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Ce document étudie les infrastructures et les différents types et méthodes de haute disponibilité dans un environnement donné. Il présente aussi les différentes solutions en termes logiciels et matériels afin de parvenir à une haute disponibilité. Ce document est une documentation ouverte.

Many IT administrators have discovered that there is overlap between consolidation and virtualization, and they are wondering how they should reconcile these two techniques in datacenter environments. Virtualization tools such as partitions, virtual machines, and resource management software all enable multiple dominant workloads to run simultaneously on larger servers, which is typically a key aspect of consolidation. But virtualization also offers far-reaching opportunities for administrators to fundamentally transform the operations in their datacenters.

Server clusters and server virtualization may be two different animals, but they're animals that can work well together in a data center, says Hakon Bugge, founder and CTO of Scali Inc., a Linux clustering systems provider in Marlborough, Mass.

Clustering allows us to run an applications on several parallel servers (a.k.a cluster nodes). The load is distributed across different servers, and even if any of the servers fails, the application is still accessible via other cluster nodes. Clustering is crucial for scalable enterprise applications, as you can improve performance by simply adding more nodes to the cluster. The JBoss Application Server (AS) comes with clustering support out of the box. The simplest way to start a JBoss server cluster is to start several JBoss instances on the same local network, using the run -c all command for each instance. Those server instances, all started in the all configuration, detect each other and automatically form a cluster. In the first section of this chapter, I discuss basic concepts behind JBoss's clustering services. It is important that you understand those concepts before reading the rest of the chapter. Clustering configurations for specific types of applications are covered after this section.

C-JDBC is a database cluster middleware that allows any Java™ application (standalone application, servlet or EJB™ container, ...) to transparently access a cluster of databases through JDBC™. You do not have to modify client applications, application servers or database server software. You just have to ensure that all database accesses are performed through C-JDBC.

General Informations and FAQ about JK. JK is a project covering web-servers to Tomcat connectors, whereas mod_jk is the Apache module developed in JK.JK is a project covering web-servers to Tomcat connectors, whereas mod_jk is the Apache module developed in JK.

Running cluster of Tomcat servers behind the Web server can be demanding task if you wish to archive maximum performance and stability. This article describes best practices how to accomplish that.