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Version: 2.3

Configure an Alibaba Cloud Object Storage Service target

You can migrate data to an Alibaba Cloud Object Storage Service (OSS) bucket by configuring one as a target filesystem.

Follow these steps to create an Alibaba Cloud OSS target:


Alibaba Cloud OSS buckets created with the hierarchical namespace option are not supported.


You need the following:

  • An Alibaba Cloud OSS bucket.

  • Authentication details for your bucket. See below for more information.

Configure an Alibaba Cloud OSS target filesystem in the UI

  1. From the Dashboard, select an instance under Instances.

  2. In the Filesystems & Agents menu, select Filesystems.

  3. Select Add target filesystem.

  4. Enter the following details:

    • Filesystem Type - The type of filesystem target. Select Alibaba Object Storage.
    • Display Name - Enter a name for your target filesystem.
    • Access Key - Enter the Alibaba bucket access key. For example, RANDOMSTRINGACCESSKEY.
    • Secret Key - Enter the secret key that corresponds with your Access Key. For example, RANDOMSTRINGPASSWORD.
    • Bucket Name - The reference name of your Alibaba Cloud OSS bucket.
    • Endpoint - The Alibaba Cloud OSS endpoint for your bucket.
    • S3 Properties - Add optional properties to your target as key-value pairs.
  5. Select Save. You can now use your Alibaba Cloud OSS target in data migrations.

S3A properties

Enter additional properties for Alibaba Cloud OSS filesystems by adding them as key/value pairs in the UI or as a comma-separated key-value pair list with the --properties parameter in the CLI. You can overwrite default property values or add new properties.

Default properties

These properties are defined by default when you add an Alibaba Cloud OSS filesystem. Overwrite them by specifying their keys with new values in key-value pairs.

  • fs.s3a.impl (default org.apache.hadoop.fs.s3a.S3AFileSystem): The implementation class of the S3A filesystem.
  • fs.AbstractFileSystem.s3a.impl (default org.apache.hadoop.fs.s3a.S3A): The implementation class of the S3A abstract filesystem.
  • fs.s3a.user.agent.prefix (default APN/1.0 WANdisco/1.0 LiveDataMigrator/1.11.6): Sets a custom value that will be prepended to the user-agent header sent in HTTP requests to the S3 backend by the S3A filesystem.
  • fs.s3a.impl.disable.cache (default true): Disables the S3 filesystem cache when set to 'true'.
  • hadoop.tmp.dir (default tmp): The parent directory for other temporary directories.
  • fs.s3a.connection.maximum (default 120) Defines the maximum number of simultaneous connections to the S3 filesystem.
  • fs.s3a.threads.max (default 150): Defines the total number of threads made available for data uploads or any other queued filesystem operation.
  • (default 60): Defines the number of operations that can be queued for execution at a time.
  • fs.s3a.healthcheck (Default true): Allows you to switch the health check off by changing the value from true to false. This option is useful for setting up Data Migrator while cloud services are offline. If you disable the check, it's harder to diagnose any issues with the S3A configuration.

Additional properties

These additional properties are not defined by default. Add more properties by specifying their key-value pairs.

  • (default disk): Defines how the filesystem buffers the upload.
  • (default 8): Defines how many blocks a single output stream can have uploading or queued at a given time.
  • fs.s3a.block.size (default 32M): Defines the maximum size of blocks during file transfer. Use the suffix K, M, G, T, or P to scale the value in kilobytes, megabytes, gigabytes, terabytes, or petabytes, respectively.
  • fs.s3a.buffer.dir (default tmp): Defines the directory used by disk buffering.

Find an additional list of S3A properties in the S3A documentation.

Upload buffering

Migrations using an S3 target destination buffer all uploads. By default, the buffering occurs on the local disk of the same system on which Data Migrator is running. Uploads are buffered to the /tmp directory.

Data Migrator automatically deletes the temporary buffering files once they are no longer needed.

To use a different type of buffering, change the property Enter one of the following values:

Buffering optionDetailsProperty value
Array bufferBuffers the uploaded data in memory instead of on the disk, using the Java heap.array
Byte bufferBuffers the uploaded data in memory instead of on the disk, but doesn't use the Java heap.bytebuffer
Disk bufferingThe default option. This property buffers the upload to the disk.disk

Both the array and bytebuffer options may consume large amounts of memory. To avoid using a lot of memory and fine-tune your migrations, use properties such as


If you run out of disk space on which to buffer the migration, the migration will stall with a series of errors. To avoid this, ensure the filesystem containing the directory used for buffering (/tmp by default) has enough remaining space to facilitate the transfer.

Next steps

If you haven't already, configure a source filesystem from which to migrate data. Then, you can create a migration to migrate data to your new Alibaba Object Storage target.