Data Transmission Service:Migrate data from an Amazon RDS for MySQL 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.
• 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 instance will overwrite the data in the destination instance after the task is resumed.

Billing

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 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 read and write permissions to INVOKER.
• Full data migration
  DTS migrates historical data of the required 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 instance. After full data migration is complete, the size of used tablespace of the destination instance is larger than that of the source instance.
  • 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 and authorize a database account, see the following topics:

• Amazon RDS for MySQL instances: Create an account for a user-created MySQL database and configure binary logging
• ApsaraDB RDS for MySQL instances: 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

Preparations

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 corresponding to the existing inbound rule.
   
4. On the Security Groups page, click the Inbound tab in the Security Group section. On the Inbound tab, click Edit to add the CIDR blocks of DTS servers 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 the CIDR blocks of DTS servers that only reside in the same region as the destination database. For example, the source database resides in the Singapore (Singapore) region and the destination database resides in the China (Hangzhou) region. You need to add the CIDR blocks of DTS servers that only 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 value is 168 hours (7 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.
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 User-Created Database with Public IP Address.
   	Instance Region	If you select User-Created Database with Public IP Address as the access method of the source database, you do not need to specify the Instance Region parameter.
   	Database Type	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. Modify the source database parameters based on the check results.
   Destination Database	Instance Type	Select RDS Instance.
   	Instance Region	The region where 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. 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 instance before you configure the data synchronization task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance. Note The Encryption parameter is available only within 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 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. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. 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.
   • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database instance or 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 account 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.
   • After the DTS task is completed or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
7. Select the migration types and the objects to be migrated.
   

   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. Note 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. 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.
   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 range for failed connections to the source and destination databases	By default, if DTS fails to connect to the source and destination databases, DTS retries within the following 12 hours. You can specify the retry time range based on your business requirements. If DTS is reconnected 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 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, latency may occur for the 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, 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 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 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.
12. Switch your workloads to the ApsaraDB RDS for MySQL instance.