What is the difference between glass fish configuration, server, instance and cluster?

Question

The following is a paragraph made of glass fish 3.1.2.2 Administration Guide

You can manually rotate log files using the rotate-log subcommand remotely. The default purpose of this subcommand is DAS. Optionally, you can target the configuration, server, instance or cluster . You can manually rotate log files using the rotation log of a subcommand remotely. The default purpose of this subcommand is DAS. Optionally, you can target the configuration, server, instance, or cluster.

What is the difference between configuration, server, instance and cluster? I understand that a cluster is a collection of instances. but what is the difference between server and instance and configuration?

Answer 1

From the Glassfish admin guide:

The default target for these two subcommands is DAS. However, you can optionally specify one of the following goals:

Configuration . To target all instances or clusters with a common configuration name.
Server : to install only a specific server.
Instance : to specify only a specific instance.
Cluster : targets only a specific cluster.

The GlassFish Server instance is a single virtual machine for the Java platform (Java virtual machine or JVM machine) on a single node that runs on GlassFish Server. A node defines the host where the GlassFish Server Instance is located.

and

It is usually sufficient to create an instance of one server per machine, since GlassFish Server and its companion JVMs are designed to scale to multiple processors. However, it can be useful to create multiple instances on the same computer to isolate applications and update rental.

This means that you can use multiple instances on the same server that you can use for one or more servers.