Database migration

[rakku99]

I have migrated the databases from On-Prem to Cloud Storage.  Now I want to migrate the database from cloud storage to Cloud SQL. The data size can be large. what is right architecture for this approach. I do not want to use the database emigration service.

[ms4446]

You can use the following approach to migrate from GCS to Cloud SQL (without using the DMS). 

1. Pre-Migration Planning

• Database Type: Identify the specific database engine (MySQL, PostgreSQL, SQL Server) to ensure compatibility and optimize the migration process accordingly.

• Data Size Assessment: Knowing the size (in GB or TB) is crucial for planning the instance size, estimating migration time, and potential downtime.

• Data Format Verification: Ensure the data in GCS is in a format compatible with Cloud SQL's import capabilities (e.g., SQL dump for MySQL/PostgreSQL, BAK for SQL Server).

• Downtime Evaluation: Assess how much downtime is acceptable to determine the migration window and whether a phased approach is feasible.

2. Cloud SQL Instance Preparation

• Instance Sizing: Based on the data size and expected workload, choose an instance with adequate CPU, RAM, and storage. Consider provisioning additional resources to accommodate the import process, which can be scaled down post-migration.

• Configuration: Apply necessary configurations, such as IP whitelisting, database flags, and any engine-specific settings, to optimize performance and security.

3. Data Preparation and Optimization

• Data Splitting: For very large datasets, consider splitting the data into smaller chunks. This can facilitate parallel imports, reducing overall migration time. Ensure the split maintains data integrity and respects relational dependencies.

• Format Conversion: If the data isn't already in a Cloud SQL-compatible format, use appropriate tools to convert it. This step might require local resources or temporary Compute Engine instances for processing.

4. Migration Execution

• Parallel Imports: Utilize the gcloud sql import sql command for MySQL/PostgreSQL or the Cloud SQL Import functionality for SQL Server to import data chunks in parallel. This approach minimizes downtime and accelerates the migration process.

  gcloud sql import sql [INSTANCE_ID] gs://[BUCKET_NAME]/[CHUNKED_SQL_DUMP_FILE] --database=[DATABASE_NAME] --quiet

• Batch Processing: For SQL imports, consider breaking down large SQL dump files into smaller transactions to avoid memory overflow and manage the transaction log size effectively.

5. Post-Migration Adjustments

• Instance Optimization: After the migration, adjust the Cloud SQL instance size to match the regular operational workload, reducing costs without compromising performance.

• Validation: Conduct thorough testing to ensure data integrity, performance benchmarks, and application functionality are as expected.

6. Monitoring and Troubleshooting

• Import Monitoring: Monitor the import process closely for any errors or performance bottlenecks. Google Cloud's operations suite can provide valuable insights into resource utilization and potential issues.

• Error Handling: Prepare to address common import errors, such as timeouts or format inconsistencies. Adjusting batch sizes, increasing timeouts, or modifying data formats may be necessary.

7. Final Considerations

• Network Optimization: Ensure the GCS bucket and Cloud SQL instance are in the same region to minimize latency and transfer costs.

• Downtime Communication: Communicate planned downtimes clearly to stakeholders and users, aligning with the least disruptive schedule.