Migrate data from an Amazon RDS for MySQL database to an ApsaraDB RDS for MySQL database

Precautions

• DTS uses read and write resources of the source and destination databases during full data migration. This may increase the database load. 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 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 usage of the source and destination databases is less than 30%.
• The source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, duplicate data may exist in the destination database.
• DTS uses the ROUND(COLUMN,PRECISION) function to retrieve values from columns of the float or double data type. If the precision is not specified, 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 how to create a database and the database naming conventions, see Create databases and accounts.
• DTS automatically resumes a failed data migration task. Before you switch your workloads to the destination database, stop or release the data migration task. Otherwise, the data in the source database will overwrite the data in the destination database 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 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. Before a user can call views, stored procedures, and functions of the destination database, you must grant the read/write permissions to the user.
• Full data migration
  DTS migrates historical data of the required objects from the source Amazon RDS for MySQL database to the destination ApsaraDB RDS for MySQL database.

  Note

  • During full data migration, concurrent INSERT operations cause segments in the tables of the destination instance. After full data migration is complete, the tablespace of the destination instance is larger than that of the source instance.
  • To ensure data consistency, do not write new data into the Amazon RDS for MySQL instance during full data migration.
• Incremental data migration

  After full data migration is complete, DTS retrieves binary log files from the source Amazon RDS for MySQL database. Then, DTS synchronizes incremental data from the source Amazon RDS for MySQL database to the destination ApsaraDB RDS for MySQL database. Incremental data migration helps you 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:

• Create an account for a user-created MySQL database and configure binary logging for an Amazon RDS for MySQL database
• Create an account for an RDS for MySQL instance and Change the permissions of an account for an RDS for MySQL instance for an ApsaraDB RDS for MySQL database

Preparations before data migration

1. Log on to the Amazon RDS Management Console.
2. Go to the Basic information page of the source 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 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 only need to add the CIDR blocks of DTS servers that are located in the same region as the destination database. For example, the source database is located in Singapore and the destination database is located in Hangzhou. You only need to add the CIDR blocks of DTS servers that are located in the China (Hangzhou) region.
   • You can add all the required CIDR blocks to the inbound rule at one 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 command sets the retention period of binary log files to 24 hours. The maximum value is 168 hours (7 days).
   • The binary logging feature of Amazon RDS for MySQL must be enabled and the value of the binlog_format parameter must be set to row. If the version of MySQL 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 Migration Tasks the 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 information about the source and destination databases for the data migration task.
   

   Section	Parameter	Description
   N/A	Task Name	DTS automatically generates a task name. We recommend that you use an informative name for easy identification. You do not need to use a unique task name.
   Source Database	Instance Type	Select User-Created Database with Public IP Address.
   	Instance Region	If the instance type is set to User-Created Database with Public IP Address, you do not need to specify the instance region.
   	Database Type	Select MySQL.
   	Hostname or IP Address	Enter the endpoint that is used to connect to the Amazon RDS for MySQL database. Note You can obtain the endpoint on the Basic information page of the source Amazon RDS for MySQL instance.
   	Port Number	Enter the service port number of the Amazon RDS for MySQL database. The default port number is 3306.
   	Database Account	Enter the account for the Amazon RDS for MySQL database. For more information about permissions required for the account, see Permissions required for database accounts.
   	Database Password	Enter the password for the database account. Note After the source database information is specified, click Test Connectivity next to Database Password to verify whether the specified information is valid. If the specified information is valid, the Passed message appears. If the Failed message appears, click Check in the Failed message. Modify the source database information as prompted.
   Destination Database	Instance Type	Select RDS Instance.
   	Instance Region	Select the region where the ApsaraDB RDS for MySQL instance resides.
   	RDS Instance ID	Select the ID of the ApsaraDB RDS for MySQL instance.
   	Database Account	Enter the database account of the ApsaraDB RDS for MySQL instance. For more information about permissions required for the account, see Permissions required for database accounts.
   	Database Password	Enter the password for the database account. Note After the destination database information is specified, click Test Connectivity next to Database Password to verify whether the specified information is valid. If the specified information is valid, the Passed message appears. If the Failed message appears, click Check in the Failed message. Modify the destination database information as prompted.
   	Encryption	Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the RDS instance before configuring the data migration task. For more information, see Configure SSL encryption for an RDS for MySQL instance. Note The Encryption parameter is available only in mainland China and Hong Kong(China).

6. In the lower-right corner of the page, click Set Whitelist and Next.
   Note The CIDR blocks of DTS servers are automatically added to the whitelist of the ApsaraDB for RDS instance. This ensures that DTS servers can connect to the ApsaraDB for RDS instance.
7. Select the migration types and objects to be migrated.
   

   Parameter	Description
   Migration types	To perform only full data migration, select Schema Migration and Full Data Migration. To migrate data with minimal downtime, you must select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If Incremental Data Migration is not selected, do not write data into 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.
   Objects to be migrated	In the Available section, select the objects to be migrated and click the icon to add the objects to the Selected section. Note You can select databases, tables, or columns as the objects to be migrated. After an object is migrated to the destination instance, the name of the object remains unchanged. If you want an object to have a different name after the object is migrated to the ApsaraDB RDS for MySQL instance, you can use the object name mapping feature provided by DTS. For more information about how to use this feature, see Object name mapping. If you use the object name mapping feature on an object, other objects that are dependent on the object may fail to be migrated.

8. Click Precheck on the lower right of the page.
   Note

   • A precheck is performed for a data migration task. A data migration task can be started only if it passes the precheck.
   • If the precheck fails, click corresponding to each failed item to view the details. Fix the problems as instructed and run the precheck again.
9. After the precheck is passed, click Next.
10. On the Confirm Settings dialog box that appears, specify Channel Specification and select the 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

      Do not manually stop a migration task. Otherwise, data migrated to the destination database will be incomplete. Wait until the data migration task stops when it is complete.

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

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

      Note Select an appropriate time point to manually end the migration task. For example, you can end the migration task during off-peak hours or before you switch your workloads to the destination cluster.
      1. When the task progress bar switches to Incremental Data Migration and the message The migration task is not delayed appears, stop writing new data to the source database for a few minutes. Then, the progress bar will show the latency of the incremental data migration.
      2. When the status of incremental data migration changes to The migration task is not delayed, manually stop the migration task.
12. Switch your workloads to the ApsaraDB RDS for MySQL instance.