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CHAPTER 2

Scalability and Availability Overview

This chapter describes the concepts involved in achieving scalable and highly available
web applications.

Contents

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What is scalability? ................................................................................................ 10

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Successful scalability implementations ................................................................... 13

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What is website availability?................................................................................... 23

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Creating scalable and highly available sites............................................................. 28

Содержание ClusterCATS

Страница 1: ...macromedia Using ClusterCATS ...

Страница 2: ...names of Macromedia Inc or other entities and may be registered in certain jurisdictions including internationally This product includes code licensed from RSA Data Security This guide contains links to third party websites that are not under the control of Macromedia and Macromedia is not responsible for the content on any linked site If you access a third party website mentioned in this guide th...

Страница 3: ...ity 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 availabi...

Страница 4: ...eating 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 sess...

Страница 5: ...s 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 ...

Страница 6: ...rCATS 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 ...

Страница 7: ...ibes 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 ...

Страница 8: ... 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...

Страница 9: ...t 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 macromed...

Страница 10: ...5 626 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 com store ...

Страница 11: ...ment 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 p...

Страница 12: ... 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 sh...

Страница 13: ...r 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 Cl...

Страница 14: ...pecific 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 an...

Страница 15: ...erprise 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...

Страница 16: ...S 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 cluster...

Страница 17: ...tions 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...

Страница 18: ...rCATS 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 o...

Страница 19: ...s 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 ...

Страница 20: ...nce 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 loggin...

Страница 21: ...rs to scale linearly relative to constraining resources For example when a processor is added to a single processor server the operating system incurs extra overhead in synchronizing threads and resources across processors to provide symmetric multiprocessing Part of the additional processing power that the second processor provides is used by the operating system to manage the additional processo...

Страница 22: ... round robin Internet DNS or third party clustering packages Hardware and software combinations Each option has distinct merits Most load balancing solutions today manage traffic based on IP packet flow This approach effectively handles non application centric sites However to effectively manage web application traffic you must implement a mechanism that monitors and balances load based on specifi...

Страница 23: ...partitioning on page 15 Application session and state management As you create web applications you will probably create specific variables that you intend to carry across multiple interactions between a user s browser and a site s web server s Using client variables that are stored in a shared state repository or session variables that are stored in memory of a specific server are popular approac...

Страница 24: ...uman Resources web application on a company intranet The HR Generalist adds two new employee records to the HR database by filling out a web form because two new employees have been hired The Generalist enters most of the vital information into the records but doesn t yet have the new employees phone extensions or HMO selections so leaves those fields blank Later in the day the HR Generalist s man...

Страница 25: ...ns An example of a business service is an algorithm that automatically calculates shipping and handling charges for an order based on the total cost of the order In JRun this logic is contained within scriptlets and EJBs In ColdFusion this logic is contained in ColdFusion pages Depending on the nature of the business and how often the business rules change business logic can be partitioned to resi...

Страница 26: ... perform poorly Instituting industry best practices such as coding standards design reviews and code walkthroughs can significantly help to alleviate this problem Processor capacity even a well architected and programmed web application can perform poorly if the web server s CPU is unable to provide sufficient processing power Ensure that heavy load mission critical applications reside on hardware...

Страница 27: ...ices on a TCP IP network that allows network users to use hierarchical natural language names rather than computer IP addresses when searching for computer hosts servers on a network DNS is used extensively on the Internet and on private enterprise networks including LANs and WANs The primary capability of DNS is its ability to map host names to IP addresses and vice versa For example suppose the ...

Страница 28: ... your web applications are to work well with DNS Zones and domains on page 18 DNS record types server aliases and round robin distribution on page 19 Zones and domains A Domain Name System is composed of a distributed database of names The names in the DNS database establish a logical tree structure called the domain name space On the Internet the root of the DNS database is managed by the Interne...

Страница 29: ... address mapping where the natural language name is the primary name representing the IP address PTR Record contains the IP address to host name mapping This is the reverse lookup of the A record in which given the IP address the natural language host name for the IP address is displayed CNAME Record short for canonical record This record contains an alias name that maps to the primary host name o...

Страница 30: ...to perform load testing Load testing is important to your website s success because it lets you test its capacities before you deploy it so you can find and fix problems before they are exposed to your users Determining your site s purpose and the amount of traffic you anticipate may affect how you load test it Managers of small sites who don t expect heavy concurrent loads might be able to organi...

Страница 31: ...ls on the market including Segue s SilkPerformer Mercury Interactive s LoadRunner and RSW s e LOAD Each of these packages provides substantial Web enabled software testing solutions that help you effectively simulate and test load After you purchase install and learn to use load testing software you determine benchmarks that you want to or must achieve for your website to ensure a good user experi...

Страница 32: ...why they occur The number of possibilities would be too large Minimize distributed environment load testing load testing in a distributed environment can be problematic if the network on which you perform load tests becomes congested resulting in poor response times Also if everyone else in the organization uses the network for their everyday activities such as e mail source control and file manag...

Страница 33: ...gruntled customers who will look to your competitors for goods and services This section defines and describes website availability and failover Availability and reliability on page 23 Common failures on page 24 Website availability scenario on page 25 Failover considerations on page 25 Availability and reliability In simple terms availability and reliability mean that you can access a website by ...

Страница 34: ...s common than software failures hardware failures do occur and can include crashed hard drives blown processors and corrupted network cards Diagnosing and fixing these issues can be a lengthy endeavor because of time spent getting parts and performing labor If your web application is mission critical you should ensure a sound hardware redundancy strategy to avoid costly downtime A sound strategy i...

Страница 35: ... causing you to lose significant business Although the application provided many useful features and capabilities customers could not access them because the site s performance degraded to the point that the site became unavailable Because the site was deployed on only one server the incoming traffic could not be load balanced Also without redundant servers in place the site could not intelligentl...

Страница 36: ...ions Unlike the primary backup scheme the multiple servers in a parallel scheme are considered peers and are grouped as a single entity to support one or more applications You can use identical cloned hardware in your server clusters or you can mix hardware sizes and models Cloned higher capacity higher end hardware might have greater up front hardware costs but help minimize long term administrat...

Страница 37: ...agers real time Web based alerts and so on to the appropriate administrator for prompt attention Besides notifying the administrator that a problem has occurred you also want your failover solution to automatically redirect traffic intended for the unavailable server to other available servers until the unavailable server is fixed This crucial corrective action is what keeps your website up and av...

Страница 38: ... for a website Clustering for scalability works by distributing load among servers in the cluster load balancing using an unintelligent but regular distribution sequence round robin DNS and routers or a predefined threshold or algorithm specialized clustering software that you specify and can adjust for each server in the cluster Clustering for failover relies on redundant servers to ensure that b...

Страница 39: ...onsidered semi intelligent devices because they can detect a server failure and redirect requests to other servers If a web server fails or stops responding the router stops sending packets to the unresponsive server Routers are not considered fully intelligent because while they can redirect requests upon discovering a failure they do not let you configure redirection thresholds for individual se...

Страница 40: ... server in a cluster so it cannot effectively manage load to prevent failures Software based clustering solutions There are several kinds of software based clustering solutions on the market As with hardware based clustering solutions there are strengths and weaknesses associated with each These software solutions include Round robin DNS a very popular choice because of its relative simplicity and...

Страница 41: ... servers in the cluster No single point of failure by distributing the load balancing and failover capabilities among multiple servers in a cluster or multiple clusters as opposed to relying on only a single device no individual server failure can disable your application Considerations Consider the following issues when evaluating software based solutions for your environment Differences among fe...

Страница 42: ...or more comprehensive coverage Having the flexibility to integrate hardware with software means that your organization won t necessarily have to absorb a capital loss on a previous technology investment if you decide to purchase additional clustering technology However as already discussed all hardware or software solutions are not equal Many have different features and capabilities and not all ha...

Страница 43: ...e 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 34 Installing ClusterCATS 41 After you install 45 ...

Страница 44: ... forward lookup host name to address translation and reverse lookup address to host name translation be registered with your DNS server For evaluation purposes you can use host files but this is not recommended in a production environment Note ClusterCATS does not support Dynamic Host Configuration Protocol DHCP A unique IP address must be assigned to each web server This section addresses the fol...

Страница 45: ...l DNS server s table However if a user enters a URL for a site that the browser on that computer has never visited the local DNS server must access the primary DNS server on the Internet to resolve the name to IP mapping before the browser can send a request to the appropriate web server To summarize primary and local DNS servers work together to resolve name to IP address mappings in the followin...

Страница 46: ...t requests a name translation Round robin DNS and ClusterCATS work well together You should not rely on just round robin DNS for distributing load for your business critical sites because DNS functionality is limited In short DNS is a good load distribution technique but it cannot manage load because it cannot react to increases in server traffic It also cannot detect server failures nor redirect ...

Страница 47: ...ates effectively with round robin DNS For example for a single location server cluster consisting of four servers you must configure round robin DNS across all four servers for the domain name and individual IP addresses for each explicit server name For example the DNS table forward entries on your primary DNS server would be similar to these The DNS table reverse entries on your primary DNS serv...

Страница 48: ...em Windows If your IP address for the local system is the same as the IP of your web server setting up your site for ClusterCATS dynamic IP addressing can involve reinstalling your web server software and resetting your TCP IP settings Consider this carefully before installing ClusterCATS For more information see ClusterCATS dynamic IP addressing Windows only on page 132 UNIX It is not necessary t...

Страница 49: ...cation in a distributed setting and server to client communication Note You must open both ports on all affected firewalls These ports include the following Port 9123 for TCP and UDP access opening port 9123 on a firewall allows multiple distributed server clusters residing in different locations to communicate with one another across firewalls Port 9129 for TCP and UDP access opening port 9129 on...

Страница 50: ...tication 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 ...

Страница 51: ...S setup exe file from Windows Explorer or the Run dialog box 2 Accept the default installation directory or click Browse to select a different directory and click Next In this manual the installation directory is referred to as CC_install_directory 3 Use the following table to determine which components to install For more information see ClusterCATS components on page 6 If more than one of the su...

Страница 52: ... The names types and install directories of the web servers you will be clustering The directory where JRun is installed Note The procedures in this section assume you have installed JRun ClusterCATS supports the Apache Web Server and the Netscape Enterprise Server on Solaris platforms and the Apache Web Server on Linux For more information about installation options enter at any prompt during the...

Страница 53: ...e config file Enter Apache installation directory usr local apache Enter location of Apache config file httpd conf usr local apache conf Netscape You are prompted to enter the location of Netscape s root directory Enter Netscape Enterprise Server Root usr netscape suitespot https server 6 Enter the configuration file location ClusterCATS prompts you to optimize load balancing for this server Optim...

Страница 54: ...etscape 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 If you entered subset you are prompted to enter a list of the ClusterCATS Server Members that are allowed to fail over to this server For more information see the on...

Страница 55: ...vent the server from reaching the peak threshold For more information see Server load thresholds on page 66 Email addresses for alarm recipients ClusterCATS generates alarm notifications for several events including HTTP server failures low disk space server busy and web server failover You provide e mail addresses of all administrators for ClusterCATS to notify for each generated alarm notificati...

Страница 56: ...46 Chapter 3 Installing ClusterCATS ...

Страница 57: ...ClusterCATS Administration 48 Creating clusters 54 Removing clusters 62 Adding cluster members 63 Removing cluster members 65 Server load thresholds 66 Session aware load balancing 72 Persistent session failover in JRun 74 Using ColdFusion probes 77 Using JRun probes 84 Load balancing devices 92 Administrator alarm notifications 98 Administrator e mail options 100 Administering security 103 ...

Страница 58: ...er is the heart of the clustering and load balancing of ClusterCATS It must be installed on each server in your cluster The server monitors the status of all other web servers in a cluster and tracks application and transaction resource availability ClusterCATS Server runs on Windows Sun Solaris and Linux platforms To administer the ClusterCATS Server use the ClusterCATS Server Administrator Windo...

Страница 59: ...guration clusters servers monitors and probes is represented by a unique icon You can manipulate the icons in much the same manner as you expand and collapse directory trees in the Windows Explorer For a list of which icons represent which objects in the ClusterCATS Explorer click the Icon Legend button ClusterCATS Web Explorer UNIX only You use the ClusterCATS Web Explorer btweb for administering...

Страница 60: ...n a port other than 80 and password protect access to it Netscape considerations By default Netscape Enterprise Server assigns your web server a random six digit communication port number You can either use this assigned number or change it to something easier to remember like port 81 If you are not familiar with configuring your web server s communications ports see the Netscape Enterprise Server...

Страница 61: ... To open the Web Explorer 1 Open a web browser 2 Enter the following URL in the browser s address field For Netscape Enterprise Server v3 x http server name admin port admin serv btweb default html For Netscape Enterprise Server v4 0x http server name admin port https admserv btweb default html For Apache http virtual_host admin port default html servername or virtual_host is the name of the web s...

Страница 62: ... from each server in your cluster The Server Administrator lets you Change installation settings Add and remove the ClusterCATS filter from the web server service Stop and start the ClusterCATS service Reset a clustered server s configuration to its preclustered state The ClusterCATS Server Administrator lets you accomplish these tasks using an easy to use graphical user interface To open the Clus...

Страница 63: ...e ClusterCATS Web Explorer which lets you administer your entire cluster from one central computer you must use btadmin from each server in your cluster btadmin lets you Add and remove the ClusterCATS filter from the web server service Stop and start the ClusterCATS service Place a cluster member in maintenance mode Reset a clustered server s configuration to its preclustered state For more inform...

Страница 64: ...up Wizard This section describes how to create clusters in both ways Creating clusters with the Cluster Setup Wizard on page 54 Manually creating clusters on page 59 Creating clusters with the Cluster Setup Wizard The ClusterCATS Explorer includes the Cluster Setup Wizard that makes creating and configuring clusters easy The wizard steps you through the required definition and configuration steps ...

Страница 65: ...er 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 The List of Web Servers in the Cluster dialog box appears ...

Страница 66: ...set the maintenance support option only when creating a cluster or adding a cluster member to a cluster You cannot configure or modify this option after you have created and added the cluster member to the cluster Enabling maintenance support for clusters requires that you configure your cluster for ClusterCATS dynamic IP addressing For more information see ClusterCATS dynamic IP addressing Window...

Страница 67: ... Click Next The Alert Notification dialog box appears 13 Enter the name of your outbound SMTP mail server in the SMTP mail server field and the e mail address for a recipient of cluster alerts in the E mail addresses field If multiple people will receive different alerts for different types of notification events go to step 14 Otherwise click Next and proceed to step 16 14 To configure different t...

Страница 68: ...rts 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 The Load Balancing Device dialog box appears 17 If you use a hardware based load balancing device in addition to ClusterCATS to manage and distribute load enter the name of the website that this device supports for example ...

Страница 69: ... a new cluster using the fields as described in the following table Field Description Cluster Name 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 creat...

Страница 70: ...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 You can set the maintenance support option only when creating a cluster or adding a cluster member to a ...

Страница 71: ...es 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 The first server that you add to a cluster is known as the Admin Mana...

Страница 72: ...luster icon and select Configure Administration The cluster s Properties dialog box opens displaying the Administration tab The server designated as the Admin Manager is the active entry in the drop down list To determine which server is the Admin Agent in UNIX 1 In the ClusterCATS Web Explorer click the Show Cluster link 2 Enter the fully qualified host name of a server in the Web Server Name fie...

Страница 73: ...ame field enter the fully qualified host name of the web server for example doc macromedia com 4 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 web server for offline maintenance support go to step 6 Note You can set the maintenance support option only when creati...

Страница 74: ...bers 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 ...

Страница 75: ...ht click the server name and select Delete The selected cluster member is deleted from the cluster you selected Removing cluster members in UNIX Use the ClusterCATS Web Explorer to remove cluster members To remove a cluster member from a cluster 1 In the ClusterCATS Web Explorer click the Delete Server link The Delete Server page appears 2 Select a cluster member to delete from the Web Server Name...

Страница 76: ...le Gradual redirection threshold the point at which HTTP requests begin to be redirected to other less loaded members in a cluster so the server s performance does not degrade or become unavailable By default the peak load threshold is 90 and the gradual redirection threshold is 10 These default settings adequately handle HTTP traffic going across most websites However if your website is particula...

Страница 77: ...he 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 ...

Страница 78: ...you selected The load monitor shows three lines Top line red Peak load threshold Middle line yellow Gradual Redirection load threshold Bottom line green JRun ColdFusion server load Adjusting load threshold settings graphically You can view and set threshold settings of a cluster member using the Server Load Monitor s visual display To set or change threshold settings use the mouse to drag the Peak...

Страница 79: ...radual 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 Configuring load thresholds on UNIX To configure load thresholds for a cluster member 1 In the ClusterCATS Web Explorer click the Show Cluster link The Show Cluster page appears 2 Enter the fully qualified host name of...

Страница 80: ... an Error Server cluster_member_name 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 ...

Страница 81: ...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 This value must be lower than the standard load threshold 11 Click OK to apply your new load threshold set...

Страница 82: ...load balancing guarantees that users will not get bumped from the server on which they start their session until the session is complete regardless of the load thresholds that have been defined for that server Note Session aware load balancing may not work if you use absolute hyperlinks in your web pages Absolute links route the HTTP request back to the cluster entry point and redirect according t...

Страница 83: ... 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 ...

Страница 84: ...th the ClusterCATS session aware load balancing feature This ensures that multiple servers do not have concurrent access to the same session data For more information see Session aware load balancing on page 72 A repository used for persistent session data must be shared among the JRun servers in a cluster For information see Using shared files for session swapping on page 75 For an example of usi...

Страница 85: ...t all 7 Repeat this procedure for every server in the cluster Using shared files for session swapping To use file swapping the JRun server s local properties file should contain the following properties session persistence service file session persistence file class allaire jrun session FileSessionStorage See the following paragraph for more on this property session persistence file path mnt myoth...

Страница 86: ...ion persistence jdbc JDBCConnectionURL jdbc odbc JRunSessions session persistence jdbc JDBCSessionTable sessions session persistence jdbc JDBCSessionIDColumn id session persistence jdbc JDBCSessionDataColumn data JDBC swapping requires that you have a valid JDBC driver that can successfully connect to the database You must create a table in your database with an id column and a data column This ex...

Страница 87: ...fied string in the page accessed ClusterCATS restricts that server and redirects requests to other available servers in the cluster ClusterCATS continues to test the restricted server when the probe returns a valid value the server is considered available If a ColdFusion server hangs or fails ClusterCATS attempts to recover the failed service When the service is recovered the probe can restart the...

Страница 88: ...sterCATS 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 The monitor s Properties dialog box appears ...

Страница 89: ...actual URL of the site you want the probe to access and replace success string with a text string that appears on a page on the site you are probing Tips Be sure to include a space between the URL and the success string that you specify The success string must be enclosed in quotation marks Do not modify the RESTART explicit parameter if you want the probe to automatically restart the ColdFusion S...

Страница 90: ... 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 For probes that do not restart the web application the Frequency depends on how long you can reasonably afford to have your web ...

Страница 91: ...uring ColdFusion probes in UNIX This section describes the following Adding ColdFusion probes on page 81 Editing and removing ColdFusion probes on page 83 Adding ColdFusion probes To add a new 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 In the Web Server Name field enter the fully qualified host name o...

Страница 92: ... probe to automatically restart the ColdFusion Server upon detecting a failure However if you do not want ClusterCATS to automatically restart the ColdFusion Server upon detecting a failure replace RESTART with NORESTART Timeout sec Enter a time in seconds to indicate how long ClusterCATS should wait before a ColdFusion server failure is registered Do not set this value to less than 60 seconds bec...

Страница 93: ...robe in the Web Server Name field 4 Click OK The Cluster Member List page appears 5 Click the Server Attributes link The Connect To Server page appears 6 Select the server that hosts the probe in the Web Server Name lis tbox 7 Click OK The selected server s Properties page appears 8 Click the ColdFusion Probe link The Probe List page appears 9 Select the probe to edit or remove 10 To remove the pr...

Страница 94: ...s not return the user specified string in the page accessed ClusterCATS restricts that server and redirects requests to other available servers in the cluster ClusterCATS continues to test the restricted server when he probe returns a valid value the server is considered available If the JRun server hangs or fails ClusterCATS attempts to recover the failed service When the JRun service is recovere...

Страница 95: ...er 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 The monitor s Properties dialog box appears ...

Страница 96: ...LOG URL enter the actual URL of the page you want the probe to test By default this is http your_server btauxdir jrunprobe jsp The probe opens the page and searches for the success_string success_string enter a text string that appears at the page specified by the URL If the success_string includes spaces it must be enclosed in quotation marks RESTART NORESTART enter RESTART to make the probe auto...

Страница 97: ...ect an actual failure on the JRun server 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 This is highly site specific because it depends on system resources available on servers and the volume of traffic at a site For probes that do n...

Страница 98: ...he 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 2 Select the cluster_name Monitor Manager monitor_name probe_name in the left pane 3 Select Probe Delete or right click the probe and select Delete Configuring JRun probes in UNIX This section desc...

Страница 99: ...ber 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 7 Click the JRun Probe link If there are probes for this server the Probe List page appears 8 To create a new probe click New The JRun Application Probe page appears If this is the ...

Страница 100: ...ou want the probe to test By default this is http your_server btauxdir jrunprobe jsp The probe opens the page and searches for the success_string success_string enter a text string that appears at the page specified by the URL If the success_string includes spaces it must be enclosed in quotation marks RESTART NORESTART enter RESTART to make the probe automatically restart the default JRun server ...

Страница 101: ...s the JRun probe 10 To edit the probe click Edit A page with all the available probes appears 11 Edit the fields corresponding to the probe that you want to change and click Register 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...

Страница 102: ...tor using the ClusterCATS Explorer on Windows only Note You must use Cisco LocalDirector Version 3 1 4 software or later Before configuring ClusterCATS with LocalDirector you must configure LocalDirector to manage your web servers For more information see the Cisco documentation LocalDirector considerations Be aware of the following issues when using ClusterCATS with Cisco LocalDirector When load ...

Страница 103: ... installation and configuration Ensure that you have defined an IP address for LocalDirector and that the LocalDirector network interfaces are configured correctly You can use the ping utility to test network connectivity 3 Create a virtual server www yourcompany com in LocalDirector that corresponds to the cluster 4 In LocalDirector bind explicit real servers participating in the cluster with the...

Страница 104: ...luster 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 ...

Страница 105: ...l 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 Update Frequency sec Enter the frequency w...

Страница 106: ...pen 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 The selection in the Load Balancing Product drop down list indicates how ClusterCATS will actively load balance HTTP traffic across the cluster 5 Enter the name of the website in the Web...

Страница 107: ...ith ClusterCATS To integrate ClusterCATS with a third party load balancing device 1 In ClusterCATS Web Explorer click the Show Cluster link 2 Enter the fully qualified host name of a server to integrate with another load balancing product in the Web Server Name field 3 Click OK The Cluster Member List page appears 4 Click the Administration link under Cluster Attributes 5 In the Load Balancing Pro...

Страница 108: ...ATS Explorer select a cluster 2 Select Configure Alarm Notification or right click the cluster and select Configure Alarm Notification The Alarm Notification dialog box displays 3 Select an event for which to trigger an alarm and enter the e mail address of the person you want to receive an e mail notification of the event If you want multiple people to receive an e mail notification about an even...

Страница 109: ...Name field 3 Click OK The Cluster Member List page appears 4 Click the Alarm Notification link The Alarm Notification page appears 5 Enter the e mail address of the person you want to be notified about the occurrence of an event in the event s corresponding field If you want multiple people to receive an e mail notification about one event add more e mail addresses to the field Separate each addre...

Страница 110: ... to Macromedia s Technical Support team that contains basic configuration information about your cluster This information enables Macromedia to provide optimal support by understanding your environment when you call a Technical Support representative Support e mail contains the following information Cluster name and the number of servers the cluster contains Statistics for each server including fa...

Страница 111: ...field 3 Click OK The Cluster Member List page appears 4 Click the Support link The Cluster Support page appears 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 ...

Страница 112: ... 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 Report e mail Enter the e mail address of the person at your organization that should receive daily reports about your clusters If ...

Страница 113: ...cation Windows NT Only you may want to use this security setting if your organization is fairly large and contains many distributed administrator groups that need to access your server clusters To use this setting you must define your global administrators group in the form BT_clustername where clustername is the exact name of the cluster you created with the ClusterCATS Explorer The global admini...

Страница 114: ...rver ClusterCATS Explorer will display user name and password prompts upon each attempt to access the servers from the ClusterCATS Explorer 2 In ClusterCATS Explorer select a cluster 3 Select Configure Administration or Cluster Properties both menu selections display the Properties dialog box or right click the cluster and select Configure Administration The Properties dialog box appears 4 Select ...

Страница 115: ...xist in which NT domain by communicating with any Windows NT domain controller for the domain You can view the list of servers that exist in the Windows NT domain with the Network Neighborhood Windows NT utility If no trust relationship exists then cluster members must be from the same Windows NT domain To enable Windows NT domain authentication 1 Select Start Programs Administrative Tools User Ma...

Страница 116: ... only if security is not a concern for example in a development or QA environment By default ClusterCATS administrator security is disabled However if you have previously configured the security mode for your cluster and now want to turn if off perform the following procedure To disable authentication 1 Open the ClusterCATS Explorer and select a cluster with authentication enabled 2 Select Configu...

Страница 117: ...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 ...

Страница 118: ...108 Chapter 4 Configuring Clusters ...

Страница 119: ...ite 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 110 Changing active passive settings 111 Changing restricted unrestricted settings 113 Using maintenance mode Windows only 115 Updating a cluster member Windows ...

Страница 120: ... balancing and availability In passive state HTTP requests are passed directly to the web server without ClusterCATS Server interception For more information see Changing active passive settings on page 111 Restricted Unrestricted Setting Determines whether active cluster members receive HTTP traffic Restricted ClusterCATS Servers do not receive HTTP traffic Unrestricted ClusterCATS Servers are se...

Страница 121: ...nt to a server that is in the passive state are passed directly to the web server without ClusterCATS Server processing Changing active passive settings in Windows To change a cluster member s state 1 Open the ClusterCATS Explorer and select a cluster member 2 Select Configure State or right click a cluster member and select Configure State The server Properties dialog box appears 3 To make Cluste...

Страница 122: ... 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 The selected server s Properties page appears 7 Click the Administration link The Server Administration page appears for the selected server 8 To make ClusterCATS Server ignore incoming HTTP requests and pass them directly to the web server select Passiv...

Страница 123: ...e 113 Restricting unrestricting servers in UNIX on page 114 Restricting unrestricting servers in Windows To change restriction settings for a cluster member 1 Open the ClusterCATS Explorer and select a cluster member 2 Select Configure State or right click a cluster member and select Configure State The Server Properties dialog box appears 3 Select the Active Member option if the server has been i...

Страница 124: ...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 The selected server s Properties page appears 7 Click the Administration link The Server Administration page appears for the selected server 8 To ensure that HTTP requests sent explicitly to this cluster member are redirected to another server within the cluster sel...

Страница 125: ...nce mode the servers that temporarily assumed the restricted server s IP address and HTTP traffic return the IP address to the affected server so it can receive and process HTTP requests Note Macromedia recommends that you set up your clusters with ClusterCATS dynamic IP addressing for using maintenance mode For more information see Using server failover on page 137 When it is enabled maintenance ...

Страница 126: ...perties 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 5 Physically go to the server you selected in step 1 and open the ClusterCATS Server Administrator on it by selecting Start Programs Macromedia ClusterCATS Server Administrator The Clu...

Страница 127: ...nce mode 1 Physically go to the server and open the ClusterCATS Server Administrator by selecting Start Programs Macromedia ClusterCATS Server Administrator The ClusterCATS Server Administrator appears 2 Click the BT Service Status button to display the Manage ClusterCATS Services dialog box 3 Select the Running option 4 Click OK 5 Open the ClusterCATS Explorer and select a cluster member to take ...

Страница 128: ...he server in maintenance mode using the instructions in Using maintenance mode Windows only on page 115 2 Make your updates to the inactive server 3 Open a web browser on the cluster member and enter the server name associated with the maintenance address defined for the server For example serv1 mycompany com If you configured the maintenance address correctly as described in ClusterCATS dynamic I...

Страница 129: ... 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 12 When you are certain that the updates you made have not adversely affected the server s operation set the peak and gradual redirection load thresholds back...

Страница 130: ...or the following reasons Using ClusterCATS Explorer to delete cluster members from a cluster does not delete the server s ClusterCATS configuration which is stored in the server s registry Running the ClusterCATS uninstall program and reinstalling does not overwrite the server s ClusterCATS configuration To reset a server to its preclustered state 1 Open the ClusterCATS Server Administrator on thi...

Страница 131: ...e 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 126 Using hostinfo 129 Using sniff 130 ...

Страница 132: ...C_install_directory directory If you run btadmin on Red Hat Linux the ksh shell must be installed The syntax for btadmin is btadmin start stop restart daemon btadmin enable disable add delete config option instance btadmin show reset help Option Description btadmin Displays btadmin online help btadmin v Displays the current version of Microsoft s IIS if it is bound to the ClusterCATS Server btadmi...

Страница 133: ...er For Apache web servers enter https hostname 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 On NES the ClusterCATS Ser...

Страница 134: ...reset Use the reset option to reinitialize cluster configuration settings on the current server For more information see Resetting cluster members on page 120 help Use the help option to get a list of the btadmin utility s features and syntax Option Description btcats Configures the ClusterCATS Server dfp Configures Cisco LocalDirector s Dynamic Feedback Protocol failover Configures the ClusterCAT...

Страница 135: ...erver that is bound to the ClusterCATS Server This command starts or stops either the Netscape Enterprise Server or Apache Web Server bt start server and bt stop server are invoked from the command line in the CC_install_directory directory using the following syntax bt start server bt stop server f Use the f option to stop the web server without being prompted for confirmation ...

Страница 136: ...shows how btcfgchk displays configuration information for a system with one network adapter and two IP addresses btcfgchk FQHN is hartford brighttiger com El90x1 PRIMARY hartford brighttiger com 192 168 0 31 255 255 255 0 hartford brighttiger com hartford1 brighttiger com 192 168 0 32 255 255 255 0 hartford1 brighttiger com btcfgchk DNS errors The btcfgchk utility reports on DNS configuration prob...

Страница 137: ...dress Use the ifconfig a command to see information about your adapter Name lookup for hostname failed btcfgchk was not able to determine the IP address for the specified host Your DNS server may be down Use nslookup to see whether it can contact your DNS server IP_address1 reverse maps to hostname which then forward maps to IP_address2 btcfgchk did a lookup on IP_address1 and found a host name to...

Страница 138: ... the system s main fully qualified host name The problem is either 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 Consequently nslookup does not return the hostname Probable round robin configuration for hostname The host name does not map to one IP address Use the hostinfo tool to determine to which ...

Страница 139: ... Sample output The following sample output from the hostinfo utility provides information about a set of round robin DNS host names hostinfo macromedia com Information for host macromedia com FQHN macromedia com Primary Address 0 0 0 0 Domain com Aliases macromedia com www1 macromedia com www2 macromedia com www3 macromedia com Addresses 205 181 25 81 205 181 25 82 205 181 25 83 The hostinfo utili...

Страница 140: ...ess BTBcastAddress BTMcastAddress BTLocalAddress BTSendSize BTRecvSize BTConsole BTLogFile BTSystem Press keys at run time d dump sniff configuration information H display this and more help h display this help l run load balance test thread m run mail test thread p toggle packet dump display q ESC ENTER quit all active threads and exit r run UDP listener thread s run packet test thread x execute ...

Страница 141: ...ovides 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 138 ...

Страница 142: ... your network interface card NIC You must also ensure that the websites static IP addresses that reside on the web server on this computer are removed from the IP stack also with the Network icon in the Control Panel Typically someone added the website IP addresses to the server s IP stack before installing ClusterCATS and creating clusters You must manually remove those IP addresses so ClusterCAT...

Страница 143: ...dresses Setting up a maintenance IP address ensures that you have one static IP address on the system that is not assigned to a web server virtual server or website This address often referred to as the system s maintenance address provides administrators with a consistent way to access the system remotely at all times It also lets ClusterCATS communicate with the server in case of a web server fa...

Страница 144: ...ded Do not change the Domain field on this tab Note The computer name on the Identification tab should only be a NetBIOS name not a fully qualified host name FQHN For example support1 macromedia com is a possible FQHN The first portion of this FQHN support1 can be a NetBIOS name Note that support1 would also appear as the host name under the DNS tab in Protocols The domain under the DNS tab in thi...

Страница 145: ... addressing 1 Verify that you can access your server by its maintenance address If not assign one to the server using the procedure described in Setting up maintenance IP addresses on page 133 2 Configure your web server to support ClusterCATS dynamic IP addressing For Netscape Enterprise Server Verify that the IP addresses associated with the primary web server and hardware virtual servers are co...

Страница 146: ...P 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 ClusterCATS assigns the IP addresses dynamically to your web servers ...

Страница 147: ...at when a server fails its IP address es can be assigned to other servers When the failed over server comes back online ClusterCATS returns the IP addresses to it without conflict On Windows clusters you should use server failover with the ClusterCATS dynamic IP address scheme To configure ClusterCATS dynamic IP addresses the IP address associated with the computer name must be different from the ...

Страница 148: ...he upper threshold of performance at which a server is declared busy for load balancing purposes When a server reaches this critical threshold ClusterCATS redirects further service requests away from the server until it becomes more responsive to its clients ClusterCATS software provides a further enhancement in load balancing options A ClusterCATS agent process probes a special page getsimpleload...

Страница 149: ...enerates three significant output variables that are sent in response to the probe agent s HTTP query CCLOADVALUE the load calculated by getsimpleload jsp getsimpleload cfm using one of the available load metrics The load value identifies how busy the server is as a percentage of its total capacity CCLOADMAX the maximum acceptable time in milliseconds for a request to complete marks the busy thres...

Страница 150: ...e 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 ...

Страница 151: ...ng on UNIX 106 configuring on Windows 103 disabling 106 domain 105 local user 103 NT Domain 105 availability and reliability common failures 24 defined 23 elements of 23 failover considerations 25 sample scenario 25 average request time 138 AVG_REQ_TIME 139 avoiding bottlenecks 16 avoiding double reboot 133 B backup servers 26 before you install 34 configuring DNS 34 domain controllers 40 dynamic ...

Страница 152: ...om port on web server 50 common failures 24 concurrency 14 creating clusters 54 in UNIX 60 in Windows 54 manually 59 Windows 54 with hardware solutions 29 with software solutions 30 D databases concurrency issues 14 locking mechanisms 14 deleting clusters 62 DFP Agent Listen Port 92 DFP hosts 93 DHCP 34 disable mode 106 disabling authentication 106 disk failures 98 DNS before you install 34 btcfgc...

Страница 153: ...ics 138 session aware 72 session aware on UNIX 72 session aware on Windows 72 software based 30 third party devices in UNIX 97 third party devices in Windows 96 using a hardware solution 29 using round robin DNS 30 load levels 68 load management 3 load management method 42 load metrics output variables 139 troubleshooting 140 load monitor 68 load status monitoring 68 load testing available web too...

Страница 154: ...NIX 114 Windows 113 ROUND_TRIP_TIME 139 round robin DNS 30 configuration 37 LocalDirector 92 reverse entries 37 tables example 37 using with ClusterCATS 37 round trip request time 138 routers 92 Cisco LocalDirector 92 load balancing 29 load balancing devices 95 S scalability application partitioning 15 business services 15 common bottlenecks 16 data services 15 databases 17 defined 10 DNS 17 linea...

Страница 155: ...lancing metrics 140 sniff 130 troubleshooting DNS btcfgchk 126 hostinfo 129 U unrestricted mode 110 updating cluster members 118 upgrading servers 115 V virtual servers hardware based clustering 29 W Web applications database locking mechanisms 14 load testing 20 managing state 13 partitioning 15 scalability bottlenecks 16 Web Explorer Apache considerations 50 configuring com port 50 limitations 4...

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