Migrate a self-managed MariaDB database to an Alibaba Cloud RDS database - Data Transmission Service

This topic describes how to use Data Transmission Service (DTS) to migrate data from a self-managed MariaDB database to an RDS for MariaDB instance. DTS supports schema migration, full data migration, and incremental data migration. You can use these three migration types in combination to migrate your self-managed MariaDB database to the cloud without service interruptions.

Note

To migrate data from a self-managed MariaDB database to an RDS for MySQL instance, you can follow the instructions in this topic and replace the destination instance information with that of an RDS for MySQL instance.

Prerequisites

You have created a destination RDS for MariaDB instance.
The storage space of the destination RDS for MariaDB instance must be larger than that of the source self-managed MariaDB database.

Precautions

Note

During schema migration, DTS migrates foreign keys from the source database to the destination database.
During full and incremental data migration, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. Data inconsistency may occur if cascade update or delete operations are performed on the source database while the task is running.

Type	Description
Source database limits	Bandwidth requirements: The server that hosts the source database must have sufficient outbound bandwidth. Otherwise, the data migration speed is affected. The tables to be migrated must have primary keys or unique constraints, and the fields must be unique. Otherwise, duplicate data may appear in the destination database. If you migrate objects at the table level and need to edit them, such as mapping table or column names, and the number of tables in a single migration task exceeds 1,000, we recommend that you configure multiple migration instances for different batches of tables. You can also configure a migration instance for the entire database. If you perform incremental migration, note the following for data logs: You must enable binary logging (binlog) and set binlog_row_image to full. Otherwise, an error is reported during the precheck and the data migration task cannot start. DTS requires that the data logs of the source database are retained for at least seven days. Otherwise, DTS may fail to obtain the data logs, which causes the task to fail. In extreme cases, data inconsistency or data loss may occur. Issues caused by a data log retention period that is shorter than the required period are not covered by the DTS Service-Level Agreement (SLA). During the full migration phase, do not perform DDL operations that change the database or table schemas. Otherwise, the data migration task fails. Note During the full migration phase, DTS queries the source database. This creates metadata locks, which may block DDL operations from running on the source database. If you perform only full data migration, do not write new data to the source database. Otherwise, data inconsistency between the source and destination databases occurs. To maintain real-time data consistency, we recommend that you select both full data migration and incremental data migration.
Other limits	Make sure that no invisible columns exist in the data to be migrated from the source database or in the columns that receive data in the destination database. Otherwise, the DTS instance may fail to run or data loss may occur. During a full data migration task, DTS consumes some read and write resources of the source and destination databases. This may increase the database load. We recommend that you evaluate the performance of the source and destination databases before you run the migration instance. Run the instance during off-peak hours. For example, run the instance when the CPU load of the source and destination databases is below 30%. Full data migration runs concurrent INSERT operations, which causes table fragmentation in the destination database. After full data migration is complete, the table storage space in the destination database is larger than that in the source database. During DTS migration, if data is written to the destination database from sources other than DTS, data inconsistency between the source and destination databases may occur. This can even cause the migration instance to fail. After the DTS migration is complete, you can use Data Management (DMS) to perform online DDL operations. If a DDL statement fails to be written to the destination database, the DTS task continues to run. You need to view the failed DDL statement in the task logs. If an instance fails, DTS helpdesk will try to recover the instance within 8 hours. During the recovery process, operations such as restarting the instance and adjusting parameters may be performed. Note When parameters are adjusted, only the parameters of the DTS instance are modified. The parameters of the database are not modified. The parameters that may be modified include but are not limited to those described in Modify instance parameters.
Special cases	Because the source MariaDB database is a self-managed database, note the following: If a primary/secondary switchover occurs in the source database during migration, the migration task fails. DTS calculates the latency by comparing the timestamp of the last piece of data migrated to the destination database with the current timestamp. If no DML operations are performed on the source database for a long time, the latency information may be inaccurate. If the task shows a high latency, you can run a DML operation on the source database to update the latency information.

Billing

Migration type	Link configuration fee	Data transfer cost
Schema migration and full data migration	Free of charge.	This is free of charge in this scenario.
Incremental data migration	Charged. For more information, see Billing overview.	This is free of charge in this scenario.

Migration types

Schema migration
Data Transmission Service (DTS) migrates the schemas of the selected objects from the source database to the destination database.
Note
- DTS supports schema migration for the following types of objects: tables, views, triggers, stored procedures, and stored functions.
  Note
  The routine_body of the stored procedure, routine_body of the stored functions, and select_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.
  Note
  The 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	ALTER TABLE and ALTER VIEW CREATE FUNCTION, CREATE INDEX, CREATE PROCEDURE, CREATE TABLE, and CREATE VIEW DROP INDEX and DROP TABLE RENAME TABLE Important RENAME TABLE operations may cause data inconsistency between the source and destination databases. For example, if you select a table as the object to be migrated and rename the table during data migration, the data of this table is not migrated to the destination database. To prevent this situation, you can select the database to which this table belongs as the object to be migrated when you configure the data migration task. Make sure that the databases to which the table belongs before and after the RENAME TABLE operation are added to the objects to be migrated. TRUNCATE TABLE

Permissions required for database accounts

Database

Schema migration

Full data migration

Incremental data migration

Self-managed MariaDB database

SELECT permission

For incremental data migration: SELECT permission on the objects to be migrated.

REPLICATION CLIENT, REPLICATION SLAVE, and SHOW VIEW permissions.

Permissions to create databases and tables. This allows DTS to create a database named test to record heartbeat data during migration.

RDS for MariaDB instance

Read and write permissions

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

For self-managed MariaDB instances, see Create an account and Grant permissions to an account.
For an RDS for MariaDB instance, see Create an account and Modify or reset the permissions of an account.

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
1. Log on to the DTS console.
2. In the left-side navigation pane, click Data Migration.
3. In the upper-left corner of the page, select the region in which the data migration instance resides.
DMS console
Note
The 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.
1. Log on to the DMS console.
2. In the top navigation bar, move the pointer over Data + AI > DTS (DTS) > Data Migration.
3. 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.
Note
- Skip 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.

Warning

After 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	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	Select MariaDB.
	Access Method	Select an option based on the deployment location of the source database. This topic uses Self-managed Database On ECS as an example to describe the configuration flow.
	Instance Region	Select the region where the source MariaDB database is located.
	ECS Instance ID	Select the ID of the ECS instance.
	Port	The service port of the source MariaDB database. The port must be accessible over the Internet. Default value: 3306.
	Database Account	Enter the account for the source MariaDB database. For information about the required permissions, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.
	Encryption	Select Non-encrypted Connection.
Destination Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	Select Mariadb.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	Select the region where the destination RDS for MariaDB instance is located.
	RDS Instance ID	Select the ID of the destination RDS for MariaDB instance.
	Database Account	Enter the database account of the destination RDS instance. For information about the required permissions, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.
	Encryption	You can select Unencrypted Connection.

In the lower part of the page, click Test Connectivity and Proceed.
Note
- Make sure that the CIDR blocks of DTS servers can be automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add DTS server IP addresses to a whitelist.
- If the source or destination database is a self-managed database and its Access Method is not set to Alibaba Cloud Instance, click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

Configure the objects to be migrated.

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. Note If 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 method to migrate triggers as needed. If no triggers are to be migrated, you do not need to configure this parameter. For more information, see Configure a method to synchronize or migrate triggers. Note This option is available only if you select both Schema Migration and Incremental Data Migration for Migration Types.
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. Note If 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. Warning If 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.
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. Note You 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. Note If you use the object name mapping feature, other objects that depend on the renamed object may fail to be migrated. To filter data using a WHERE condition, right-click the table that you want to migrate in the Selected Objects box and configure the WHERE condition in the dialog box that appears. For more information, see Filter the data to be migrated. To select the SQL operations to migrate at the database or table level, right-click the object that you want to migrate in the Selected Objects box and select the SQL operations to migrate in the dialog box that appears.

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.
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. Note If 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. Important The 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. Note You 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. Note You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
Environment Tag	You can select an environment tag to identify the instance as needed. This parameter is optional.
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.

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.
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, 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 the 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?
New Instance Class	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. In the message that appears, click OK.
You can view the progress of the task on the Data Migration page.
Note
- If a data migration task cannot be used to migrate incremental data, the task automatically stops. The Completed is displayed in the Status section.
- If a data migration task can be used to migrate incremental data, the task does not automatically stop. The incremental data migration task never stops or completes. The Running is displayed in the Status section.