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

Usage notes

• 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 database naming conventions of ApsaraDB RDS for MySQL databases and how to create a database, see Create a database for 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 overwrites the data in the destination instance after the task is resumed.

Billing

Migration types

• Schema migration

  DTS migrates the schemas of objects from the source database to the destination database. DTS supports schema migration for the following types of objects: table, view, trigger, stored procedure, and stored 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 stored functions.
  • DTS does not migrate user information. To call a view, stored procedure, or stored function of the destination database, you must grant the read and write permissions to INVOKER.
• Full data migration
  DTS migrates the existing data of objects from the Amazon RDS for MySQL instance to 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 size of used tablespace of the destination database is larger than that of the source database.
  • During schema migration and full data migration, do not perform DDL operations in the source database. For example, do not add a field. Otherwise, data migration may fail.
• Incremental data migration

  After full data migration is complete, DTS retrieves binary log files from the Amazon RDS for MySQL instance. Then, DTS synchronizes incremental data from the Amazon RDS for MySQL instance to the ApsaraDB RDS for MySQL instance. Incremental data migration allows you to ensure service continuity when you migrate data between MySQL databases.

Permissions required for database accounts

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

• Amazon RDS for MySQL instance: Create an account for a self-managed MySQL database and configure binary logging
• ApsaraDB RDS for MySQL instance: Create an account on an ApsaraDB RDS for MySQL instance and Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance.

Before you begin

1. Log on to the Amazon RDS Management Console.
2. Go to the Basic Information page of the Amazon RDS for MySQL instance.
3. In the Security group rules section, click the name of the security group to which the existing inbound rule belongs.
   
4. On the Security Groups page, click the Inbound tab in the Security Group section. On the Inbound tab, click Edit. In the Edit inbound rules dialog box, add the CIDR blocks of DTS servers that reside in the corresponding region to the inbound rule. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
   

   Note

   • You need to add only the CIDR blocks of DTS servers that reside in the same region as the destination database. For example, the source database resides in the Singapore region and the destination database resides in the China (Hangzhou) region. You need to add only the CIDR blocks of DTS servers that reside in the China (Hangzhou) region.
   • You can add all of the required CIDR blocks to the inbound rule at a time.
5. Log on to the Amazon RDS for MySQL database and specify the number of hours to retain binary log files. Skip this step if you do not need to perform incremental data migration.

   call mysql.rds_set_configuration('binlog retention hours', 24);

   Note

   • The preceding statement sets the retention period of binary log files to 24 hours. The maximum retention period is 168 hours, which equals seven days.
   • The binary logging feature of the Amazon RDS for MySQL instance must be enabled, and the value of the binlog_format parameter must be set to row. If the MySQL version is 5.6 or later, the value of the binlog_row_image parameter must be set to full.

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 lower-right corner 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 name of the task. DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. You do not need to specify a unique task name.
   Source Database	Instance Type	The instance type of the source database. Select User-Created Database with Public IP Address.
   	Instance Region	The region in which the source database resides. If you select User-Created Database with Public IP Address as the instance type of the source database, you do not need to specify the Instance Region parameter.
   	Database Type	The type of the source database. Select MySQL.
   	Hostname or IP Address	The endpoint that is used to access the Amazon RDS for MySQL instance. Note You can obtain the endpoint on the Basic Information page of the Amazon RDS for MySQL instance.
   	Port Number	The service port number of the Amazon RDS for MySQL instance. Default value: 3306.
   	Database Account	The database account of the Amazon RDS for MySQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	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 is displayed. If the Failed message is displayed, click Check next to Failed to modify the source database parameters based on the check results.
   Destination Database	Instance Type	The instance type of the destination database. Select RDS Instance.
   	Instance Region	The region in which the ApsaraDB RDS for MySQL instance resides.
   	RDS Instance ID	The ID of the ApsaraDB RDS for MySQL instance.
   	Database Account	The database account of the ApsaraDB RDS for MySQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	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 specified parameters are valid. If the specified parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed to modify the destination database parameters based on the check results.
   	Encryption	Specifies whether to encrypt the connection to the destination instance. Select Non-encrypted or SSL-encrypted based on your business requirements. If you 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 displayed 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.

   If the source or destination database instance is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, or is a self-managed database hosted on Elastic Compute Service (ECS), DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database. For more information about the CIDR blocks of DTS servers, see the "CIDR blocks of DTS servers" section of the Add the CIDR blocks of DTS servers to the security settings of on-premises databases topic.

   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 the migration types and the objects to be migrated.
   

   Parameter or setting	Description
   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. Note If Incremental Data Migration is not selected, do not write data to the source database during data migration. This ensures data consistency between the source and destination databases. During schema migration and full data migration, do not perform DDL operations on the objects to be migrated. Otherwise, the objects may fail to be migrated.
   Rename Databases and Tables	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.
   Retry Time for Failed Connection	By default, if DTS fails to connect to the source or destination database, DTS retries within the next 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 If DTS retries a connection, you are charged for the operation of the DTS instance. We recommend that you specify the retry time range based on your business requirements and release the DTS instance at the 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 tables	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. 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, latency may occur for the data migration task. 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 ApsaraDB RDS for MySQL instance 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.
    • 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 may be incomplete. You can wait until the data migration task automatically stops.

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

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

      Important 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 latency 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.
12. Switch your workloads to the ApsaraDB RDS for MySQL instance.