Administering Satellites Guide and Reference

Satellite Synchronization

The satellites of a particular group need to be in a state consistent with the other satellites of its group. The consistent state can be accomplished with synchronization.

Figure 2 provides a high-level view of how a satellite synchronizes. Before the satellite can synchronize, it must connect to the network on which the DB2 control server resides. The satellite can connect with the network in a variety of ways, such as by a dial-up program, by docking with the network, or by remaining permanently connected to the network.

Figure 2. Satellite Synchronization

The satellite synchronizes as follows:

1. The end-user of the satellite invokes the synchronizer function. The invocation can be from your user application (if it calls the db2SyncSatellite API), or from the DB2 Synchronizer application that is provided with DB2. For information about the APIs that an application can call for synchronization, see Synchronizing a Satellite. Also refer to the Administrative API Reference. For information about the DB2 Synchronizer, see Using the DB2 Synchronizer Application.

   When the synchronizer function is invoked, steps 2 through 8 occur automatically. No manual intervention is required.

   The satellite is only connected to the satellite control database for step 3, and for step 7.

2. The satellite connects to the satellite control database, where it is authenticated.
3. After authentication occurs, the DB2 control server checks which group the satellite belongs to, and the version of the application that the satellite is executing. The DB2 control server uses this information to determine which batches the satellite should execute, and which batch steps should be executed, if any. At this time, other events may also occur:
   1. If the satellite could not upload the results of its previous synchronization session to the satellite control database, the results are written at this time.
   2. If any of the scripts in a batch to be downloaded are parameterized, the DB2 control server instantiates the script with the values that are appropriate for the satellite. For more information about parameterized scripts, see Parameterizing Scripts.
   3. When steps 3a and 3b are complete (if required), the DB2 control server releases the scripts that the satellite is to execute, and the satellite downloads them. When this occurs, the tables in the satellite control database are updated to indicate that the satellite has obtained the batches that apply to it.
4. The synchronizer function drops the connection with the satellite control database.
5. The satellite executes the batches that it downloaded.
6. After executing the batches, the synchronizer function again connects to the satellite control database.
7. The synchronizer function updates the log information in the satellite control database with the results of the execution of the different steps of the batches. The log information provides details about the execution of the batch steps. For information about these logs, refer to the online help that is available from the Satellite Administration Center.
8. The synchronizer function drops the connection with the satellite control database.

After the synchronization session is complete, the satellite can be disconnected from the network, if required.

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