Dificultades al conjugar el control as´ıncrono con paradigmas bien establecidos

Do not add this mount information to the/etc/fstabfile because only the cluster software can mount and unmount file systems used in a service.

4. Copy all the required files to the document root directory.

5. If you have CGI files or other files that must be in different directories or in separate partitions, repeat these steps, as needed.

7.3. Installing and Configuring the Apache HTTP Server

The Apache HTTP Server must be installed and configured on all members in the assigned failover domain, if used, or in the cluster. The basic server configuration must be the same on all members on which it runs for the service to fail over correctly. The following example shows a basic Apache HTTP Server installation that includes no third-party modules or performance tuning.

On all member systems in the cluster (or members in the failover domain, if used), install thehttpd RPM package. For example:

rpm -Uvh httpd-# version$ .# arch$ .rpm On one system, perform the following tasks:

1. Edit the/etc/httpd/conf/httpd.confconfiguration file and customize the file according to your configuration. For example:

• Specify the directory that contains the HTML files. Also specify this mount point when adding the service to the cluster configuration. It is only required to change this field if the mountpoint for the website’s content differs from the default setting of/var/www/html/. For example:

DocumentRoot "/mnt/httpdservice/html"

• If the script directory resides in a non-standard location, specify the directory that contains the CGI programs. For example:

ScriptAlias /cgi-bin/ "/mnt/httpdservice/cgi-bin/"

• Specify the path that was used in the previous step, and set the access permissions to default to that directory. For example:

# Directory /mnt/httpdservice/cgi-bin"$

AllowOverride None Options None Order allow,deny Allow from all

# /Directory$

Additional changes may need to be made to tune the Apache HTTP Server or add module functionality. For information on setting up other options, refer to theRed Hat Enterprise Linux System Administration Guideand theRed Hat Enterprise Linux Reference Guide. 2. The standard Apache HTTP Server start script,/etc/rc.d/init.d/httpdis also used within

the cluster framework to start and stop the Apache HTTP Server on the active cluster member. Accordingly, when configuring the service, specify this script in theUser Scriptfield of the

Servicedialog box.

3. Copy the configuration file over to the other members of the cluster (or members of the failover domain, if configured).

Before the service is added to the cluster configuration, ensure that the Apache HTTP Server direc- tories are not mounted. Then, on one member, invoke theCluster Configuration Toolto add the service, as follows. This example assumes a failover domain namedhttpd-domainwas created for

Chapter 7. Setting Up Apache HTTP Server 95

this service. Figure 7-1 shows the% device& settings for configuring the shared storage and mount point where HTML files and CGI scripts will be stored.

Figure 7-1. Configuring Apache HTTP Server

1. Select theServicestab and clickNew. TheServiceproperties dialog box is displayed. a. Give the service a name (for example,httpd).

b. Choosehttpd-domainfrom theFailover Domainlist. c. Specify a value in theCheck Intervalfield.

d. Specify/etc/rc.d/init.d/httpdin theUser Scriptfield. e. ClickOK.

2. Select thehttpdservice on theServicestab and clickAdd Child. TheAdd Device or Service IP Addressdialog box is displayed.

a. ChooseAdd Deviceand clickOK. TheDeviceproperties dialog box is displayed. b. Enter the device special file name in the Device Special File field (for example,

/dev/hda7).

c. Enter the mount point in theMount Pointfield (for example,/var/www/html/). d. Chooseext3from theFS Typelist.

e. Enterrwin theOptionsfield.

f. Ensure thatForce Unmountis checked, and clickOK.

3. Ensure that thehttpdservice is still selected in theServicestab and clickAdd Child. TheAdd

Device or Service IP Addressdialog box is displayed.

a. ChooseAdd Service IP Addressand clickOK. TheService IP Addressproperties dia- log box is displayed.

b. In theIP Addressfield, specify an IP address, which the cluster infrastructure binds to the network interface on the cluster system that runs thehttpdservice (for example, 192.168.26.10).

c. Specify a netmask ofNonein theNetmaskfield.

d. In theBroadcastfield, specify an IP address ofNonefor broadcasting on the cluster subnet.

96 Chapter 7. Setting Up Apache HTTP Server

4. ChooseFile=>Saveto save your changes.

5. To start the Apache HTTP Server within theCluster Status Tool, highlight the service and click

Chapter 8.

Cluster Administration

This chapter describes the various administrative tasks involved in maintaining a cluster after it has been installed and configured.

8.1. Overview of the Cluster Status Tool

TheCluster Status Tooldisplays the status of the cluster service, cluster members, and application services, and shows statistics concerning service operation.

The cluster configuration file (maintained by theCluster Configuration Tool) is used to determine how to manage the members, services, and cluster daemons.

Important

Do not manually edit the cluster configuration file.

Use theCluster Status Toolto start and stop the cluster service on that particular member, restart application services, or move an application service to another member.

TheCluster Configuration Toolcan be displayed by choosingCluster=>Configurewithin the

Cluster Status Tool.

Figure 8-1. Cluster Status Tool

8.2. Displaying Cluster and Service Status

Monitoring cluster and application service status can help identify and resolve problems in the cluster environment. The following tools assist in displaying cluster status information:

In document Estudio de estrategias de control PID basado en eventos para la implementación de controles embebidos (página 35-38)