Installing and Configuring HP WebQoS Peak on Linux Edition 1 Manufacturing Part Number: B8306-90001E E0699 U.S.A. © Copyright 1999, Hewlett-Packard Company.
Legal Notices The information in this document is subject to change without notice. Hewlett-Packard makes no warranty of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be held liable for errors contained herein or direct, indirect, special, incidental or consequential damages in connection with the furnishing, performance, or use of this material. Warranty.
Contents 1. HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Viewing the Server Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 What is a Session? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 When Does a Web Server Become Overloaded? . . . . . . . . . . . . . . . . . . .9 How Does WebQoS Peak on Linux Work? . . . . . . . . . . . . . . . . . . . . . . . .
Contents System Resources Sharing Among Virtual Hosts . . . . . . . . . . . . . . . . 26 Global Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 A. HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing History The manual printing date and part number indicate its current edition. The printing date will change when a new edition is printed. Minor changes may be made at reprint without changing the printing date. The manual part number will change when extensive changes are made. Manual updates may be issued between editions to correct errors or document product changes. To ensure that you receive the updated or new editions, you should subscribe to the appropriate product support service.
1 HP WebQoS Peak on Linux This chapter describes the role and benefits of HP WebQoS Peak on Linux and how it fits into your environment.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? provided by your web site. It controls the number and length of sessions admitted to the web server, to ensure that the web server does not become overloaded. It can be installed and configured for the Apache web server. What is HP WebQoS Peak on Linux? HP WebQoS Peak on Linux is a software plug-in (module), which runs inside an HTTP server. The HTTP server currently supported is Apache.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? When Does a Web Server Become Overloaded? A web server becomes overloaded when there are too many requests for the server to fulfill; the server runs out of resources. Requests may be delayed or dropped. For example, a user involved in a long session may experience poor performance or may have to reload a page more than once for it to display.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? redirect the request to another URL, or serve a page with an error message or some helpful information. Arriving Session WebQoS Peak Resources Available? No Deferred Session Yes Resource Information Web Server Completed Session For More Information For more information on HP WebQoS or for frequently asked questions, please refer to: http://www.hp.
2 HP WebQoS Peak on Linux This chapter describes the role and benefits of HP WebQoS Peak on Linux and how it fits into your environment.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? provided by your web site. It controls the number and length of sessions admitted to the web server, to ensure that the web server does not become overloaded. It can be installed and configured for the Apache web server. What is HP WebQoS Peak on Linux? HP WebQoS Peak on Linux is a software plug-in (module), which runs inside an HTTP server. The HTTP server currently supported is Apache.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? When Does a Web Server Become Overloaded? A web server becomes overloaded when there are too many requests for the server to fulfill; the server runs out of resources. Requests may be delayed or dropped. For example, a user involved in a long session may experience poor performance or may have to reload a page more than once for it to display.
HP WebQoS Peak on Linux What is HP WebQoS Peak on Linux? redirect the request to another URL, or serve a page with an error message or some helpful information. Arriving Session WebQoS Peak Resources Available? No Deferred Session Yes Resource Information Web Server Completed Session For More Information For more information on HP WebQoS or for frequently asked questions, please refer to: http://www.hp.
3 HP WebQoS Peak on Linux for the Apache Web Server 15
HP WebQoS Peak on Linux for the Apache Web Server Integrating HP WebQoS Peak on Linux with the Apache Web Server Integrating HP WebQoS Peak on Linux with the Apache Web Server To integrate the WebQoS Peak module with the Apache server, follow the steps under the scenario that best describes your installation: Scenario 1: The Apache server is already installed on the system. 1. Verify that your server has been built with Dynamic Shared Object (DSO) support. a.
HP WebQoS Peak on Linux for the Apache Web Server Integrating HP WebQoS Peak on Linux with the Apache Web Server Scenario 2: The Apache server is not yet installed on the system. Note that this scenario does not apply if you installed from Red Hat. 1. Download and unpack the Apache distribution archive from: http://www.apache.org. 2. Create the directory hpac in apache_dist/src/modules, then find the file mod_hpac.so in /opt/webqos/lib. Copy this file to: apache_dist/src/modules/hpac. 3.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache Configuring WebQoS Peak on Linux for Apache Once the WebQoS Peak module is integrated with the Apache server, admission control becomes operational when the server is (re)started. However, the module's defaults are unlikely to satisfy the needs of all sites. This section describes the configurable parameters of the WebQoS Peak module and how to set these parameters.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache Example 3-1 Sample Output from the top Command 5:03pm up 24 days, 2:38, 10 users, load average: 5.58, 14.68, 17.31 100 processes: 97 sleeping, 3 running, 0 zombie, 0 stopped CPU states: 25.6% user, 34.7% system, 0.0% nice, 39.5% idle Mem: 322616K av, 189580K used, 133036K free, 63580K shrd, 90944K buff Swap: 136512K av, 0K used, 136512K free 59816K cached 2.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache same user agent will start a new session. All privileges that the old session might have enjoyed are lost. Responding to Rejected Sessions If conditions on the web server do not allow servicing new requests, sessions can be redirected or rejected. You turn on redirection indirectly by setting the redirection URL with the HPACRedirectURL directive.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache This is the easiest but least informative way to respond to a rejected request. Users may try to reconnect right away, generating extra load on the system. When the rejectpage rejection policy is in effect, the server returns the contents of a page containing a custom, more explanatory response to the client.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache Monitoring the % Priority Requests and Last Allocation Delay statistics can help in setting a realistic allocation rate. The first statistic will show the system's load due to priority sessions. Reduce the allocation rate if this number approaches, or is over, 50%. The second statistic shows how long the user of a deferred session had to wait before gaining access to the server.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache the newline character on all but the last line. For example, We are sorry, our server is busy. In order \ to ensure adequate levels of service to \ our current visitors, we cannot serve you \ at this time. We have allocated you a \ position in line and will serve you as \ soon as we can. HPACDeferralMessage The third part is the countdown line, which can be set with the HPACDeferralEnterMsg directive.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache HPACStatsLogging on In addition, you can specify the time interval between log updates with the HPACLogUpdateInterval directive. The default for this directive is “300” seconds. You can specify the log file with the HPACStatsLogfile directive. For example, to specify that the log file apache_home/log/stats.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache NOTE The HPACStatsLogging, HPACLogUpdateInterval and HPACStatsLogfile directives set global parameters, therefore they should be used outside virtual host configuration blocks. They are ignored inside the virtual host configuration blocks. A log entry consists of a number of comma separated fields, as follows: 07/Oct/1998:19:30:00,virtual.host.com,15,0,0,0,0,0,0,0,181, 0,0,0.5,0.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache System Resources Sharing Among Virtual Hosts By default, each virtual host equally shares the system resources. However, this does not guarantee equal use of the resources. Virtual hosts hosting active sites may use more than their fair share of system resources, at the expense of other virtual hosts. A more equitable use of system resources can be achieved using one of the techniques described below.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache isolation is turned on with the HPACVHostIsolation directive. The default for this directive is “off.” For example, to turn on virtual host isolation, use the following directive in your configuration file: HPACVHostIsolation on With this option in effect, WebQoS Peak raises the priority of new sessions for those virtual hosts that contribute less than their assigned share to the system load.
HP WebQoS Peak on Linux for the Apache Web Server Configuring WebQoS Peak on Linux for Apache 28 Chapter 3
A HP WebQoS Peak Configurable Parameters 29
HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server HP WebQoS Peak Configurable Parameters for the Apache Web Server You can modify the behavior of the WebQoS Peak modules by placing the appropriate directives (commands) in your Apache configuration file(s): either httpd.conf, srm.conf, or access.conf. These configuration files can be found in apache_home/conf/.
HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server Table A-1 HP AC Configurable Parameters for the Apache Web Server Parameter Argument Default Description HPACDeferralEnterMsg string You will automatically enter the site in Sets the heading for the time counter on the deferral page. HPACDeferralMessage string We are sorry, our server is busy.
HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server Table A-1 HP AC Configurable Parameters for the Apache Web Server Parameter Argument Default Description HPACLoadDamping 0 <= x <= 1.0 (real number) 0.1 Sets the damping factor used to compute the web server load. Note: larger values make the controller more responsive to recent activity.
HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server Table A-1 HP AC Configurable Parameters for the Apache Web Server Parameter Argument Default Description HPACRejectionPolicy defer| reject| rejectpage reject Sets the rejection policy. If the policy is reject (default), users whose requests are rejected will see the message returned by the server for the HTTP_SERVICE_ UNAVAILABLE code.
HP WebQoS Peak Configurable Parameters HP WebQoS Peak Configurable Parameters for the Apache Web Server Table A-1 HP AC Configurable Parameters for the Apache Web Server Parameter Argument Default Description HPACShareUnits n>0 (integer) 1 Sets the number of units of server resources a virtual host is entitled to use. (A unit is calculated as 1.0/total_share_units). This number is used to compute the percentage of the web server's total resources a virtual host is allowed to use.
