The Challenge
Migrating a large (2.0 TB) Oracle database from an on-premises server to Oracle Cloud Infrastructure (OCI) with less than 30 minutes of downtime is complex. Our client challenged us to do just that. Here are some challenges the Performance One Data Solutions team considered during this complex Oracle Cloud Database Migration:
Data Transfer Speed and Volume:
- Transferring 2.0 TB of data can be time-consuming, especially if you rely on public internet connectivity.
- Ensure that your network bandwidth can handle the data transfer efficiently.
Network Latency and Connectivity:
- Network latency between the on-premises environment and OCI can impact migration.
- Optimize network connectivity to minimize latency and ensure smooth data transfer.
Downtime Constraints:
- Achieving less than 30 minutes of downtime requires meticulous planning and execution.
- Coordinate with stakeholders to schedule a maintenance window during off-peak hours.
Application Dependencies:
- Identify applications that rely on the Oracle database. Ensure they can tolerate the migration process and potential downtime.
- Update connection strings and configurations to point to the new database location.
Testing and Validation:
- Rigorously test the migration process in a non-production environment.
- Validate data consistency, application functionality, and performance after the migration.
Security and Access Control:
- Securely transfer sensitive data during migration.
- Set up proper access controls and permissions for users and applications in OCI.
Backup and Rollback Strategy:
- Develop a robust backup strategy before starting the migration.
- Be prepared for any unforeseen issues by having a rollback plan.
Monitoring and Troubleshooting:
- Monitor the migration progress using relevant tools and logs.
- Be ready to troubleshoot any errors or issues during the process.
Database Version and Features:
- Ensure the source and target databases are compatible with Oracle versions and features.
- Plan for any necessary upgrades or adjustments.
Remember that meticulous planning, thorough testing, and collaboration with your team are essential for a successful migration.
The Solution
Our chosen approach was migrating a 2.0 TB Oracle Database from an on-premises server to Oracle Cloud Infrastructure (OCI) using Oracle Zero Downtime Migration (ZDM) and GoldenGate Microservices. Let’s break down the solution:
Oracle Zero Downtime Migration (ZDM):
- ZDM is a powerful tool designed for seamless database migrations with minimal downtime. It automates the migration process, ensuring data consistency and reducing manual effort.
- Key features of ZDM include:
- Automated Assessment: ZDM assesses your source database and provides recommendations for migration.
- Data Pump Export/Import: ZDM uses Data Pump to export data from the source database and import it into the target OCI database.
- GoldenGate Integration: ZDM leverages GoldenGate for real-time data replication during the migration.
- Automated Cutover: ZDM orchestrates the final cutover, minimizing downtime.
- Detailed Reports: ZDM generates comprehensive reports for auditing and troubleshooting.
GoldenGate Microservices:
- GoldenGate is a robust data replication solution. In this scenario, we use GoldenGate Microservices to continuously synchronize data between the source and target databases.
- Key features of GoldenGate Microservices include:
- Extract and Replicat Processes: These processes capture changes from the source database and apply them to the target.
- Integrated with ZDM: ZDM configures GoldenGate for real-time replication during the migration.
- High Availability: GoldenGate ensures data availability even during the migration process.
- Minimal Impact on Source Database: GoldenGate operates with low overhead on the source system.
Migration Steps:
- Here’s a high-level overview of the migration process:
- Assessment:
- Run ZDM assessment to analyze the source database.
- Address any issues identified (e.g., unsupported features, data types).
- Preparation:
- Set up the target OCI database.
- Configure GoldenGate Microservices.
Data Synchronization:
- Start GoldenGate Extract process on the source.
- Configure Replicat process on the target OCI database.
- Data changes are continuously replicated.
Final Cutover:
- Schedule a maintenance window.
- Stop application writes to the source database.
- Run ZDM cutover to switch to the target database.
Post-Migration Validation:
- Verify data consistency.
- Update application connection strings to point to the new database.
The Results
Successfully migrated data, kept target data updated for three weeks while other application conversion efforts were ongoing, and successfully presented the migrated data with less than 30 minutes of downtime.
Benefits:
- Minimal Downtime: GoldenGate keeps the target database up-to-date, allowing for a smooth cutover.
- Automated Process: ZDM automates most steps, reducing manual effort.
- Cost-Effective: ZDM is available at no additional cost.
Remember to thoroughly test the migration in a non-production environment before performing it.
