Data Transmission Service:Migrate data from RDS for MariaDB to RDS for MySQL

Precautions

• During a full data migration, DTS consumes read and write resources on the source and destination databases, increasing their load. If your databases have poor performance, low specifications, or high workloads (for example, if the source database has many slow SQL queries or tables without primary keys, or if deadlocks occur in the destination database), the increased load can strain your databases or even cause service interruptions. Perform the data migration during off-peak hours, such as when the CPU utilization of both databases is below 30%.

• If a source table lacks a primary key or a unique constraint and contains non-unique data, duplicate data may be created in the destination database.

• If a data migration task fails, DTS automatically resumes it. Before you switch services to the destination instance, stop or release the migration task to prevent it from overwriting data in the destination instance with data from the source database.

Billing

Migration types

• Schema migration

  DTS migrates the schemas of the selected objects to the destination database. Schema migration is supported for tables, views, triggers, stored procedures, and functions, but not for events.

  Note

  • During schema migration, DTS changes the DEFINER of views, stored procedures, and functions to INVOKER.

  • Because DTS does not migrate user information, grant the invoker the required read and write permissions to call these objects in the destination database.

• Full data migration

  DTS migrates all existing data from the selected objects to the destination database.

  Note

  • During full data migration, concurrent INSERT operations can cause table fragmentation in the destination database. As a result, the table space in the destination database may be larger than that in the source database after migration.

  • To ensure a successful migration, do not perform DDL operations on the source database during full data migration.

• Incremental data migration

  After full data migration, DTS reads the binlog of the source database and migrates subsequent data changes to the destination database in real time.

SQL operations for incremental migration

Database account permissions

To create a database account and grant permissions:

• For an ApsaraDB RDS for MariaDB instance, see Create an account.

• For an ApsaraDB RDS for MySQL instance, see Create an account and Modify account permissions.

Procedure

1. Log on to the DTS console.

   Note

   If you are automatically redirected to the Data Management (DMS) console, you can click the icon in the lower-right corner and then click to return to the classic DTS console.

2. In the left-side navigation pane, click Data Migration.

3. At the top of the Migration Tasks page, select the region of the destination cluster.

4. In the upper-right corner of the page, click Create Data Migration Task.

5. Configure the connection settings for the source and destination databases.

   Section	Parameter	Description
   N/A	Task name	DTS automatically generates a task name. Use a descriptive name to easily identify the task. The name does not need to be unique.
   Source Database	Instance type	Select RDS Instance.
   	Instance region	Select the region where the source ApsaraDB RDS for MariaDB instance resides.
   	RDS instance ID	Select the ID of the source ApsaraDB RDS for MariaDB instance.
   	Database account	Enter the database account of the source ApsaraDB RDS for MariaDB instance. For information about the required permissions, see Database account permissions.
   	Database password	Enter the password for the database account. After you enter the source database information, you can click Test Connectivity next to Database Password to verify that the entered information is correct. Note If the information is entered correctly, a Passed message is displayed. If a Failed message is displayed, click Diagnose after Failed and follow the prompts to adjust the source database information.
   Destination Database	Instance type	Select RDS Instance.
   	Instance region	Select the region where the destination ApsaraDB RDS for MySQL instance resides.
   	RDS instance ID	Select the ID of the destination ApsaraDB RDS for MySQL instance.
   	Database account	Enter the database account of the destination ApsaraDB RDS for MySQL instance. For information about the required permissions, see Database account permissions.
   	Database password	Enter the password for the database account. After you enter the destination database information, you can click Test Connectivity after Database Password to verify that the entered information is correct. Note If the information is entered correctly, a Passed message is displayed. If a Failed message is displayed, click Diagnose after Failed and adjust the destination database information based on the prompts.
   	Connection method	Select Non-encrypted or SSL-encrypted as required. If you select SSL-encrypted, you must first enable SSL encryption for the ApsaraDB RDS for MySQL instance. For more information, see Configure SSL encryption. Note The Encryption parameter is available only in the Chinese mainland and China (Hong Kong) regions.

6. After you complete the configurations, click Set Whitelist and Next.

   If the source or destination is an Alibaba Cloud database instance, such as ApsaraDB for MySQL or ApsaraDB for MongoDB, DTS automatically adds the IP addresses of its servers in the corresponding region to the instance's whitelist. If the source or destination is a self-managed database on an ECS instance, DTS automatically adds its IP addresses to the security rules of the ECS instance. You must also ensure that the self-managed database does not restrict access from the ECS instance. If the database is a cluster deployed across multiple ECS instances, you must manually add the DTS IP addresses to the security rules for each ECS instance. If the source or destination is a database in an on-premises data center or on another cloud, you must manually add the DTS IP addresses for the corresponding region to allow access from DTS servers. For a list of DTS server IP addresses, see DTS server IP addresses.

   Warning

   Adding the public CIDR blocks of DTS servers, whether automatically or manually, may introduce security risks. By using this product, you acknowledge and accept these potential risks. You are responsible for implementing basic security measures, including but not limited to using strong passwords, restricting open ports, using authentication for internal API calls, regularly reviewing and restricting unnecessary network segments, or connecting through private networks such as Express Connect, VPN Gateway, or Smart Access Gateway.

7. Select the migration types and the objects to migrate.

   Setting	Description
   Migration types	To perform only a full migration, select both Schema Migration and Full Data Migration. To perform a zero-downtime migration, select Schema Migration, Full Data Migration, and Incremental Data Migration. Important If you do not select Incremental Data Migration, do not write new data to the source database during the full data migration to ensure data consistency.
   Migration objects	In the Available box, click the objects that you want to migrate and click the icon to move them to the Selected Objects box. Important You can select objects to migrate at the database, table, and column levels. By default, object names are retained after migration. If you need to rename an object in the destination database, use the object name mapping feature. For more information, see Object name mapping. If you rename an object by using the object name mapping feature, other objects that depend on it may fail to migrate.
   Object name mapping	If you need to rename a migrated object in the destination instance, use the object name mapping feature. For more information, see Object name mapping.
   Connection retry duration	If a connection to the source or destination database is interrupted, DTS retries to connect for a default of 720 minutes (12 hours). You can customize this duration. If DTS successfully reconnects within the specified time, the migration task resumes. Otherwise, the task fails. Note You are charged for the DTS instance while it attempts to reconnect. To avoid unnecessary charges, set an appropriate retry duration or release the DTS instance promptly if the source and destination databases are released.
   Replicate temporary tables created during online DDL operations in DMS	If you use Data Management (DMS) to perform online DDL operations on the source database, you can choose whether to migrate the temporary tables that are generated. Yes: Migrates the data in the temporary tables that are generated by online DDL operations. Note If a large amount of temporary table data is generated by online DDL operations, the migration task may experience high latency. No: Does not migrate the data in the temporary tables. Only the original DDL data from the source database is migrated. Note This option may cause table locks on the destination database.

8. After you complete the configuration, click Precheck and Start in the lower-right corner of the page.

   Note

   • Before the migration task starts, DTS runs a precheck. The task can start only after it passes the precheck.

   • If the precheck fails, click the icon next to the failed item to view details.

     • Fix the issues as prompted and run the precheck again.

     • If you do not need to fix the warning items, you can select Ignore and then click Ignore Warnings and Rerun Precheck to run the precheck again.

9. After the task passes the precheck, click Next.

10. In the Confirm Settings dialog box that appears, select a Instance Class and select the Data Transmission Service (pay-as-you-go) Service Terms checkbox.

11. Click Buy and Start to start the migration task.

Stop the migration task

• Full data migration

  Do not manually stop a task during full data migration. Otherwise, the system may fail to migrate all data. Wait until the migration task automatically ends.

• Incremental data migration

  This type of task does not stop automatically; you must stop it manually.

  1. Wait until the task enters the Incremental Data Migration stage with a Undelayed status. Then, stop writes to the source database for a few minutes. During this period, the Incremental Data Migration status might report a latency.
  2. Wait for the Incremental Data Migration status to return to Undelayed. Once this is confirmed in the list, select the task's checkbox and click the StopEnd button in the batch operations bar at the bottom.