Data Transmission Service (DTS) enables the migration of MySQL databases from on-premises environments, ECS instances, or other cloud platforms to an RDS MySQL instance with minimal impact on business operations. DTS offers schema migration, full migration, and incremental migration, allowing for a seamless transition of a self-managed MySQL database to the cloud without interrupting the associated application.
Prerequisites
The self-managed MySQL database is now connected to Alibaba Cloud, and the IP address range of the DTS server has been included in the database's security settings, such as security group rules, firewall, or whitelist, to permit access. For more information, see Preparations.
NoteFor a list of supported versions, see Migration Overview.
If you need to migrate incremental data, you must enable Binlog on your self-managed MySQL database. For more information, see how to create an account and configure Binlog for a self-managed MySQL database.
A target RDS MySQL instance with more storage space than that used by the self-managed MySQL database has been established. For details on instance creation, see Create an RDS MySQL instance.
Notes
During schema migration, DTS transfers foreign keys from the source database to the destination database.
During full and incremental migrations, DTS temporarily suspends constraint checks and foreign key cascade operations at the session level. Should cascade updates or deletions occur in the source database while the task is running, this may lead to data inconsistencies.
Category | Description |
Limits on the source database |
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Other limits |
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Special cases |
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Pricing
Migration type | Link configuration fee | Data transfer cost |
Schema migration and full data migration | Free of charge. | Data transfer fees are charged when data is migrated out of 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.
NoteThe
routine_body
of the stored procedure,routine_body
of the stored functions, andselect_statement
of the views cannot be modified during the migration.During schema migration, DTS changes the value of the SECURITY attribute from DEFINER to INVOKER for views, stored procedures, and functions. In addition, DTS sets the DEFINER to the destination database account used in the migration.
NoteThe SECURITY attribute and DEFINER cannot be modified during the migration.
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 required objects from the source database to the destination database.
Incremental data migration
After full data migration is complete, 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 support incremental migration
Operation type | SQL statement |
DML | INSERT, UPDATE, and DELETE |
DDL |
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Permissions required for database accounts
Database | Schema migration | Full migration | Incremental migration |
Self-managed MySQL database | SELECT permission | SELECT permission | Incremental data migration: SELECT permission on the objects to migrate REPLICATION CLIENT, REPLICATION SLAVE, SHOW VIEW The permissions to create databases and tables. The permissions allow DTS to create a database named dts to record heartbeat data during migration. |
RDS MySQL instance | Access control list |
For more information on creating and authorizing a database account, see the following topics:
If you need to migrate the account information from the source database, the database account used to set up the task must have additional permissions. For more information, see Migrate database accounts.
For self-managed MySQL databases, refer to Create an account and set binlog for self-managed MySQL.
For RDS MySQL instances, refer to Create an account and Modify account permissions.
Procedure
Use one of the following methods to go to the Data Migration page and select the region in which the data migration instance resides.
DTS console
Log on to the DTS console.
In the left-side navigation pane, click Data Migration.
In the upper-left corner of the page, select the region in which the data migration instance resides.
DMS console
NoteThe actual operation 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.
Log on to the DMS console.
In the top navigation bar, move the pointer over
.From the drop-down list to the right of Data Migration Tasks, select the region in which the data synchronization instance resides.
Click Create Task to go to the task configuration page.
Optional. Click New Configuration Page in the upper-right corner of the page.
NoteSkip this step if the Back to Previous Version button is displayed in the upper-right corner of the page.
Specific parameters in the new and previous versions of the configuration page may be different. We recommend that you use the new version of the configuration page.
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.
Category
Configuration
Description
None
Task Name
The name of the DTS task. DTS automatically generates a task name. We recommend that you specify an informative name that makes it easy to identify the task. You do not need to specify a unique task name.
Source Database
Select Existing Connection
In this example, you do not need to configure this parameter. Configure the following database information.
Database Type
Select MySQL.
Access Method
Select a connection type based on the deployment location of the source database. In this topic, Public IP is used as an example to describe the configuration process.
NoteIf a self-managed database is used as the source, you must perform the corresponding preparations. For more information, see Preparations overview.
Instance Region
Select the region where the source MySQL database resides.
Domain Name or IP
Enter the access address of the source MySQL database. In this example, enter the public address.
Port
Enter the service port of the source MySQL database (must be open to the Internet). The default value is 3306.
Database Account
Enter the account of the source MySQL database. For more information about the required permissions, see Permissions required for database accounts.
Database Password
The password that is used to access the database instance.
Encryption
Specifies whether to encrypt the connection to the source database. Select Non-encrypted or SSL-encrypted based on your business requirements.
If SSL encryption is not enabled for the self-managed MySQL database, select Non-encrypted.
If SSL encryption is enabled for the self-managed MySQL database, select SSL-encrypted. In this case, you must upload a CA Certificate and configure the CA Key parameter.
Destination Database
Select Existing Connection
In this example, you do not need to configure this parameter. Configure the following database information.
Database Type
Select MySQL.
Access Method
Select Alibaba Cloud Instance.
Instance Region
Select the region where the destination RDS MySQL instance resides.
Replicate Data Across Alibaba Cloud Accounts
In this example, the migration is performed within the same Alibaba Cloud account. Select No.
RDS Instance ID
Select the ID of the destination RDS MySQL instance.
Database Account
Enter the database account of the destination RDS MySQL instance. For more information about the required permissions, see Permissions required for database accounts.
Database Password
The password that is used to access the database instance.
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 want to set this parameter to SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the DTS task. For more information, see Use a cloud certificate to enable SSL encryption.
After completing the configuration, click Test Connectivity and Proceed at the bottom of the page. When the CIDR Blocks of DTS Servers dialog box appears, click Test Connectivity.
NoteEnsure that the DTS service's IP address range is added, either automatically or manually, to the security settings of both the source and destination databases to permit access by the DTS server. For more information, see how to add the IP address range of the DTS server.
Configure the objects to be migrated.
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On the Configure Objects page, configure the objects that you want to migrate.
Configuration
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 Schema Migration, make sure a database and a table are created in the destination database to receive data and the object name mapping feature is enabled in Selected Objects.
If 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.
Method to Migrate Triggers in Source Database
Select a migration method for triggers that suits your specific needs. If the objects to be migrated do not include triggers, configuring this parameter is unnecessary. For more information, see how to configure trigger synchronization or migration.
NoteThis parameter can be configured only if Migration Types, Schema Migration, and Incremental Data Migration are all selected.
Enable Migration Assessment
Evaluate whether the structures of the source and destination databases, such as index length, stored procedures, and dependent tables, meet the requirements. You can select Yes or No, based on your actual situation.
NoteThis parameter is configurable only when Migration Types is set to Schema Migration.
If you select Yes, the precheck duration may be extended. You can view the Assessment Result during the precheck. Note that the assessment result will not impact the outcome of the precheck.
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, and a data record has the same primary key as an existing data record in the destination database, the following scenarios may occur:
During full data migration, DTS does not migrate the data record to the destination database. The existing data record in the destination database is retained.
During incremental data migration, DTS migrates the data record to the destination database. The existing data record in the destination database is overwritten.
If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
Whether to migrate Event
Select whether to migrate events from the source database based on your actual situation. If you select Yes, you must comply with the related requirements and perform subsequent operations. For more information, see Synchronize or migrate events.
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 databases 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.
NoteUsing the object name mapping feature may cause dependent objects to fail migration.
To set WHERE conditions for data filtering, right-click the table in Selected Objects and configure the filter conditions in the resulting dialog box. For details on configuring this parameter, see Set filter conditions.
To select specific SQL operations for migration at the database or table level, right-click the relevant object in Selected Objects and choose the SQL operations in the dialog box that appears. For more information on the supported operations, see SQL operations that support incremental migration.
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Click Next: Advanced Settings to configure advanced settings.
Configuration
Description
Dedicated Cluster for Task Scheduling
By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. If you want to improve the stability of data migration tasks, purchase a dedicated cluster. For more information, see What is a DTS dedicated cluster.
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 this option, 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 this option, the tables in the destination database may be locked.
Whether to Migrate Accounts
Choose whether to migrate the account information from the source database according to your specific needs. If you select Yes, you must also choose which accounts to migrate and verify their permissions.
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 retry time range. Valid values: 10 to 1,440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
NoteIf you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later 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 the earliest opportunity after the source database and destination instance are released.
Retry Time for Other Issues
The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
ImportantThe value of the Retry Time for Other Issues parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
Enable Throttling for Full Data Migration
Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server.
NoteYou can configure this parameter only if you select Full Data Migration for the Migration Types parameter.
Enable Throttling for Incremental Data Migration
Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server.
NoteYou can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
Environment Tag
Select an environment tag to identify the instance as needed. This parameter is not required in this example.
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. Valid values:
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, features such as physical backup and cloning of the source database may be affected.
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.
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 the Configure monitoring and alerting when you create a DTS task section of the Configure monitoring and alerting topic.
Click Next Step: Data Verification to configure the data verification task.
For more information about how to use the data verification feature, see Configure a data verification task.
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Save the task settings and run a precheck.
To view the parameters to be specified when you call the relevant API operation to configure the DTS task, move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters.
If you do not need to view or have viewed the parameters, click Next: Save Task Settings and Precheck in the lower part of the page.
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 triggered for an item during the precheck:
If an 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.
Purchase an instance.
Wait until 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
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.
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Click Purchase And Start . In the OK dialog box that appears, click OK .
You can monitor the progress on the Data Migration page.
NoteIf you need to switch your business, it is recommended to perform this operation during off-peak hours to ensure the migration instance experiences no latency or low latency. For more information, see Business Switching Process .