Zero Downtime Migration – Monitor GoldenGate Replication

When you are migrating your Oracle Database with Zero Downtime Migration (ZDM) and the Logical Online method, you are using Oracle GoldenGate to handle the replication. The replication keeps the OCI target database in sync until you can perform the switchover. Thus, it is a vital part of the process. Let’s see how you can monitor the replication.

I have already started a migration which is currently paused at the phase ZDM_MONITOR_GG_LAG.

Monitor Services

Log on to the Oracle GoldenGate Hub via HTTPS. Use the host name, private or public IP address or whatever your network allows.

You are prompted for credentials. Log on as oggadmin – in lowercase. The password you can find in the file ogg-credentials.json which you find on GoldenGate Hub. The log in prompt of Oracle GoldenGate

Once logged in you can ensure that all the services are up and running. Most important are the Administration Server services – on source and target. They are handling the replication. Ensure all services are running You can start and stop the services from the Action drop-down menu.

By clicking on the Port number of each of the services, you can go to the specific console for each of the services. Again, the Administration Server are the ones of interest. Click on the port number to go to the specific console

Monitor Extract

If you followed the link to the Source Administration Server (by clicking on the port number) you end up here: Administration Server overview

Ensure that the extract is running. Further down the page you see a list of events. From the Action drop-down menu, you can start and stop the extract. And you get into the Details as well: Follow the Details link

You can get a lot of details, like extract statistics. Here you can see that extract has caught one insert into the table locations: Extract statistics

Monitor Replicat

Now you have monitored the extract, and you should also monitor the replication, which is handled by the replicat process. Basically, you do the same as with extract but use the link on the target administration server: Follow the link to the target administration server to monitor the replicat process

Here you should look at the replicat process and ensure that it is running: Ensure replicat process is running

You start and stop the services and get into the details like described above.

Troubleshooting

Here is an example of an error. I have created a table in my source database that does not exist in the target. This break the replication. I can use the list of critical events to figure out what went wrong: Replicat failed

Also, if you go into the details of the replicat process, and switch to the report tab, you can find even more details:

You can also find more logs on the GoldenGate host in the directories:

  • /u02/deployments/Source/etc/conf/ogg/
  • /u02/deployments/Target/etc/conf/ogg/

Conclusion

With Oracle GoldenGate Microservices Architecture it is actually not that hard to get an overview of the replication process. There are nice graphical overviews and you can even get detailed information and statistics.

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