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Difficulty: MediumDesigning Migration Plans and Data Transfer Strategies

A financial analytics company is migrating its historical transaction log archive (120 TB120\text{ TB}) and an operational 500 GB500\text{ GB} MySQL database from an on-premises data center to Google Cloud. The environment has an active 1 Gbps1\text{ Gbps} Cloud Dedicated Interconnect connection to GCP. The migration plan requires completing the archive movement with minimal operational overhead, while minimizing downtime for the operational database during a planned 4-hour maintenance window. Which data transfer and migration strategy should the Cloud Architect recommend?

  1. Use Storage Transfer Service to transfer the 120 TB120\text{ TB} log archive to Cloud Storage over the Dedicated Interconnect, and use Database Migration Service (DMS) with continuous replication to migrate the MySQL database to Cloud SQL.Answer
  2. B
    Order a Google Cloud Transfer Appliance to physically transfer the 120 TB120\text{ TB} log archive, and perform a manual database export using mysqldump to import into Cloud SQL during the cutover window.
  3. C
    Use Storage Transfer Service for the 120 TB120\text{ TB} log archive, but migrate the operational MySQL database to Cloud Spanner using custom batch export scripts during the cutover window.
  4. D
    Provision an IPSec HA VPN tunnel over the public internet to migrate both the 120 TB120\text{ TB} log archive via Storage Transfer Service and the MySQL database via Database Migration Service.

Answer

The optimal strategy is to use Storage Transfer Service to move the log archive to Cloud Storage over the Dedicated Interconnect, and use Database Migration Service with continuous replication to migrate the MySQL database to Cloud SQL.
Transferring 120 TB over a 1 Gbps Dedicated Interconnect takes roughly 11.6 days of continuous transfer, which fits standard online migration preparation timelines using Storage Transfer Service. For the 500 GB MySQL database, Database Migration Service (DMS) establishes Change Data Capture (CDC) replication from on-premises to Cloud SQL prior to cutover, allowing a zero-data-loss cutover well within the 4-hour maintenance window.

Step-by-Step Solution

1
Evaluate bandwidth and timeframe for the 120 TB static log archive.
At 1 Gbps dedicated bandwidth, transferring 120 TB online takes approximately 11 to 12 days, making online transfer with Storage Transfer Service ideal without requiring physical device shipping.
Storage Transfer Service handles network bandwidth throttling, retries, and data integrity validation over private Cloud Interconnect connections.
2
Evaluate database cutover downtime requirements for the 500 GB MySQL database.
Continuous replication using Database Migration Service (DMS) keeps the Cloud SQL target instance synchronized with the source database in near real time.
DMS continuous replication minimizes cutover downtime to minutes (promoting the standby target), easily satisfying the strict 4-hour maintenance window requirement.

Key Concept

Selecting Online Data Transfer vs. Physical Appliances and Continuous Database Replication Strategies
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Topics

Designing Migration Plans and Data Transfer Strategies