The following general method can be used to perform a parallel upgrade with replication:
Install a new copy of Adaptive Server 15.0.
Copy in or load pre-release 15.0 databases.
Use Replication Server to maintain both sets of databases. The 15.0 system becomes the primary server, and you maintain the pre-15.0 system as a warm standby.
Plan for all users to reconnect to the earlier version server after you take Adaptive Server verion 15.0 off line. Make TCP/IP address and port changes where appropriate.
Test the fallback process as part of the application test suite (these are a series of tasks that test your application). This suite should do both of the following:
Insert data into Adaptive Server version 15.0. The data must be replicated and available in the earlier server.
Execute the fallback script.
Consider making daily bcp dumps of the databases. To fall back, load the dumps into the earlier server. Keep in mind:
You may need to modify the databases to support incremental bcp dumps.
The earlier server cannot read version 15.0 backup files. Create bcp or other scripts to move tables back to pre-15.0.
Do not apply schema enhancements.
For information about scheduling backups of user databases, see the System Administration Guide.
Additional tips:
Upgrade Replication Server first.
Be sure the applications are using the correct server. For details on the interfaces file and the $DSQUERY environment variable, see the Configuration Guide for your platform.
Remember to include client fallback time in the calculation.
For sites that are perpetually running, load time delays can impact synchronization. Consider replicating to Adaptive Server 15.0, then switching servers.
Execute this suite before switching users to the new system.
Since the parallel-with-replication approach is best for high availability applications, it is imperative that the test suite address both update correctness and performance acceptability.
See Chapter 6, “Ensuring Stability and Performance” for more information on testing.
After successful validation, consider having users enter
production queries. You should perform your tests with a realistic
production load. A good time to perform the tests is after hours
or during production lulls.
There should not be any user impact during migration. The more stringent the validation test is, the less likely you are to have issues during migration.
To ensure correct updates and acceptable performance, test the replicated environment.
The environment used for Adaptive Server vesion 15.0 must be more powerful than for earlier version to handle query and replication loads. See the Replication Server Configuration Guide for your platform for more information.
Be sure to account for any increased release 15.0 memory requirements that apply to your configuration. For more information, see:
The installation guide for your platform for basic RAM requirements.
The Adaptive Server System Administration Guide for information about configuring memory and data caches.
The Performance and Tuning Guide for Information on how to configure memory for performance.
For a production system, execute the performance suite
during off hours.
Developing and running the replication facility, validation and performance suite, and fallback script requires significant effort. If your environment already uses replication, this effort will be notably easier.
For a development system, you may want to add a short period to the development schedule for release 15.0 issues.
For a production system, be prepared to postpone or fall back, if needed.
