Data migration in these systems typically occurs during what?

Data migration in these systems typically occurs during what?

• A. Real-time reads
• B. After every failure
• C. Never
• D. Planned capacity changes

Answer: (D)

Data migration is typically tied to changing how the system is deployed or scaled. When you plan to add or remove capacity, you reorganize where data lives, move partitions or shards, and rebalance across nodes. This is a deliberate, coordinated operation designed to keep performance and availability while the topology changes. Real-time reads are ongoing operations and don’t imply moving data; the migration happens as a separate, planned step. Doing migration after every failure is not the standard routine—it’s more about recovery and restoration, not regular capacity planning. Saying it never happens isn’t accurate because scaling or reorganizing storage requires moving data. So the best choice is that data migration occurs during planned capacity changes.

Data migration is typically tied to changing how the system is deployed or scaled. When you plan to add or remove capacity, you reorganize where data lives, move partitions or shards, and rebalance across nodes. This is a deliberate, coordinated operation designed to keep performance and availability while the topology changes. Real-time reads are ongoing operations and don’t imply moving data; the migration happens as a separate, planned step. Doing migration after every failure is not the standard routine—it’s more about recovery and restoration, not regular capacity planning. Saying it never happens isn’t accurate because scaling or reorganizing storage requires moving data. So the best choice is that data migration occurs during planned capacity changes.