How Does Migration Affect Data in the Destination Bucket?

The impacts of migration on existing data in destination buckets depend on whether objects with the same name exist in the source and destination buckets.

• If no object with the same name exists, the migration has no impacts on the existing data in the destination bucket.
  • Data in the destination bucket is not modified during the migration.
  • Data in the destination bucket is not deleted after the migration.
• If objects with the same name exist, whether these objects are overwritten by those migrated from the source bucket depends on the overwriting policy you configure for the migration task or task group. For details about the policies, see Table 1.

  Table 1 Policies for overwriting objects with the same name in the destination bucket

  Policy	Description
  Overwrite if source newer or different size	If a source object is not as large as or was last modified more recently than its paired destination object, the source object will overwrite the destination object.
  Never overwrite	The system always skips source objects and keeps their paired destination objects.
  Always overwrite	The system always allows source objects to overwrite their paired destination objects.