This topic describes the usage notes and procedure for data migration.

Usage notes

When you run an online migration job, take note of the following items:
  • A migration job occupies the network resources of the source and destination data addresses. To ensure business continuity, we recommend that you specify a rate limit for your migration job or run your migration job during off-peak hours.
  • Before an online migration job starts, the system checks the files at the source data address and the destination data address. If the source and destination have files with the same name, and the last modification time of the source file is later than the last modification time of the destination file, the destination file is overwritten. If both files are important and contain different information, we recommend that you change the name of one file or back up the destination file.
  • If symbolic links exist at the source data address, the files to which the symbolic links point are migrated to the destination data address. The migrated files are named based on the symbolic links. For example, a symbolic link named a exists at Source Data Address A. The file to which the symbolic link points is b.jpg. b.jpg is migrated to the destination data address and renamed a. For more information, see Configure symbolic links.
    Note If the objects to be migrated contain symbolic links, the migration workload may be greater than estimated, and the migration may continue even if the displayed migration progress reaches 100%. The migration duration varies based on the actual migration workload.
  • Data Online Migration allows you to migrate only the data of a single bucket per job. You cannot migrate all data that belongs to your account at a time.
  • Make sure that you verify the migrated data at the destination data address after the migration job is complete to ensure that the migrated data is correct. If you delete the relevant data at the source data address before you verify the migrated data at the destination data address, you are liable for the losses and consequences caused by any data loss.

Step 1: Create a source data address

  1. Log on to the Alibaba Cloud Data Transport console.
  2. In the left-side navigation pane, choose Data Online Migration > Data Address. On the page that appears, click Create Data Address.
  3. In the Create Data Address panel, set the parameters and click OK. The following table describes the parameters.
    Parameter Required Description
    Data Type Yes Select OSS.
    Data Name Yes Enter a name. The name must be 3 to 63 characters in length. The name cannot contain special characters, except for hyphens (-) and underscores (_).
    Data Region Yes Select the region in which the source data address resides. Example: China (Hangzhou).
    Enable Transfer Acceleration No If you want to use Data Online Migration together with the transfer acceleration feature of Object Storage Service (OSS), enable the transfer acceleration feature for buckets. The transfer acceleration feature takes effect within 30 minutes after it is enabled. After you enable the feature, wait for 30 minutes before you create a migration job.
    Notice If you use the transfer acceleration feature to access OSS buckets, you are charged additional transfer acceleration fees. For more information, see Transfer acceleration.
    OSS Endpoint Yes Select an endpoint in the region in which your data is stored. For more information, see Regions and endpoints.
    • http://oss-cn-endpoint.aliyuncs.com: specifies that an HTTP-based endpoint is used to access OSS over the Internet.
    • https://oss-cn-endpoint.aliyuncs.com: specifies that an HTTPS-based endpoint is used to access OSS over the Internet.
    • http://oss-cn-qingdao-internal.aliyuncs.com: specifies that a private HTTP-based endpoint is used to access OSS.
    • https://oss-cn-qingdao-internal.aliyuncs.com: specifies that a private HTTPS-based endpoint is used to access OSS.
    Notice For example, a private OSS endpoint is used as the source data address when you create a migration job. In this case, the destination data address must be an Apsara File Storage NAS or OSS data address in the same region.
    Access Key Id Yes Specify the AccessKey pair that you want to use to migrate data. For more information, see Before you begin.
    Note If you want to migrate data across accounts, you must specify the AccessKey pair of the source Alibaba Cloud account.
    Access Key Secret Yes
    OSS Bucket Yes Select the bucket in which the data that you want to migrate is stored.
    OSS Prefix Yes An OSS prefix cannot start with a forward slash (/). An OSS prefix must end with a forward slash (/). For example, you can specify data/to/oss/ as the OSS prefix.
  4. Optional: If the system prompts that this feature is in public preview, click Application to apply to use this feature.
  5. Optional: Enter the required information and submit the application for the feature in public preview. After the application is approved, the system sends a text message to notify you.

Step 2: Create a destination data address

  1. In the left-side navigation pane, choose Data Online Migration > Data Address. On the page that appears, click Create Data Address.
  2. In the Create Data Address panel, set the parameters and click OK. The following table describes the parameters.
    Parameter Required Description
    Data Type Yes Select OSS.
    Data Name Yes Enter a name. The name must be 3 to 63 characters in length. The name cannot contain special characters, except for hyphens (-) and underscores (_).
    Data Region Yes Select the region in which the destination data address resides.
    Enable Transfer Acceleration No If you want to use Data Online Migration together with the transfer acceleration feature of OSS, enable the transfer acceleration feature for buckets. The transfer acceleration feature takes effect within 30 minutes after it is enabled. After you enable the feature, wait for 30 minutes before you create a migration job.
    Notice If you use the transfer acceleration feature to access OSS buckets, you are charged additional transfer acceleration fees. For more information, see Transfer acceleration.
    OSS Endpoint Yes Select an endpoint in the region in which your data is stored. For more information, see Regions and endpoints.
    Access Key Id Yes Specify the AccessKey pair that you want to use to migrate data. For more information, see Create a Resource Access Management (RAM) user and grant required permissions to the RAM user..
    Note If you want to migrate data across accounts, you must specify the AccessKey pair of the destination Alibaba Cloud account.
    Access Key Secret Yes
    OSS Bucket Yes Select a bucket to store the migrated data.
    OSS Prefix Yes The value cannot start with a forward slash (/). The value must end with a forward slash (/). For example, you can specify data/to/oss/ as the OSS prefix. If you want to migrate data to the root directory of the specified bucket, do not set this parameter.

Step 3: Create a migration job

  1. In the left-side navigation pane, choose Data Online Migration > Migration Jobs. On the page that appears, click Create Job.
  2. In the Create Job panel, read the terms of the migration service and select I agree to the above terms and activate the Data Transport service.. Then, click Next.
  3. In the Fee Reminder message, click Yes, Go Ahead.
  4. In the Job Config step, set the parameters and click Next. The following table describes the parameters.
    Parameter Required Description
    Job Name Yes Enter a job name. The name must be 3 to 63 characters in length and can contain only lowercase letters, digits, and hyphens (-). It cannot start or end with a hyphen (-).
    Source Data Address Yes Select the source data address that you created.
    Destination Data Address Yes Select the destination data address that you created.
    Specified Directory No Specify directories in which the files and subdirectories are migrated or not migrated.
    • Do not filter: All data from the source data address is migrated.
    • Exclude: The files and subdirectories in the specified directories are not migrated.
    • Contain: Only the files and subdirectories in the specified directories are migrated.
    Note
    • Before you set the Specified Directory parameter, you must configure a whitelist. For more information, see Advanced features.
    • A directory name cannot start with a forward slash (/) or a backslash (\), and cannot contain double forward slashes (//), double periods (..), or double quotation marks ("). The character string that consists of all the specified directory names cannot exceed 10 KB in length.
    • A directory name must end with a forward slash (/). For example, you can specify docs/ as the directory name.
    • You can specify up to 20 directories of the Exclude or Contain type.
    Migration Type Yes Select the data migration mode.
    • Full: The system migrates all data from the source data address to the destination data address. You must set the Start Time Point of File parameter. The system migrates all data whose last modification time is later than the specified time. After all data is migrated, the migration job ends.

      If you change the data at the source data address after the migration job is complete, you can submit another job to migrate all data. In this case, the system migrates only the changed data.

    • Incremental: The system runs a migration job based on the values that you specified for the Migration Interval and Migration Times parameters.
      • You must set the Start Time Point of File parameter. During the first migration, the system migrates all data whose last modification time is later than the specified time. After the first migration job is complete, incremental migration jobs are performed based on the value that you specified for the Migration Interval parameter. For each incremental migration, the system migrates only the data that is created or modified after the previous migration starts and before the current migration starts.
      • If you set the Migration Times parameter to N, a full migration job is performed once and then the incremental migration job is performed (N - 1) times.

        For example, the current time is 08:00, March 10, 2019 and you set the Migration Interval parameter to 1, the Migration Times parameter to 5, and the Start Time Point of File parameter to 08:00, March 5, 2019. When the first migration starts, the system migrates all files whose last modification time is between 08:00, March 5, 2019 and 08:00, March 10, 2019. In this example, the first migration requires one hour to complete and the second migration starts at 10:00, March 10, 2019. The duration from 08:00 to 10:00 consists of one hour for the first migration process and one hour for the migration interval. During the second migration, the system migrates the files whose last modification time is between 08:00, March 10, 2019 and 10:00, March 10, 2019. The migration job consists of one full migration and four incremental migrations.

    Notice Before you start a full or incremental migration job, the system compares the files at the source data address with the files at the destination data address. If a source file has the same name as a destination file, the destination file is overwritten when one of the following conditions is met:
    • The Content-Type values of the source file and the destination file are different.
    • The last modification time of the source file is later than that of the destination file.
    • The size of the source file is different from that of the destination file.
    Start Time Point of File Yes Specify a time to filter data to be migrated. Data will be migrated if it is created or modified after the specified time.
    • All: All files are migrated.
    • Assign: Only the files that are created or modified after the specified time are migrated.

      For example, if you set the time to 08:00:00, November 1, 2018, only the files that are created or modified after 08:00:00, November 1, 2018 are migrated.

    Migration Interval This parameter is required if you set the Migration Type parameter to Incremental. The default value is 1 and the maximum value is 24. Unit: hours.
    Migration Times This parameter is required if you set the Migration Type parameter to Incremental. The default value is 1 and the maximum value is 30.
    File Overwrite Method Yes The method that is used to process the source file whose name is the same as that of a destination file. Valid values:
    • LastModified: If a source file has the same name as a destination file, the system compares the last modification time that is indicated by the LastModified property of the files.
      • If the last modification time of the source file is later than that of the destination file, the source file is migrated and the destination file is overwritten.
      • If the last modification time of the source file is earlier than that of the destination file, the source file is not migrated and the destination file is retained.
      • If the two files have the same last modification time, the system checks the values of the Size and Content-Type properties of the files.

        If the files have the same Size and Content-Type values, the source file is not migrated. If the two files have different values of at least one property, the source file is migrated and the destination file is overwritten.

    • Condition: If a source file has the same name as a destination file, the system compares the values of the LastModified, Size, and Content-Type properties of the two files.
      • If all property values of the two files are the same, the source file is not migrated.
      • If the two files have different values of at least one property, the source file is migrated and the destination file is overwritten.
    • All: If a source file has the same name as a destination file, the system performs no comparison and directly overwrites the destination file with the source file.
    • No: If a source file has the same name as a destination file, the system performs no comparison and directly skips the source file in the migration.
  5. In the Performance step, go to the Data Prediction section and set the Data Size and File Count parameters.
    Note To ensure a successful migration job, we recommend that you estimate the amount of data to be migrated as accurately as possible. For more information, see Before you begin.
  6. Optional:In the Performance step, go to the Flow Control section, set the Time Range and Max Flow(MB/s) parameters, and then click Add.
    Note To ensure business continuity, we recommend that you set the Time Range and Max Flow(MB/s) parameters based on the workloads of peak hours and off-peak hours.
  7. Click Create and wait until the migration task is complete.