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Difficulty: HardDesigning Migration Plans and Data Transfer Strategies

An enterprise gaming company is planning to migrate its mission-critical PostgreSQL database and associated multi-terabyte media storage from an on-premises data center to Google Cloud (Cloud SQL for PostgreSQL and Cloud Storage) with minimal operational downtime. What is the correct sequence of steps to execute this migration strategy while ensuring zero data loss and minimal service interruption?

  1. 1Establish dedicated network connectivity via Cloud Interconnect and set up target GCP IAM roles and VPC infrastructure.
  2. 2Initiate initial baseline data transfer for media files to Cloud Storage via Storage Transfer Service and start continuous Database Migration Service (DMS) CDC replication.
  3. 3Verify data consistency, schema validation, and monitor CDC replication lag between the on-premises database and Cloud SQL.
  4. 4Place the on-premises database in read-only mode, allow final CDC catch-up, and promote the Cloud SQL instance to primary.
  5. 5Update client application database connection strings and DNS records to direct production traffic to GCP.

Answer

The correct sequence of steps is: 1) Establish dedicated network connectivity via Cloud Interconnect and set up target GCP IAM roles and VPC infrastructure, 2) Initiate initial baseline data transfer for media files to Cloud Storage via Storage Transfer Service and start continuous Database Migration Service (DMS) CDC replication, 3) Verify data consistency, schema validation, and monitor CDC replication lag between the on-premises database and Cloud SQL, 4) Place the on-premises database in read-only mode, allow final CDC catch-up, and promote the Cloud SQL instance to primary, and 5) Update client application database connection strings and DNS records to direct production traffic to GCP.
The correct sequence follows GCP migration best practices: pre-provisioning secure network and IAM foundations, establishing baseline file transfers alongside continuous database replication (CDC), validating sync status, executing a zero-loss cutover (setting source read-only, draining CDC, promoting target), and re-pointing application endpoints.

Step-by-Step Solution

1
Provision underlying network and access foundations.
Secure, high-bandwidth connection between on-premises and GCP VPC is established.
Data migration tools and replication streams require network routes and IAM permissions before initiation.
2
Start baseline storage migration and continuous database replication.
Historical media files land in Cloud Storage while database CDC catches up initial state.
Both file transfer and CDC replication run concurrently to minimize overall migration timeline.
3
Validate synchronization status and replication lag.
Target environment parity is confirmed with minimal CDC replication lag.
Cutting over without verifying synchronization risks data loss or extended cutover downtime.
4
Execute database cutover sequence: set source read-only, drain CDC stream, and promote target.
Target Cloud SQL instance becomes the writable primary database with zero lost transactions.
Locking writes at the source prevents data divergence and guarantees transactional consistency.
5
Re-point application traffic to the target GCP environment.
Production traffic successfully operates against GCP.
Final stage switches active workload to GCP once the target database is promoted and operational.

Key Concept

Staging continuous database and data transfer migrations to achieve minimal downtime and zero data loss on GCP.
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Topics

Designing Migration Plans and Data Transfer Strategies