The satellite environment is an environment in which you can administer large numbers of DB2 servers from a central control site.
In the satellite environment, you set up collections of DB2 servers. Each collection is known as a group. Each DB2 server that belongs to a group is called a satellite. You use groups to organize satellites that have shared characteristics into single entities. The characteristics that many satellites could share are the end-user application that runs on them, and the database definition that supports the application.
| Note: | For this document, database definition is the entire setup of DB2, including, but not limited to, the instance, the database manager configuration parameter values, the database design, and the database configuration parameter values. |
In a group, the satellites are similar in terms of their database definition, usage, and purpose. For example, assume that there are two groups in your organization, Sales and Support. The Sales group would require one end-user application and database definition, while the Support group would require a different end-user application and database definition.
By grouping the satellites together, you administer small numbers of groups, which may contain hundreds, if not thousands of satellites, rather than having to administer each satellites individually. If you acquire additional DB2 servers to perform the same function as the satellites of an existing group, you can add them to that group. The administration solution provided by the satellite environment is fully scalable.
In the satellite environment, the setup and maintenance of any database definition is accomplished by sets of scripts known as batches. Because the database definition can be different for each group, each group has its own set of batches. The batches that are specific to a group are known as group batches.
Within a group, satellites may run different versions of the end-user application, and each version of the end-user application may require its own database definition and data. Group batches are always associated with a particular application version. The application version represents the database definition and data that support a particular version of the end-user application.
Each DB2 server that belongs to a group is known as a satellite. A satellite, because it belongs to a group, will have the same end-user application as the other satellites in the group. Depending on its version of the end-user application, however, it may share its database definition and data with only a subset of the satellites that belong to its group.
Information about the satellite environment is stored in a central database known as the satellite control database. This database records, among other things, which satellites are in the environment, the group each satellite belongs to, and which version of the end-user application a satellite is running. It also records the group batches that the satellites execute. This database is on a DB2 server that is known as the DB2 control server.
To set up and maintain its database definition, each satellite connects to the satellite control database to download the batches that correspond to its version of the end-user application. The satellite executes these batches locally, then reports the results back to the satellite control database. This process of downloading batches, executing them, then reporting the results of the batch execution is known as synchronization. A satellite synchronizes to maintain its consistency with the other satellites that belong to its group and that run the same version of the end-user application.
In the satellite environment, DB2 can be hidden from your end users: they do not need to learn about database administration. Instead, you can administer the satellite environment centrally from the Satellite Administration Center, which is a set of graphical tools that is available from the Control Center.
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