This topic describes how to migrate data between ApsaraDB RDS for MySQL instances by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. When you configure a migration task, you can select all of these supported migration types. This allows you to migrate data without causing service interruptions to your application.

Prerequisites

The source and destination RDS instances use the same database engines.

Precautions

  • DTS uses read and write resources of the source and destination databases during full data migration. This may increase the load of the database server. If the database performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source database, the tables have no primary keys, or a deadlock occurs in the destination database. Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. For example, you can migrate data when the CPU utilization of the source and destination databases is less than 30%.
  • The tables to be migrated in the source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
  • To ensure data consistency, do not write data to the source RDS instance during full data migration.
  • If a data migration task fails, DTS automatically resumes the task. Before you switch your workloads to the destination instance, stop or release the data migration task. Otherwise, the data in the source instance will overwrite the data in the destination instance after the task is resumed.

Billing

Migration type Instance configuration fee Internet traffic fee
Schema migration and full data migration Free of charge Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Pricing.
Incremental data migration Charged. For more information, see Pricing.

Migration types

  • Schema migration

    DTS migrates the schemas of the required objects to the destination instance.

  • Full data migration

    DTS migrates historical data of the required objects from the source RDS instance to the destination RDS instance.

  • Incremental data migration

    After full data migration is complete, DTS synchronizes incremental data from the source RDS instance to the destination RDS instance. Incremental data migration allows you to ensure service continuity when you migrate data between RDS instances.

Permissions required for database accounts

Database Schema migration Full data migration Incremental data migration
Source RDS instance The read/write permissions The read/write permissions The read/write permissions
Destination RDS instance The read/write permissions The read/write permissions The read/write permissions

Procedure

  1. Log on to the DTS console.
  2. In the left-side navigation pane, click Data Migration.
  3. At the top of the Migration Tasks page, select the region where the destination RDS instance resides.Select a region
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Configure the source and destination databases for the data migration task. Migrate data between RDS instances
    Section Parameter Description
    N/A Task Name DTS automatically generates a task name. We recommend that you specify an informative name for easy identification. You do not need to use a unique task name.
    Source Database Instance Type Select RDS Instance.
    Instance Region Select the region where the source RDS instance resides.
    RDS Instance ID Select the ID of the source RDS instance.
    Note The source and destination RDS instances can be the same or different. You can use DTS to migrate data within an RDS instance or between two RDS instances.
    Database Name Enter the name of the source database in the ApsaraDB RDS for PostgreSQL instance.
    Note This parameter is required only if the database engine of the RDS instance is PostgreSQL.
    Database Account Enter the database account of the source RDS instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password Enter the password of the source database account.
    Note After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the source database parameters based on the check results.
    Encryption Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the RDS instance before you configure the data migration task. For more information, see Configure SSL encryption for an RDS MySQL instance.
    Note

    This parameter is required only if the database engine of the RDS instance is MySQL.

    The Encryption parameter is available only for regions in mainland China and the China (Hong Kong) region.

    Destination Database Instance Type Select RDS Instance.
    Instance Region Select the region where the destination RDS instance resides.
    RDS Instance ID Select the ID of the destination RDS instance.
    Note The source and destination RDS instances can be the same or different. You can use DTS to migrate data within an RDS instance or between two RDS instances.
    Database Name Enter the name of the destination database in the ApsaraDB RDS for PostgreSQL instance. The name of the destination database can be different from the name of the source database.
    Note This parameter is required only if the database engine of the RDS instance is PostgreSQL.
    Database Account Enter the database account of the destination RDS instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password Enter the password of the destination database account.
    Note After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the destination database parameters based on the check results.
    Encryption Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the RDS instance before you configure the data migration task. For more information, see Configure SSL encryption for an RDS MySQL instance.
    Note This parameter is required only if the database engine of the RDS instance is MySQL.

    The Encryption parameter is available only for regions in mainland China and the China (Hong Kong) region.

  6. In the lower-right corner of the page, click Set Whitelist and Next.
    Note DTS adds the CIDR blocks of DTS servers to the whitelists of the source and destination RDS instances. This ensures that DTS servers can connect to the source and destination RDS instances.
  7. Select the migration types and objects to be migrated. Select the migration types and objects to be migrated
    Parameter Description
    Migration Types

    Select the migration types based on your business requirements. The migration types must be supported by the database engine.

    • To perform only full data migration, select Schema Migration and Full Data Migration.
    • To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.
    Note If Incremental Data Migration is not selected, do not write data to the source RDS instance during full data migration. This ensures data consistency between the source and destination instances.
    Available

    Select objects from the Available section and click the Right arrow icon to move the objects to the Selected section.

    Note
    • You can select databases, tables, or columns as the objects to be migrated.
    • After an object is migrated to the destination database, the name of the object remains unchanged. You can use the object name mapping feature to change the names of the objects that are migrated to the destination database. For more information, see Object name mapping.
    • If you use the object name mapping feature on an object, other objects that are dependent on the object may fail to be migrated.
  8. In the lower-right corner of the page, click Precheck.
    Note
    • Before you can start the data migration task, a precheck is performed. You can start the data migration task only after the task passes the precheck.
    • If the task fails to pass the precheck, click the Info icon icon next to each failed item to view details. Troubleshoot the issues based on the causes and run the precheck again.
  9. After the task passes the precheck, click Next.
  10. In the Confirm Settings dialog box, specify the Channel Specification and select Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the migration task.
    • Full data migration

      Do not manually stop a task during full data migration. Otherwise, data migrated to the destination database will be incomplete. Wait until the migration task automatically stops.

    • Incremental data migration

      An incremental data migration task does not automatically stop. You must manually stop the migration task.

      Note Select an appropriate time to manually stop the migration task. For example, you can stop the migration task during off-peak hours or before you switch your workloads to the destination instance.
      1. Wait until Incremental Data Migration and The migration task is not delayed appear in the progress bar of the migration task. Then, stop writing data to the source database for a few minutes. The delay time of incremental data migration may be displayed in the progress bar.
      2. After the status of incremental data migration changes to The migration task is not delayed, manually stop the migration task.The migration task is not delayed