Question

Difficulty: MediumDesigning Migration Plans and Data Transfer Strategies

A regional healthcare provider needs to migrate its core application workload to Google Cloud within a strict 3-week cutover window. The existing environment consists of a 650 TB static medical imaging archive and an active 400 GB MySQL operational database. The facility has a dedicated network connection with 100 Mbps of available uplink bandwidth, and the database requires minimal downtime during final cutover. Which migration strategy should a Cloud Architect recommend?

  1. Order a Google Cloud Transfer Appliance to transfer the 650 TB medical imaging archive offline, and use Database Migration Service (DMS) with continuous replication for the 400 GB MySQL database cutover.Answer
  2. B
    Use Storage Transfer Service to stream both the 650 TB medical imaging archive and the operational database snapshot concurrently over the 100 Mbps network connection.
  3. C
    Migrate the 400 GB operational database into Cloud Spanner, and stream the 650 TB imaging archive directly into Cloud Spanner tables using batch upload scripts.
  4. D
    Configure an HA VPN connection to a transit VPC, and rely on transitive routing over VPC Network Peering to stream all imaging files and database data to destination buckets in a peered workload VPC.

Answer

Order a Google Cloud Transfer Appliance to transfer the 650 TB medical imaging archive offline, and use Database Migration Service (DMS) with continuous replication for the 400 GB MySQL database cutover.
The solution correctly identifies that moving 650 TB over a 100 Mbps internet connection takes over 600 days, making online transfer impossible within a 3-week timeframe. Transfer Appliance provides an offline physical shipping device capable of ingesting petabyte-scale data into Cloud Storage. Meanwhile, the 400 GB operational MySQL database can easily be seeded online and kept in continuous synchronization using Database Migration Service (DMS) with Change Data Capture (CDC) until final cutover.

Step-by-Step Solution

1
Calculate network throughput for the static data payload
Moving 650 TB650\text{ TB} (5.2×106 Gb5.2\times 10^6\text{ Gb}) over a 100 Mbps100\text{ Mbps} (0.1 Gbps0.1\text{ Gbps}) link requires approximately 5.2×107 seconds601 days5.2\times 10^7\text{ seconds} \approx 601\text{ days}, exceeding the 3-week window.
Large multi-hundred terabyte datasets cannot be moved online over narrow bandwidth pipes within short project timelines.
2
Select the appropriate data transfer mechanism for large static payloads
Select Google Cloud Transfer Appliance for offline physical data transport.
Transfer Appliance allows copying data locally at high speed and shipping hardware securely to a Google data center for ingestion into Cloud Storage.
3
Select database migration strategy for low downtime
Use Database Migration Service (DMS) with initial snapshot and Change Data Capture (CDC) continuous replication over the 100 Mbps100\text{ Mbps} connection.
A 400 GB400\text{ GB} database transfer easily fits within the 100 Mbps100\text{ Mbps} bandwidth capacity (taking roughly 9 hours9\text{ hours} for initial load), and CDC enables near-zero downtime cutover.

Key Concept

Selecting data transfer mechanisms based on data volume, bandwidth constraints, and downtime requirements
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