> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nebius.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Object key prefixes in data transfers

By default, all source objects are transferred in a data transfer, and their [keys](/object-storage/overview#keys-prefixes-and-object-hierarchy) are unchanged in the destination. You can optionally use source and destination prefixes to change this behavior:

* *Source prefix* filters objects in the source bucket.
* *Destination prefix* is added to keys of all transferred objects.

> For example, if the source prefix is `test_dir/` and the destination prefix is `migration/`, the data transfer only works with source objects that have keys starting with `test_dir/`. In the destination, the data transfer replaces the `test_dir/` prefix in object keys with `migration/`. A source object named `test_dir/somefile.txt` becomes `migration/somefile.txt` in the destination.

You can specify prefixes when you [create](/object-storage/transfer/launch) or [modify](/object-storage/transfer/manage) a data transfer:

<Tabs>
  <Tab title="Web console">
    In the [web console](https://console.nebius.com/datatransfer), append prefixes to the names of the source and destination buckets (for example, `mybucket/test_dir/`).
  </Tab>

  <Tab title="CLI">
    Set the `.spec.source.prefix` and `.spec.destination.prefix` parameters in your configuration file:

    ```json theme={null}
    {
      "spec": {
        "source": {
          "prefix": "test_dir/"
        },
        "destination": {
          "prefix": "migration/"
        }
      }
    }
    ```
  </Tab>

  <Tab title="Terraform">
    Use the `prefix` argument in the `source` and `destination` blocks:

    ```hcl theme={null}
    resource "nebius_storage_v1_transfer" "example" {
      source {
        prefix = "test_dir/"
        # Other source parameters
      }
      destination {
        prefix = "migration/"
        # Other destination parameters
      }
      # Other parameters
    }
    ```
  </Tab>
</Tabs>