.
9 Configure the application probe settings as described in the following table: Field Description Status This is an informational field. If the probe is not registered, the Status displays Not registered. If the probe is registered, the Status displays Succeeding. Pathname Enter the path to the JRun probe. Do not change the default selection unless you installed ClusterCATS for JRun to a directory other than the default installation directory. The default is /usr/lib/btcats/ program/jrunprobe.
Field Description Frequency (sec) Enter a time to indicate how often the probe checks the JRun server. Probes that restart web applications should be configured to run no more frequently than the time it takes to stop and restart JRun. The time is highly site-specific, because it depends on the system resources available on the servers and the volume of traffic at the site.
Load-balancing devices You can configure ClusterCATS to work in conjunction with a third-party hardware load-balancing device or load-balancing software product to provide comprehensive load balancing and failover support for your server clusters.
LocalDirector dynamic-feedback command settings Use the LocalDirector dynamic-feedback command options as described in this section to optimize your LocalDirector setup. Note: Do not use the dynamic-feedback-pw command. ClusterCATS does not support secure DFP hosts. • dynamic-feedback -timeout — sets timeout to a value larger than the update frequency so LocalDirector does not prematurely terminate the connection with the cluster because of inactivity.
7 Select Cluster > Properties or Configure > Administration. Both menu selections display the Cluster Properties dialog box, as the following figure shows: 8 Click the Load Balance tab and choose Cisco LocalDirector from the Load Balancing Product drop-down list.
9 Edit the cluster properties as described in the following table: Field Description Website Alias Enter the name of the virtual server (www.yourcompany.com) you created in step 3. LocalDirector IP Address Enter the IP address of Cisco LocalDirector. DFP Agent Listen Port Enter the port number on which the cluster's DFP agent should listen for incoming LocalDirector connection requests. This should be the same port specified in the LocalDirector dynamic-feedback as described in step 5.
Using third-party load-balancing devices in Windows To integrate ClusterCATS with a third-party load-balancing device: 1 Configure the load-balancing device or software product as recommended by the manufacturer. 2 Open the ClusterCATS Explorer and select a cluster. 3 Select Configure > Administration or right-click the cluster and select Configure > Configure. The Cluster Properties dialog box displays. 4 Click the Load Balance tab.
Using third-party load-balancing devices in UNIX You cannot take advantage of ClusterCATS support of Cisco LocalDirector with ClusterCATS Web Explorer. This capability is available only in the Windows-based ClusterCATS Explorer. You can, however, configure Cisco LocalDirector as a third-party load-balancing device to work with ClusterCATS. To integrate ClusterCATS with a third-party load-balancing device: 1 In ClusterCATS Web Explorer, click the Show Cluster link.
Administrator alarm notifications The ClusterCATS alarm notification feature provides instant feedback about critical events that take place within a cluster. When an event triggers an alarm, ClusterCATS notifies one or more people by e-mail. The events that can trigger a notification are listed below. If an event you selected occurs, ClusterCATS sends an e-mail message to the designated person. The following table explains the notification schedule for each event. Event type Notification occurs...
Configuring administrator alarm notifications on UNIX To configure administrator alarm notifications: 1 In ClusterCATS Web Explorer, click the Show Cluster link. The Show Cluster page appears. 2 Enter the fully qualified host name of a server for which to configure administrator alarm notifications in the Web Server Name field. 3 Click OK. The Cluster Member List page appears. 4 Click the Alarm Notification link.
Administrator e-mail options The ClusterCATS administration e-mail support feature reports vital statistics about your cluster to designated e-mail accounts in your organization. You can set up the following types of administration e-mail options: • Report e-mail — lets you know each day how your server clusters are functioning.
3 Edit the e-mail support options as described in the following table: Field Description SMTP gateway Enter the name of the server through which outgoing e-mail is sent. Support e-mail Enter the e-mail address of a person in your organization to receive a copy of the nightly technical support e-mail. If more than one person should receive the e-mail, separate the addresses with commas. You do not have to enter a Macromedia Technical Support address.
5 Edit the e-mail support fields as described in the following table: Field Description SMTP Gateway Enter the name of the server through which outgoing e-mail is sent. Support e-mail Enter the e-mail address of a person in your organization to receive a copy of the nightly technical support e-mail. If more than one person should receive the e-mail, separate e-mail addresses with commas. You do not have to enter a Macromedia Technical Support address.
Administering security When you enable ClusterCATS administration security for a cluster, only authorized users are able to access and administer the cluster, using ClusterCATS Explorer (Windows) or the ClusterCATS Web Explorer (UNIX). ClusterCATS provides these administration security settings for securing your server cluster environment: • Disabled Authentication — this is the default setting.
To configure authentication modes for your clusters: 1 Create a user account on each server within your cluster for each administrator whom you want to be able to administer the servers using the ClusterCATS Explorer. If your cluster members are NT servers, use the Windows User Manager utility to create your user accounts. Note: If only one person will administer all cluster members in the cluster, be sure to create the same user account (identical user name and password) on each cluster member.
Configuring Windows NT domain authentication Windows NT Domain authentication lets ClusterCATS authenticate administrators who have been added to a Windows NT domain user group. Note: This authentication mode can be used only on NT servers and on Windows 2000 servers if the domain is using the Windows NT compatible domain controller model rather than the Active Directory model.
10 Select NT Domain from the Mode drop-down box. 11 Enter a valid user name and password that participates in the domain. Note: ClusterCATS requires you to enter a valid user name and password after selecting the authentication type, so you do not inadvertently lock yourself out of the cluster. 12 Click OK to enable Windows NT Domain authentication for the selected cluster.
The Cluster Authentication page appears: 5 Select Local User from the Authentication drop-down box to enable local-user authentication. 6 Select Disabled to disable authentication. 7 If using local user authentication, enter a valid user name and password and click OK. ClusterCATS requires you to enter a valid user name and password after selecting the authentication type, so you do not inadvertently lock yourself out of the cluster.
108 Chapter 4 Configuring Clusters
CHAPTER 5 Maintaining Cluster Members After you have created your clusters, added servers to them, and configured them with load-balancing and high-availability features, they will probably run inconspicuously in your environment for quite some time. However, at some point you may need to update software and content or perform general maintenance tasks that are beyond the typical cluster creation and configuration activities. Contents • Understanding ClusterCATS server modes ...............................
Understanding ClusterCATS server modes ClusterCATS lets you move cluster members into modes of operation depending on the tasks you want to perform on their server. The modes let you remove servers from clusters to perform maintenance activities without disturbing the current traffic flow, among other things. The following table describes the modes of operation into which you can place cluster members: Mode Description Active/Passive Setting Turns the ClusterCATS Server on and off.
Changing active/passive settings All cluster members are added to a cluster with the ClusterCATS Server in active state, by default. In active state, ClusterCATS Servers intercept requests to your web resources and provide availability and failover services. From time to time, you may want to turn off these load-balancing and failover services, to help troubleshoot problems. To do this, change the ClusterCATS Server’s state from active to passive.
Changing active/passive settings in UNIX To change a cluster member’s state: 1 In ClusterCATS Web Explorer, click the Show Cluster link. The Show Cluster page appears. 2 Enter the fully qualified host name of the server in the Web Server Name field. 3 Click OK. The Cluster Member List page appears. 4 Click the Server Attributes link under Other. The Connect To Server page appears. 5 Select a server to connect to from the Web Server Name drop-down box. 6 Click OK.
Changing restricted/unrestricted settings ClusterCATS lets you stop a cluster member from receiving HTTP requests by changing the restricted/unrestricted setting. You may want to restrict a server when performing server maintenance or software updates, verifying load configurations, or as an alternative method to managing load. Only cluster members in active mode can be restricted, because cluster members in passive mode do not receive any ClusterCATS Server intervention.
Restricting/unrestricting servers in UNIX To change restriction settings for a cluster member: 1 In ClusterCATS Web Explorer, click the Show Cluster link. The Show Cluster page appears. 2 Enter the fully qualified host name of a server in the Web Server Name field. 3 Click OK. The Cluster Member List page appears. 4 Click the Server Attributes link under Other. The Connect To Server page appears. 5 Select a server to connect to from the Web Server Name drop-down box. 6 Click OK.
Using maintenance mode (Windows only) Putting a ClusterCATS Server in maintenance mode lets you remove a server from an active cluster gracefully, so you can perform necessary updates or maintenance tasks without disrupting your users. Using the instructions in this section, you can take a server offline while allowing users to finish their current sessions.
To put a cluster member in maintenance mode: 1 In ClusterCATS Explorer, select a cluster member to update. 2 Select Configure > Load or right-click a cluster member and select Configure > Load. The Properties dialog box appears for the selected cluster member with the Load tab active: 3 Change the peak load threshold to 0% so any additional HTTP requests will be redirected to other servers in the cluster. 4 Click OK.
6 Click the BT Service Status button to display the Manage ClusterCATS Services dialog box: 7 Select the Stopped option to stop the ClusterCATS service, and enter a value, in minutes, in the Drain Down Period field. This option allows current users to conclude their sessions within the time indicated. 8 Click OK. When the drain-down period expires, the server fails over to another server in the cluster.
Updating a cluster member (Windows only) Periodically you will need to update software or content that resides on your cluster members. Software updates include new versions or patches of operating system software, web server software, new web applications, ClusterCATS software, or other third-party products. ClusterCATS lets you put an active cluster member in maintenance mode and then bring it online slowly so you can verify that your changes do not introduce new problems.
8 To initially limit the amount of HTTP traffic sent to the server, return to ClusterCATS Explorer and reconfigure the cluster member’s peak load threshold to a low value such as 10%. 9 Click OK. 10 In ClusterCATS Explorer, right-click a cluster member and select Monitor > Load. The Server Load monitor appears: 11 Observe your cluster member at low usage levels until you are satisfied that your new changes are working properly.
Resetting cluster members ClusterCATS includes a utility for resetting cluster members to their preclustered state. You may want to do this for two reasons: • To permanently remove a cluster member from a cluster • To change a cluster member from one cluster to another To perform these tasks, you must first reset each server’s configuration to its original, preclustered state.
CHAPTER 6 ClusterCATS Utilities ClusterCATS ships with scriptable command-line utilities for configuring, administering, and troubleshooting ClusterCATS clusters. This chapter describes these utilities. Contents • Using btadmin..................................................................................................... 122 • Using bt-start-server and bt-stop-server (UNIX only) .......................................... 125 • Using btcfgchk ...........................................................
Using btadmin is a scriptable utility installed on each server in a cluster. It provides most of the functionality of the Windows-based ClusterCATS Server Administrator so UNIX and Windows administrators can include calls in automated scripts. btadmin This section describes the following: • “Using btadmin on Windows” on page 122 • “Using btadmin on UNIX” on page 122 Using btadmin on Windows is a Windows executable invoked from the command line in the /program directory.
The following sections describe each of these options. [start | stop | restart ] You can start, stop and restart the following daemons with btadmin: Daemon Description appmgr Application manager daemon. dfp Cisco LocalDirector’s Dynamic Feedback Protocol daemon. failover Failover daemon. ipaliasd ClusterCATS failover daemon. ns-httpd HTTP daemon. reqmgr Solaris-only authentication daemon. teserver ClusterCATS Server process on Apache. This option is an alias for teserver_apache.
You can enable, disable, and configure the following ClusterCATS options using the btadmin utility: Option Description btcats Configures the ClusterCATS Server. dfp Configures Cisco LocalDirector’s Dynamic Feedback Protocol. failover Configures the ClusterCATS failover (ipaliasd) support. load Configures the load-balancing preferences. wsroot Configures a web server root directory in case you upgrade your installation or move the root directory. wsprobe Configures the web server probes.
Using bt-start-server and bt-stop-server (UNIX only) The bt-start-server and bt-stop-server utilities start and stop the web server that is bound to the ClusterCATS Server. This command starts or stops either the Netscape Enterprise Server or Apache Web Server.
Using btcfgchk The btcfgchk utility is a network management tool that displays information about your IP and DNS configurations. Use it to analyze and troubleshoot the servers and network. Syntax Invoke btcfgchk from the command line in the / directory using the following syntax: btcfgchk Sample output The following sample output shows how btcfgchk displays configuration information for a system with one network adapter and two IP addresses: btcfgchk FQHN is hartford.brighttiger.
(PRT record) translates an IP address to its host name. ClusterCATS expects the mapping to be one-to-one (one host name to one IP address). Error Description Host name does not map to a single IP address The main host name for this system is not mapping to one IP address. Possible problems are: • The main host name of the system could not be resolved to an IP address. Your fully qualified host name is the combination of the host name and the domain name.
Error Description Host name not found in For each IP address found on the system, an attempt was made to find the corresponding host name. None of the IP addresses any reverse mapping on the system reverse mapped to the system's main fully qualified Probable forward host name. The problem is either: mapping misconfiguration for • The host name maps to the wrong IP address. • The IP address that the host name maps to does not have an entry in the DNS table for the reverse map.
Using hostinfo The hostinfo utility is a network management tool that displays information about a domain name. Use it to analyze and troubleshoot problems with DNS mappings to a domain. Syntax Invoke hostinfo from the command line in the / directory using the following syntax: hostinfo [fully_qualified_host_name] Specifying a fully qualified host name is optional. If you do not specify one, then hostinfo returns information about the current host.
Using sniff The sniff utility is a network management tool that displays the packets that a specific network interface card (NIC) is hearing.
CHAPTER 7 Optimizing ClusterCATS ClusterCATS provides enhanced capabilities that let you customize your ClusterCATS implementation. This chapter describes some of these options. Contents • ClusterCATS dynamic IP addressing (Windows only) ......................................... 132 • Using server failover............................................................................................. 137 • Configuring load-balancing metrics .....................................................................
ClusterCATS dynamic IP addressing (Windows only) This section describes how to enable ClusterCATS dynamic IP addressing on your site. You do not have to configure your system on UNIX for dynamic IP addressing, because it is set up by default.
Benefits of ClusterCATS dynamic IP addressing There are several benefits to your using ClusterCATS dynamic IP addressing: • Using maintenance mode — with dynamic IP addressing, cluster members put into maintenance mode on Windows clusters will fail over to another server and then gracefully return when brought out of maintenance mode. For more information, see “Using maintenance mode (Windows only)” on page 115.
5 Open the Advanced IP Addressing dialog box by right-clicking Network Neighborhood. Select Properties. On the Protocols tab, select TCP/IP Protocol and click Properties and then click Advanced. 6 Select the computer’s primary NIC in the Adapter field. Add the new IP address in the IP Addresses region. You will use this address as the maintenance address and machine address. Make a note of all IP addresses on the NIC. 7 Click OK, and OK again and click the Identification tab. Click Change.
12 Reinstall products that are configured as part of IIS, including JRun/ColdFusion and ClusterCATS. This should include any products you uninstalled in step 3. When you install ClusterCATS, you must select the "Server Failover" option during the installation procedure. Note: Do not create any clusters at this time. 13 Enable the ClusterCATS dynamic IP addressing scheme using the procedure described in “Enabling ClusterCATS dynamic IP addressing” on page 135.
6 Open the Advanced IP Addressing dialog box by right-clicking Network Neighborhood, and select Properties. On the Protocols tab, select TCP/IP Protocol and click Properties. Click Advanced. 7 Unbind the IP addresses from the web server’s NIC by selecting each IP address in the IP Addresses region and clicking Remove. This step removes the IP addresses corresponding to the website. 8 Click OK, three times. 9 Restart all the systems in the cluster.
Using server failover The ability to fail over servers that have become unavailable to redundant servers is a cornerstone of any mission-critical application, one that ensures continuous, reliable operation. Server failover is an option to select during installation. If you did not select it, you must reinstall ClusterCATS to enable it.
Configuring load-balancing metrics You have the option to customize the load-balancing metrics of web servers clustered with ClusterCATS software. This section describes how to customize metrics to your specific website implementation. Overview of metrics The JRun and ColdFusion servers record how long it takes to process each request, and can return metrics derived from this data, upon request.
Load types The page ClusterCATS probes for load-balancing options, getsimpleload.jsp for JRun and getsimpleload.cfm for ColdFusion, is located in /btauxdir. The probe agent responds to output generated by this page and uses it to calculate the overall load, based on the weighting of the metrics set in the LOADTYPE variable: • AVG_REQ_TIME — calculates load based on the average service request time. The load is derived by dividing the request time by the maximum acceptable request time.
Troubleshooting the load-balancing metrics If ClusterCATS gets an exception every time it processes getsimpleload.jsp, you may have installed ClusterCATS before installing JRun. In this case, verify that the following is true: • JRunMetricThread.class file is located in /jrun/lib/ext • The virtual directory /btauxdir is configured on your web server. (This was created during installation, but you might have removed it.
INDEX A A records 19 absolute hyperlinks 72 active mode 110 active/passive mode changing 111 changing in UNIX 112 changing in Windows 111 adding cluster members UNIX 64 Windows 63 Admin Agent 62 Admin Manager 62 administering ClusterCATS alarm notifications 98 Apache considerations 50 btadmin 53, 122 bt-start-server 125 bt-stop-server 125 ClusterCATS Explorer 48 ClusterCATS Web Explorer 49 e-mail support options 100 introduction 48 Netscape considerations 50 opening the Web Explorer 51 scripting 122 secur
load thresholds 66 maintenance mode 115 maintenance support 60 moving to cluster 120 peak load threshold 66 preclustered state 120 probes and monitors 77, 84 removing (UNIX) 65 removing (Windows) 65 restricting 113 updating 118 Cluster Setup Wizard 54 ClusterCATS administration 53 ClusterCATS components btadmin 53 Explorer 48 overview 6 Server 48 Server Administrator 52 Web Explorer 49 ClusterCATS Explorer defined 48 icon legend 49 interface 49 ClusterCATS Server Administrator 52 ClusterCATS Server, defined
optimizing with dynamic IP addressing 133 parallel servers 26 persistent sessions 74 static vs. dynamic IP addressing 137 systems monitoring 26 Web server alarm notification 98 failures alarm notifications 98 common 24 disk 98 HTTP server 98 probes 98 server busy 98 server unreachable 98 web server failover 98 firewalls before you install 38 configuring 38 port 9123 39 port 9129 39 scalability 16 forward DNS entries 37 G getsimpleload.
monitoring load status 68 monitors 77, 84 adding new 78, 85 removing in Windows 81, 88 N name servers 19 Netscape, Web Explorer considerations 50 NT domain authentication 105 O optimizing server failover 133 P parallel servers 26 passive mode 110 passive mode, LocalDirector 92 peak load threshold 66 performance, scalability 10 persistent session failover 74 PREV_REQ_TIME 139 primary DNS server 34 probe monitors adding 78 probe monitors, adding 85 probes 77, 84 adding in UNIX 81, 89 adding in Windows 77
sniff sample output 130 syntax 130 using 130 software-based clustering advantages 31 considerations 31 solutions 30 state management 13 static vs.
146 Index
