This topic describes how to migrate data from a self-managed MySQL database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS). In this scenario, the Express Connect circuit and the destination RDS instance are owned by different Alibaba Cloud accounts. DTS supports schema migration, full data migration, and incremental data migration. You can select all of the supported migration types to ensure service continuity.

Prerequisites

  • The version of the self-managed MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.
  • The available storage space of the ApsaraDB RDS for MySQL instance is larger than the total size of the data in the self-managed MySQL database.
  • The on-premises network to which the self-managed MySQL database belongs is connected to Alibaba Cloud VPC over Express Connect, VPN Gateway, or Smart Access Gateway. The Express Connect circuit and the destination RDS instance are owned by different Alibaba Cloud accounts.
    Note For more information, see Connect an on-premises database to Alibaba Cloud.

Background information

The data center that hosts your database is connected to Alibaba Cloud VPC over Express Connect, VPN Gateway, or Smart Access Gateway. You need to migrate data from the on-premises database to an ApsaraDB RDS for MySQL instance across different Alibaba Cloud accounts. The following figure shows the architecture for this scenario. Background information

Precautions

  • DTS uses read and write resources of the source and destination databases during full data migration. This may increase the loads of the database servers. 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.
  • DTS uses the ROUND(COLUMN,PRECISION) function to retrieve values from columns of the FLOAT or DOUBLE data type. If you do not specify a precision, DTS sets the precision for the FLOAT data type to 38 digits and the precision for the DOUBLE data type to 308 digits. You must check whether the precision settings meet your business requirements.
  • DTS automatically creates a destination database in the ApsaraDB RDS for MySQL instance. However, if the name of the source database is invalid, you must manually create a database in the ApsaraDB RDS for MySQL instance before you configure the data migration task.
    Note For more information about the naming conventions of ApsaraDB RDS for MySQL databases and how to create a database, see Create a database on an ApsaraDB RDS for MySQL instance.
  • 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 database will overwrite the data in the destination instance after the task is resumed.

Billing

Migration type Task 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. DTS supports schema migration for the following types of objects: table, view, trigger, stored procedure, and function.

    Note
    • During schema migration, DTS changes the value of the SECURITY attribute from DEFINER to INVOKER for views, stored procedures, and functions.
    • DTS does not migrate user information. Before a user can call views, stored procedures, and functions of the destination database, you must grant the read and write permissions to the user.
  • Full data migration
    DTS migrates historical data of the required objects from the self-managed MySQL database to the destination database in the ApsaraDB RDS for MySQL instance.
    Note During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the tablespace of the destination database is larger than that of the source database.
  • Incremental data migration

    After full data migration is complete, DTS retrieves binary log files from the self-managed MySQL database. Then, DTS synchronizes incremental data from the self-managed MySQL database to the destination ApsaraDB RDS for MySQL instance. Incremental data migration allows you to ensure service continuity when you migrate data from a self-managed MySQL database to Alibaba Cloud.

SQL operations that can be synchronized during incremental data migration

Operation type SQL statements
DML INSERT, UPDATE, DELETE, and REPLACE
DDL
  • ALTER TABLE and ALTER VIEW
  • CREATE FUNCTION, CREATE INDEX, CREATE PROCEDURE, CREATE TABLE, and CREATE VIEW
  • DROP INDEX and DROP TABLE
  • RENAME TABLE
  • TRUNCATE TABLE

Permissions required for database accounts

Database Schema migration Full data migration Incremental data migration
Self-managed MySQL database The SELECT permission The SELECT permission The REPLICATION SLAVE, REPLICATION CLIENT, SHOW VIEW, and SELECT permissions
ApsaraDB RDS for MySQL instance The read and write permissions The read and write permissions The read and write permissions

For information about how to create and authorize a database account, see the following topics:

Before you begin

  1. Create an account for a user-created MySQL database and configure binary logging.
  2. Log on to the Alibaba Cloud Management Console by using the Alibaba Cloud account that owns the Express Connect circuit. Authorize DTS to access the network that is connected over Express Connect. For more information, see Configure a route between DTS and Express Connect, VPN Gateway, or Smart Access Gateway.
  3. Create a RAM role and authorize the RAM role to access the resources of the Alibaba Cloud account. For more information, see Configure RAM authorization for data migration or synchronization from a user-created database in a VPC across different Alibaba Cloud accounts.

Procedure

  1. Use the Alibaba Cloud account that owns the destination RDS instance to 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 cluster resides.
    Select a region
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Select User-Created Database Connected over Express Connect, VPN Gateway, or Smart Access Gateway as the instance type. Then, click VPC of Another Alibaba Cloud Account next to the Peer VPC field.
    Select a VPC across Alibaba Cloud accounts
  6. Configure the source and destination databases.
    Configure the source and destination databases
    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 User-Created Database Connected over Express Connect, VPN Gateway, or Smart Access Gateway.
    Instance Region Select the region of the VPC that is connected to the self-managed MySQL database.
    Alibaba Cloud Account ID Enter the ID of the Alibaba Cloud account that owns the Express Connect circuit.
    Note To obtain the ID of the Alibaba Cloud account that owns the Express Connect circuit, you must log on to the Account Management console by using this account. The account ID is displayed on the Security Settings page.
    Obtain an Alibaba Cloud account ID
    Role Name Enter the name of the RAM role that you created earlier in Before you begin.
    Peer VPC Select the ID of the VPC that is connected to the self-managed MySQL database.
    Database Type Select MySQL.
    IP Address Enter the endpoint that is used to access the self-managed MySQL database.
    Port Number Enter the service port number of the self-managed MySQL database. The default port number is 3306.
    Database Account Enter the account of the self-managed MySQL database. 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 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.
    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.
    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 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 on an ApsaraDB RDS for MySQL instance.
    Note The Encryption parameter is available only for regions in mainland China and the China (Hong Kong) region.
  7. In the lower-right corner of the page, click Set Whitelist and Next.
    Note DTS adds the CIDR blocks of DTS servers to the whitelist of the destination ApsaraDB RDS for MySQL instance. This ensures that DTS servers can connect to the destination RDS instance.
  8. Select the migration types and the objects to be migrated.
    Select the migration types and the objects to be migrated
    Setting Description
    Select the migration types
    • To perform only full 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, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
    Select the objects to be migrated

    Select one or more objects from the Available section and click the Rightwards arrow icon to move the objects to the Selected section.

    Note
    • You can select columns, tables, or databases as the objects to be migrated.
    • By default, 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 rename the objects that are migrated to the destination database. For more information, see Object name mapping.
    • If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
    Specify whether to rename objects You can use the object name mapping feature to rename the objects that are migrated to the destination instance. For more information, see Object name mapping.
    Specify the retry time for failed connections to the source or destination database By default, if DTS fails to connect to the source or destination database, DTS retries within the next 720 minutes (12 hours). You can specify the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
    Specify whether to copy temporary tables to the destination database when DMS performs online DDL operations on the source table If you use Data Management (DMS) to perform online DDL operations on the source database, you can specify whether to migrate temporary tables generated by online DDL operations.
    • Yes: DTS migrates the data of temporary tables generated by online DDL operations.
      Note If online DDL operations generate a large amount of data, the data migration task may be delayed.
    • No: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL data of the source database is migrated.
      Note If you select No, the tables in the destination database may be locked.
  9. 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, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  10. After the task passes the precheck, click Next.
  11. In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.
  12. Click Buy and Start to start the data migration task.
    • Schema migration and full data migration

      We recommend that you do not manually stop the task during full data migration. Otherwise, the data migrated to the destination database will be incomplete. You can wait until the data migration task automatically stops.

    • Schema migration, full data migration, and incremental data migration

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

      Notice We recommend that you select an appropriate time to manually stop the data migration task. For example, you can stop the task during off-peak hours or before you switch your workloads to the destination cluster.
      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. Wait until the status of incremental data migration changes to The migration task is not delayed again. Then, manually stop the migration task. Stop a task during incremental data migration
  13. Switch your workloads to the destination ApsaraDB RDS for MySQL instance.