2.2. MARCO TEÓRICO REFERENCIAL
2.2.7. CAUSAS DETERMINANTE DE LA UNIÓN DE HECHO
C. The GFS Setup Druid ... 157 D. Supplementary Hardware Information ... 163 E. Supplementary Software Information... 169 F. Cluster Command-line Utilities... 179
Appendix A.
Using Red Hat Cluster Manager with Piranha
A cluster can be used in conjunction with the Piranha load-balancing features to deploy a highly available e-commerce site that has complete data integrity and application availability, in addition to load balancing capabilities.Figure A-1 shows how you could use Red Hat Cluster Manager with Piranha. The figure shows a cluster with a three-tier architecture, where the top tier consists of Piranha load-balancing systems to distribute Web requests. The second tier consists of a set of Web servers to serve the requests. The third tier consists of a cluster to serve data to the Web servers.
Figure A-1. Cluster in an LVS Environment
In a Piranha configuration, client systems issue requests on the World Wide Web. For security reasons, these requests enter a Web site through a firewall, which can be a Linux system serving in that ca- pacity or a dedicated firewall device. For redundancy, you can configure firewall devices in a failover configuration. Behind the firewall are Piranha load-balancing systems, which can be configured in an active-standby mode. The active load-balancing system forwards the requests to a set of Web servers. Each Web server can independently process an HTTP request from a client and send the response back to the client. Piranha enables an administrator to expand a Web site’s capacity by adding Web servers to the load-balancing systems’ set of active Web servers. In addition, if a Web server fails, it can be removed from the set.
This Piranha configuration is particularly suitable if the Web servers serve only static Web content, which consists of small amounts of infrequently changing data, such as corporate logos, that can be easily duplicated on the Web servers. However, this configuration is not suitable if the Web servers serve dynamic content, which consists of information that changes frequently. Dynamic content could
152 Appendix A. Using Red Hat Cluster Manager with Piranha
include a product inventory, purchase orders, or customer database, which must be consistent on all the Web servers to ensure that customers have access to up-to-date and accurate information. To serve dynamic Web content in a Piranha configuration, add a cluster behind the Web servers, as shown in the previous figure. This combination of Piranha and Red Hat Cluster Manager allows for the configuration of a high-integrity, no-single-point-of-failure e-commerce site. The cluster can run a highly-available instance of a database or a set of databases that are network-accessible to the Web servers.
For example, the figure could represent an e-commerce site used for online merchandise ordering through a URL. Client requests to the URL pass through the firewall to the active Piranha load- balancing system, which then forwards the requests to one of the three Web servers. The Red Hat Cluster Manager systems serve dynamic data to the Web servers, which forward the data to the re- questing client system.
Appendix B.
Using Red Hat GFS with Red Hat Cluster Suite
This appendix provides information about considerations to take when running Red Hat GFS 6.0 with Red Hat Cluster Suite and consists of the following sections:• Section B.1Terminology
• Section B.2Changes to Red Hat Cluster • Section B.3Installation Scenarios
B.1. Terminology
You may have encountered new terms associated with Red Hat Cluster Suite. The following list pro- vides a brief description of terms used with Red Hat GFS and Red Hat Cluster Suite:
GFS Setup Druid
This application is a Red Hat Cluster GUI for initial configuration of Red Hat GFS. The GUI is launched separately from the Red Hat Cluster GUI, theCluster Configuration Tool. TheGFS Setup Druiduses/etc/cluster.xmlas input. If/etc/cluster.xmldoes not exist, the
GFS Setup Druiddisplays a message and exits. Note
You must run theCluster Configuration Toolbefore running theGFS Setup Druid; theCluster Configuration Toolcreates/etc/cluster.xml.
To run theGFS Setup Druid, enter the following at the command line: # redhat-config-gfscluster
gulm-bridge
This is a fence method available for Red Hat Cluster nodes,ifandonly ifthe Red Hat GFS RPM is installed on the node that theCluster Configuration Toolruns on. The gulm-bridge fence method has been added to Red Hat Cluster Suite specifically for the Red Hat Enterprise Linux 3 Update 3 release. Using this fence method on a Red Hat Cluster Manager member prevents it from being fenced twice.
Red Hat Cluster
Red Hat Cluster Manager is part of the Red Hat Cluster Suite. It provides cluster administration functionality for Red Hat Enterprise Linux 3. Red Hat Cluster Manager contains two major components:
• Red Hat Cluster Manager— The underlying software (non-GUI) that performs Red Hat Cluster administrations services.
• Cluster Configuration Tool— This component is the graphical user interface (GUI) for Red Hat Cluster Manager. The GUI provides a configuration interface and a status monitor for members and services in a Red Hat Cluster Manager system. TheCluster Configuration Toolaccepts configuration data from a user and writes it to the/etc/cluster.xmlfile. The