This topic describes how to migrate data from a self-managed MySQL database to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. When you migrate data from a self-managed MySQL database to Alibaba Cloud, you can select all the supported migration types to ensure service continuity.
Before you use DTS, make sure that DTS has the permissions to access Alibaba Cloud resources. For more information, see Authorize DTS to access Alibaba Cloud resources.
Supported source and destination databases
You can use DTS to migrate data between the following types of MySQL databases. In this example, the source database is a self-managed MySQL database with a public IP address and the destination database is hosted in an ApsaraDB RDS for MySQL instance. You can follow the procedure to configure data migration tasks for other types of MySQL databases.
Source database | Destination database |
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Prerequisites
The engine version of the self-managed MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.
The CIDR blocks of DTS servers are added to the IP address whitelist of the source MySQL database if the database is an on-premises database. This setting ensures that DTS servers can access the source MySQL database. For more information, see Add the CIDR blocks of DTS servers.
The destination ApsaraDB RDS for MySQL instance is created. For more information, see Create an ApsaraDB RDS for MySQL instance.
The available storage space of the ApsaraDB RDS for MySQL instance is larger than the total size of the data in the self-managed MySQL database.
Limits
During schema migration, DTS migrates foreign keys from the source database to the destination database.
During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If you perform the cascade and delete operations on the source database during data migration, data inconsistency may occur.
Category | Description |
Limits on the source database |
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Other limits |
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Special cases |
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Billing
Migration type | Instance configuration fee | Internet traffic fee |
Schema migration and full data migration | Free of charge. | Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview. |
Incremental data migration | Charged. For more information, see Billing overview. |
Migration types
Schema migration
Data Transmission Service (DTS) migrates the schemas of the selected objects from the source database to the destination database.
NoteDTS supports schema migration for the following types of objects: tables, views, triggers, stored procedures, and stored functions.
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 historical data of the selected objects from the source database to the destination database.
Incremental data migration
After full data migration is completed, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.
SQL operations that can be performed for incremental data migration
Operation type | SQL statement |
DML | INSERT, UPDATE, and DELETE |
DDL |
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Permissions required for database accounts
Database | Schema migration | Full data migration | Incremental data migration |
Self-managed MySQL database | SELECT permission | SELECT permission | SELECT permission on the objects to be migrated REPLICATION CLIENT, REPLICATION SLAVE, and SHOW VIEW permissions Permissions to create databases and tables. The permissions allow DTS to create a database named dts to record heartbeat data during migration. |
ApsaraDB RDS for MySQL instance | Read and write permissions |
For more information about how to create a database account and grant permissions to the database account, see the following topic:
Self-managed MySQL database: Create an account for a self-managed MySQL database and configure binary logging
ApsaraDB RDS for MySQL instance: Create an account and Modify the permissions of an account
Procedure
Go to the Data Migration page.
Log on to the Data Management (DMS) console.
In the top navigation bar, move the pointer over DTS.
Choose .
NoteThe actual operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.
You can also go to the Data Migration page of the new DTS console.
From the drop-down list on the right side of Data Migration Tasks, select the region in which your data migration instance resides.
NoteIf you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.
Click Create Task. In the Create Task wizard, configure the source and destination databases. The following table describes the parameters.
WarningAfter you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.
Section
Parameter
Description
None
Task Name
The name of the task. DTS automatically assigns a name to the task. 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
Select a DMS database instance
The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements.
If you select an existing instance, DTS automatically populates the parameters for the database.
If you do not select an existing instance, you must configure parameters for the source database.
Database Type
The type of the source database. Select MySQL.
Access Method
The access method of the source database. Select an access method based on the deployment location of the source database. In this example, Public IP Address is selected.
NoteIf you select other access methods, you must set up the environment that is required for the self-managed database. For more information, see Preparation overview.
Instance Region
The region in which the source MySQL database resides.
Hostname or IP address
The endpoint that is used to access the source MySQL database. In this example, the public IP address is entered.
Port Number
The service port number of the source MySQL database. The port must be accessible over the Internet. Default value: 3306.
Database Account
The account of the source MySQL database. 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.
Destination Database
Select a DMS database instance
The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements.
If you select an existing instance, DTS automatically populates the parameters for the instance.
If you do not select an existing instance, you must configure parameters for the destination database.
Database Type
The type of the destination database. Select MySQL.
Access Method
The access method of the destination instance. In this example, select Alibaba Cloud Instance.
Instance Region
The region in which 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 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.
Encryption
Specifies whether to encrypt the connection to the source database 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 the SSL encryption feature.
In the lower part of the page, click Test Connectivity and Proceed.
If an IP address whitelist is configured for your self-managed database, add the CIDR blocks of DTS servers to the IP address whitelist. Then, click Test Connectivity and Proceed.
WarningIf the public CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database instance or to the security group rules of an ECS instance, 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: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or security group rules and forbidding unauthorized CIDR blocks, or connecting the database instance to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
Configure the objects to be migrated and advanced settings.
Parameter
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.
NoteIf you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
Processing Mode of Conflicting Tables
Precheck and Report Errors: checks whether the destination database contains tables that use the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started.
NoteIf the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. For more information, see Map object names.
Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases.
WarningIf you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to the following potential risks:
If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database.
If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
Capitalization of Object Names in Destination Instance
The capitalization of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Source Objects
Select one or more objects from the Source Objects section. Click the icon and add the objects to the Selected Objects section.
NoteYou can select columns, tables, or schemas as the objects to be migrated. If you select tables or columns as the objects to be migrated, DTS does not migrate other objects, such as views, triggers, or stored procedures, to the destination database.
Selected Objects
- To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
- To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
NoteIf you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Set filter conditions.
To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate. For more information about the SQL operations that can be migrated, see SQL operations that can be performed for incremental data migration.
Click Next: Advanced Settings to configure advanced settings.
Parameter
Description
Monitoring and Alerting
Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values:
No: does not configure alerting.
Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see Configure monitoring and alerting when you create a DTS task.
Copy the temporary table of the Online DDL tool that is generated in the source table to the destination database
If you use DMS or the gh-ost tool to perform online DDL operations on the source database, you can specify whether to migrate the data of temporary tables generated by online DDL operations. Valid values:
ImportantYou cannot use tools such as pt-online-schema-change to perform online DDL operations on the source database. Otherwise, the DTS task fails.
Yes: DTS migrates the data of temporary tables generated by online DDL operations.
NoteIf online DDL operations generate a large amount of data, latency may occur for the data migration task.
No, Adapt to DMS Online DDL: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using DMS are migrated.
NoteIf you select No, Adapt to DMS Online DDL, the tables in the destination database may be locked.
No, Adapt to gh-ost: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using the gh-ost tool are migrated. You can use the default or custom regular expressions to filter out the shadow tables of the gh-ost tool and tables that are not required.
NoteIf you select No, Adapt to gh-ost, the tables in the destination database may be locked.
Retry Time for Failed Connections
The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. 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 you set different retry time ranges for multiple data migration tasks that have the same source or destination database, the shortest retry time range that is set takes precedence.
- When DTS retries a connection, 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 your earliest opportunity after the source and destination instances are released.
Configure ETL
Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values:
Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task.
No: does not configure the ETL feature.
Whether to delete SQL operations on heartbeat tables of forward and reverse tasks
Specifies whether to write SQL operations on heartbeat tables to the source database while the DTS instance is running.
Yes: does not write SQL operations on heartbeat tables. In this case, a latency of the DTS instance may be displayed.
No: writes SQL operations on heartbeat tables. In this case, specific features such as physical backup and cloning of the source database may be affected.
In the lower part of the page, click Next: Save Task Settings and Precheck.
You can move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters to view the parameters to be specified when you call the relevant API operation to configure the DTS task.
NoteBefore 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, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.
If an alert is generated for an item during the precheck, perform the following operations based on the scenario:
If the alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.
If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.
Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.
On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.
Section
Parameter
Description
New Instance Class
Resource Group Settings
The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
Instance Class
DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Instance classes of data migration instances.
Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.
Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.
FAQ
What do I do if the "JDBC: [conn_error, cause: null, message from server: "Host 'XXX' is not allowed to connect to this MySQL server"]; PING: []; TELNET: []; requestId=[XXX]" error message is displayed during a connectivity test?
The error message indicates that a Java Database Connectivity (JDBC) exception occurs. In this case, you must check the username, password, and permissions of the account for JDBC. Alternatively, you can use a privileged account to test connectivity.