How Does Migration Affect My Source Data? What Are the Impacts on Migration If the Source Data Changes?

No Impact on Source Data

• Data in the source bucket is not modified during the migration.
• Data in the source bucket is not locked during the migration.
• Data in the source bucket is not deleted after the migration.

Impacts on Services on Source Platforms

• A fast migration may generate additional fees, for instance, CDN fees, or affect other services on the source platform. You are advised to limit the migration speed based on your service requirements. For details, see "Traffic Limit" described in Creating a Migration Task.
• You may be unaware of the migration fees generated on the source platform, and this may cause your account to fall into arrears, which can affect your services. For details about the billing mode of OMS, see Pricing Details.

Impacts Caused by Source Data Changes

• Data addition

  By default, objects are migrated based on the selected prefixes, in alphabetical order. During the migration, if any data is added to the source bucket before OMS finishes listing source objects, the new data will be migrated, but data added after that point will not.

• Data modification
  To ensure reliability, OMS migrates large objects in parts and, after the migration, compares the sizes and modification times of the source object with the paired destination object. If a part is modified during the migration and both of the following conditions are met, data inconsistency occurs:

  • The object size is the same before and after the modification.
  • The source object is last modified more recently than the destination object.

• Data deletion

  After migration, if some data in the source bucket is deleted, the corresponding data in the destination bucket will not be affected.