HP Serviceguard Enterprise Cluster Master Toolkit User Guide, December 2012 (5900-2145)

Tomcat Package Configuration Overview
To start up, Tomcat read the server.xml file from the conf sub-directory of the CATALINA_BASE
directory which is configured in the toolkit user configuration file hatomcat.conf.
The configuration rules include the following:
• Each node must have the same version of the HP-UX based Tomcat Servlet Engine.
• Each node must have the same CATALINA_BASE directory where identical copies of the
configuration file for each instance are placed.
• Each node must have the same document root directory where identical copies of the web
document for each instance are placed.
You can configure Tomcat servlet engine in the following ways:
• Local config: Place the configuration and other web-site files on a single node, and then
replicate the files to all other nodes in the cluster
• Shared config: Share the engine with configuration files and document root files in a shared
file system
NOTE: Under a shared configuration, you can place tomcat binaries in a shared file system.
Local configuration
In a typical local configuration, no files are shared between the nodes. Identical copies of the
Tomcat server configuration file and web documents reside in exactly the same locations on each
node. You must maintain identical copies of the tomcat components on the different nodes. This is
useful when the information on the web-page is static.
If you select this configuration, ensure that the data is propagated to all nodes, and is consistently
maintained. It might be a disadvantage to store the configuration on local disks because if changes
are made to the configuration, a Tomcat instance might become inconsistent and might not distribute
data to all nodes that can run that Tomcat instance.
Shared configuration
In a typical shared configuration, the web application directories are all on the shared file system.
(Placing the CATALINA_BASE directory in the shared file system is optional.) The web applications
(along with the tomcat configuration directory) are on shared storage which is accessible to all
nodes in the cluster, therefore, there is no need to maintain local identical copies of the files on
each node. The mount point of the shared file system must be identical across all the tomcat package
nodes. Hence this is the recommended Tomcat package configuration.
Each web site is assigned IP addresses (or domain addresses that maps to particular IP addresses)
through the configuration file. These relocatable IP addresses are created for each Tomcat package.
In Legacy packages, they are added to the Package Control Script and in modular packages the
Package ASCII file. When the Tomcat package is switched over from one node to another, this
particular instance is stopped and IP addresses are removed from the primary node. The IP addresses
are then reallocated and the instance is started on the adoptive node. Clients are automatically
connected through these IP addresses to the web site on the adoptive node.
Multiple Tomcat Instances Configuration
Tomcat servlet engine is a multi-instance application. On a single node, you can simultaneously
run more than one instance of the Tomcat. For example, if two Tomcat instances are running on
two separate nodes and one node fails, you can failover the instance on the failed node to the
healthy node. In addition, the healthy node can continue to run its own instance. Multiple Tomcat
instance configuration can either be done as a local configuration or shared configuration or a
combination of both. CATALINA_BASE needs to be unique for each Tomcat instance.
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