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

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.

• 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 overwrites the data in the destination instance after the task is resumed.

Billing rules

Migration types

• Schema migration

  DTS migrates the schemas of required objects to the destination database. DTS supports schema migration for the following types of objects: table, view, trigger, stored procedure, and function. DTS does not support schema migration for events.

  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. To call a view, stored procedure, or function of the destination database, you must grant read and write permissions to INVOKER.

• Full data migration

  DTS migrates the historical data of required objects to the destination database.

  Note

  • During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the size of used tablespace of the destination database is larger than that of the source database.

  • To ensure successful data migration, we recommend that you do not perform DDL operations on the source database during full data migration.

• Incremental data migration

  After full data migration is complete, DTS retrieves binary log files from the source database, and migrates incremental data to the destination database in real time.

SQL operations that can be synchronized during incremental data migration

Permissions required for database accounts

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

• ApsaraDB RDS for MariaDB instances:Create an account on an ApsaraDB RDS for MariaDB instance.

• ApsaraDB RDS for MySQL instances:Create an account on an ApsaraDB RDS for MySQL instance and Modify the permissions of a standard account for an ApsaraDB RDS for MySQL instance.

Procedure

1. Log on to the DTS console.

   Note

   If you are redirected to the Data Management (DMS) console, you can click the icon in the to go to the previous version of 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.

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

5. Configure the source and destination databases.

   

   Section	Parameter	Description
   N/A	Task Name	The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Instance Type	Select RDS Instance.
   	Instance Region	The region where the source ApsaraDB RDS for MariaDB instance resides.
   	RDS Instance ID	The ID of the source ApsaraDB RDS for MariaDB instance.
   	Database Account	The database account of the source ApsaraDB RDS for MariaDB instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	The password of the database account. After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. Note If the specified parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed. Modify the source database parameters based on the check results.
   Destination Instance Details	Instance Type	Select RDS Instance.
   	Instance Region	The region where the destination ApsaraDB RDS for MySQL instance resides.
   	RDS Instance ID	The ID of the destination ApsaraDB RDS for MySQL instance.
   	Database Account	The database account of the destination ApsaraDB RDS for MySQL instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	The password of the database account. After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. Note If the specified parameters are valid, the Passed message is displayed. If the Failed message is displayed, 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 ApsaraDB RDS for MySQL instance before you configure the data migration task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance. Note The Encryption parameter is available only for regions in the Chinese mainland and the China (Hong Kong) region.

6. In the lower-right corner of the page, click Set Whitelist and Next.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhance the security of your username and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

7. Select migration types and the objects to migrate.

   

   Setting	Description
   Select migration types	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. Important If Incremental Data Migration is not selected, we recommend that you do not write data to the source database during full data migration. This ensures data consistency between the source and destination databases.
   Select the objects that you want to migrate	Select one or more objects from the Available section and click the icon to add the objects to the Selected section. Important 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 database. For more information, see Object name mapping.
   Specify the retry time range 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 range based on your business requirements. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note Within the time range in which DTS attempts to reconnect to the source and destination databases, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at the earliest opportunity after the source and destination databases 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 DMS to perform online DDL operations on the source database, you can specify whether to migrate temporary tables generated by online DDL operations. Valid values: 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 take an extended period of time to complete. 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.

8. In the lower-right corner of the page, click Precheck.

   Note

   • Before you can start the data migration task, DTS performs a precheck. 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 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.

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

10. In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.

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

Stop the data 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

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

  1. Wait until the task progress bar shows Incremental Data Migration and The migration task is not delayed. Then, stop writing data to the source database for a few minutes. In some cases, the progress bar shows the delay time of incremental data migration.
  2. After the status of incremental data migration changes to The migration task is not delayed, manually stop the migration task.