2 Preparing to Migrate to OCI GoldenGate

Before you start migrating to OCI GoldenGate, ensure that you consider downtime requirements of your current environment and carefully plan and create what you need for OCI GoldenGate.

Downtime Requirements

This migration process minimally impacts the availability of your current Oracle GoldenGate instance in Oracle Cloud Infrastructure Classic, Marketplace, or on premise. Your current, to-be-migrated Oracle GoldenGate instance's processes will be stopped per migration workflow. When the migration completes, the replication process resumes from where it was stopped. The production database must not have running active transactions to ensure the migration completes smoothly.

Your current Oracle GoldenGate instance's files, such as configuration files, report files, and trail files, are not impacted by the migration.

After the migration completes successfully, clients can be rerouted to OCI GoldenGate.

Network Considerations

OCI GoldenGate is a fully managed cloud service, which means you have no direct access to the underlying operating system resources. Therefore, you're not able to transfer data directly to OCI GoldenGate by copying data directly on to the disk mounts.

When migrating an Oracle GoldenGate instance that's part of the Data Integration Platform Cloud (DIPC) Agent, consider the network performance implications beforehand.

The following information applies to all platforms supported by Oracle GoldenGate for Oracle-to-Oracle replication. The network requirements for Oracle GoldenGate are as follows:

• Extract: If running Oracle GoldenGate remotely on a server separate from the database you're capturing from, then performance may be impacted if latency is greater than 80 milliseconds (ms). For Integrated Extract, only the changes to the tables that are being captured are sent to the Extract process itself.
• Replicat: If running Oracle GoldenGate remotely on a server separate from the database Oracle GoldenGate applies changes to, then performance may be impacted if the latency is greater than 5ms.
• For Oracle GoldenGate to Oracle GoldenGate communication: If you're capturing 100% of the data, then the trail files grow at 30-40% of the generated redo log volume. This means that Oracle GoldenGate sends 30-40% of the generated redo log volume across the network. If the network isn't able to scale to this volume, you can enable compression on the trail file data sent across the network. This compression can typically achieve 8:1 compression ratio or better. You can also modify the TCP window socket size and buffers as well.

Creating Required OCI Resources

Before you migrate to OCI GoldenGate, you must create the required OCI resources:

• Compartments
• VCNs and Subnets
• Users and Groups
• Policies

For more information, see Getting Started with GoldenGate.

Selecting Deployment Shapes

Before you can migrate to OCI GoldenGate, ensure that you set up your OCI GoldenGate resources. When you create an OCI GoldenGate deployment, you're asked to select the number of Oracle Compute Units (OCPUs) the deployment needs.

To idenfity the number of compute shapes for OCI GoldenGate, consider providing similar or higher resources to the shapes you're currently using for your Oracle GoldenGate Cloud Classic or Oracle GoldenGate on Oracle Cloud Infrastructure Classic, Marketplace, or on premise instance.

Oracle Cloud Infrastructure and Oracle Cloud Infrastructure Classic each has its own set of standard compute shapes. For more information, see:

• About Shapes
• Metering and Billing
• Creating a Deployment

OCI GoldenGate also allows you to enable Auto Scaling. When you enable auto scaling, the deployment can scale up to three times more compute and memory than the number of OCPUs currently shown in the Scale dialog. One OCPU is equivalent to 16 GB memory. If your workload requires additional OCPUs, then the deployment automatically uses the resources without any manual intervention required when auto scaling is enabled. For more information, see Scaling a Deployment.

Performing Pre-Migration Tasks

Complete the following steps before starting your migration:

1. Back up and secure the data on cloud storage for the Oracle GoldenGate instance you're migrating. Data includes configuration files and trail file data. For steps to perform the backup, see Perform Backup and Restore.
   • The Oracle GoldenGate Cloud Classic data location is /u02/data/ggdata.
   • The DIPC data location is in the Agent installation directory, $OGG_HOME/data.
   • The on premise data location is $OGG_HOME/data.
   • The Oracle GoldenGate Marketplace default data location is /u02/trails.
2. For Oracle GoldenGate Cloud Classic or Oracle GoldenGate Marketplace that receive trails from Oracle GoldenGate Classic architecture:
   • Because OCI GoldenGate is a fully managed cloud service, no configuration files or trail files are allowed to move into OCI GoldenGate deployments.
   • If the Oracle GoldenGate instance you're migrating is receiving trail files from another Oracle GoldenGate Classic instance (let's refer to it as "Dist-instance"), you must first convert Dist-instance into a Micoservices instance.
3. If you're using Classic Extract in the Oracle GoldenGate instance you're migrating, you won't be able to create the same in OCI GoldenGate; you must switch to Integrated Extract. Ensure that you have all required database patches installed to use Integrated Extract. See Recommended patches for Oracle 12c or higher.