Migrate data from Amazon RDS for SQL Server to Alibaba Cloud - ApsaraDB RDS

This topic describes how to migrate data from an Amazon RDS for SQL Server instance to an ApsaraDB RDS for SQL Server instance by using Data Transmission Service (DTS).

Background information

You can use one of the following methods to migrate data from an Amazon RDS for SQL Server instance to an ApsaraDB RDS for SQL Server instance.

Use the ApsaraDB RDS console.
You can use the ApsaraDB RDS console to migrate data from an Amazon RDS for SQL Server instance to an ApsaraDB RDS for SQL Server instance in a convenient and efficient manner.
Note
By default, schema migration, full data migration, and incremental data migration are performed.
Use the DTS console.
You can use the DTS console to configure a data migration task. In this case, you can select the migration types, such as schema migration, full data migration, and incremental data migration, and configure advanced settings based on your business requirements.

Prerequisites

The source Amazon RDS for SQL Server instance is connected to Alibaba Cloud and can be accessed by DTS. For more information, see Connect an AWS database to Alibaba Cloud.
The destination ApsaraDB RDS for SQL Server instance is created. The available storage space of this instance is larger than the total size of data in the source instance. For more information, see Create an ApsaraDB RDS for SQL Server instance.

Usage notes

Note

DTS does not migrate foreign keys in the source database to the destination database. Therefore, the cascade and delete operations of the source database are not migrated to the destination database.

Category	Description
Limits on the source database	The source database version must meet the following requirements: If the source database runs SQL Server Enterprise Edition, its version must be SQL Server 2008 or later. If the source database runs SQL Server Standard Edition, its version must be SQL Server 2016 SP1 or later. If the source database runs SQL Server Enterprise Edition or SQL Server Standard Edition and its version is SQL Server 2017, we recommend that you update the version. The server on which the source database is deployed must have sufficient outbound bandwidth. Otherwise, the data migration speed decreases. The tables to be migrated must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records. You can run a single data migration task to migrate up to 10 databases. If you want to migrate more than 10 databases, we recommend that you configure multiple tasks to migrate the databases. Otherwise, the performance and stability of your data migration task may be compromised. If you perform only incremental data migration, the data logs of the source database must be stored for more than 24 hours. If you perform both full data migration and incremental data migration, the data logs of the source database must be stored for at least seven days. Otherwise, DTS may fail to obtain the data logs and the task may fail. In exceptional circumstances, data inconsistency or data loss may occur. After full data migration is complete, you can set the retention period to more than 24 hours. Make sure that you set the retention period of data logs based on the preceding requirements. Otherwise, the service reliability or performance stated in Service Level Agreement (SLA) of DTS cannot be guaranteed. Limits on operations to be performed on the source database: During schema migration and full data migration, do not execute DDL statements to change the schemas of databases or tables. Otherwise, the data migration task fails. If you perform only full data migration, do not write data to the source database during data migration. Otherwise, data will be inconsistent between the source and destination databases. To ensure data consistency, we recommend that you select schema migration, full data migration, and incremental data migration as the migration types. You cannot use a read-only instance as the source database.
Other limits	DTS does not migrate data of the following types: TEXT, CURSOR, ROWVERSION, SQL_VARIANT, HIERACHYID, and GEOMETRY. DTS migrates incremental data by querying change data capture (CDC) instances. Take note of the following limits if you want to perform incremental data migration: DTS obtains incremental data by querying the CDC instance of each table in the source database. Therefore, the number of tables to be migrated from the source database cannot exceed 1,000. Otherwise, the data migration task may be delayed or unstable. You cannot execute a DDL statement to add or remove columns more than twice in a minute. Otherwise, the data migration task may fail. During data migration, you cannot modify the CDC instances of the source database. Otherwise, the data migration task may fail or data loss may occur. If you configure a task to migrate multiple tables in multiple databases, stability and performance issues may occur. Incremental data migration has a latency of about 10 seconds. If you want to migrate data between different versions of databases, make sure that the database versions are compatible. If the data migration task involves incremental data migration, you cannot perform the reindexing operation and must disable the triggers and foreign keys in the destination database. Otherwise, the data migration task may fail and data loss may occur. Note DTS cannot migrate DDL operations related to the primary key of a table for which CDC is enabled. If the number of CDC-enabled tables to be migrated in a single data migration task exceeds 1,000, the precheck fails. DTS automatically creates a destination database in the ApsaraDB RDS for SQL Server instance. However, if the name of the database to be migrated does not conform to the naming convention of ApsaraDB RDS for SQL Server instances, you must manually create a database in the destination ApsaraDB RDS for SQL Server instance before you configure the data migration task. For more information, see Create a database. In Incremental Synchronization Based on Logs of Source Database mode, DTS creates a trigger named dts_cdc_sync_ddl, a heartbeat table named dts_sync_progress, and a DDL history table named dts_cdc_ddl_history in the source database to ensure that the latency of data migration is accurate. In hybrid log-based parsing incremental synchronization mode, DTS creates a trigger named dts_cdc_sync_ddl, a heartbeat table named dts_sync_progress, and a DDL history table named dts_cdc_ddl_history and enables CDC for the source database and specific tables. We recommend that you set the maximum number of records per second to 1,000 for the tables for which CDC is enabled in the source database. Before you migrate data, evaluate the impact of data migration on the performance of the source database and destination cluster. We recommend that you migrate data during off-peak hours. 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. During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the tablespace of the destination database is larger than that of the source database. You must make sure that the precision settings for columns of the FLOAT or DOUBLE data type meet your business requirements. 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. DTS attempts to resume data migration tasks that failed within the last seven days. Before you switch workloads to the destination cluster, you must stop or release the failed tasks. You can also execute the `REVOKE` statement to revoke the write permissions from the accounts that are used by DTS to access the destination database. Otherwise, the data in the source database overwrites the data in the destination database after the data migration task is resumed.

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.

SQL operations that can be incrementally migrated

Operation type	SQL statement
DML	INSERT, UPDATE, and DELETE Note If an UPDATE operation updates only the large fields, DTS does not migrate the operation.
DDL	CREATE TABLE Note If a CREATE TABLE operation creates a partitioned table or a table that contains functions, DTS does not migrate the operation. ALTER TABLE ADD COLUMN and DROP COLUMN DROP TABLE CREATE INDEX and DROP INDEX Note DTS does not migrate transactional DDL operations. DTS does not migrate DDL operations that contain user-defined types. If the source database uses the mixed log-based parsing mode, all common DDL operations can be migrated.

Permissions required for database accounts

Database type	Schema migration	Full data migration	Incremental data migration	References
Amazon RDS for SQL Server	The SELECT permission	The SELECT permission	Permissions of the sysadmin role Note A privileged account of an Amazon RDS for SQL Server instance has the required permissions. CDC can be enabled for stored procedures at the database level.	For more information, contact Amazon Web Services (AWS).
ApsaraDB RDS for SQL Server instance	Read and write permissions			Create a privileged account or a standard account and Modify the permissions of an account

Procedure

Use the ApsaraDB RDS console

Go to the Data Migration tab of the destination ApsaraDB RDS for SQL Server instance.
1. Go to the Instances page in the ApsaraDB RDS console.
2. In the upper part of the page, select the region in which the destination ApsaraDB RDS for SQL Server instance resides.
3. Click the ID of the destination ApsaraDB RDS for SQL Server instance.
4. In the left-side navigation pane, click Data Migration and Synchronization.
5. Click the Data Migration tab.
Click One-stop Cloud.

Configure the source and destination databases. The following table describes the parameters.

Section	Parameter	Description
N/A	Task Name	The name of the DTS task. DTS automatically generates a task name. 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	Database Type	The type of the source database. Default value: SQL Server. You do not need to configure this parameter.
	Category	The type of the source SQL Server database. Select AWS.
	Access Method	The access method of the source database. Select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway based on how the source Amazon RDS for SQL Server instance is connected to Alibaba Cloud. In this example, Express Connect, VPN Gateway, or Smart Access Gateway is selected.
	Instance Region	If you set Access Method to Public IP Address, select the region in which the Amazon RDS for SQL Server instance resides. Note If the region of the Amazon RDS for SQL Server instance is not available, you can select a region that is geographically closest to the instance. If you set Access Method to Express Connect, VPN Gateway, or Smart Access Gateway, select the region of the Alibaba Cloud virtual private cloud (VPC) to which the Amazon RDS for SQL Server instance is connected.
	Connected VPC	The ID of the Alibaba Cloud VPC to which the Amazon RDS for SQL Server instance is connected. Note This parameter is available only if you set Access Method to Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	The domain name or IP address of the Amazon RDS for SQL Server instance.
	Port Number	The service port of the Amazon RDS for SQL Server instance.
	Database Account	The database account of the Amazon RDS for SQL Server instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
	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 disabled for the source database, select Non-encrypted. If SSL encryption is enabled for the source database, select SSL-encrypted. By default, DTS trusts the server certificate.
Destination Database	Database Type	The type of the destination database. Default value: SQL Server. You do not need to configure this parameter.
	Access Method	The access method of the destination database. Default value: Alibaba Cloud Instance. You do not need to configure this parameter.
	Instance Region	This parameter is set to the region in which the current ApsaraDB RDS for SQL Server instance resides. You cannot change the value of this parameter.
	Instance ID	This parameter is set to the ID of the current ApsaraDB RDS for SQL Server instance. You cannot change the value of this parameter.
	Database Account	The database account of the current ApsaraDB RDS for SQL Server instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
	Database Password	The password that is used to access the database instance.
	Encryption	Specifies whether to encrypt the connection to the destination database. Select Non-encrypted or SSL-encrypted based on your business requirements. If SSL encryption is disabled for the destination database, select Non-encrypted. If SSL encryption is enabled for the destination database, select SSL-encrypted. By default, DTS trusts the server certificate.

In the lower part of the page, click Test Connectivity and Proceed.
Make sure that the CIDR blocks of DTS servers are added to the whitelist of the Amazon RDS for SQL Server instance. Then, click Test Connectivity.
Important
If the public CIDR blocks of DTS servers are added to the whitelist of the instance, security risks may arise. 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, and regularly checking the whitelist and forbidding unauthorized CIDR blocks. For more information, see Add the CIDR blocks of DTS servers.
Select a data migration plan.
The system provides the following data migration plans based on the source database type that you select:
- Full and incremental data migration: If you select this plan, click Select Objects in the lower part of the page and proceed to the next step.
- Data migration using full and incremental backups: If you select this plan, you can skip the next step.
  Note
  You can click View Migration Documentation in the lower part of the page to view how to perform data migration by using full and incremental backups.

On the Select Objects page, configure the objects that you want to migrate. The following table describes the parameters.

Parameter	Description
Method to Migrate Triggers in Source Database	Triggers may be migrated to the destination database before incremental data migration is complete. In this case, data inconsistency occurs between the source and destination databases. You can select the method used to migrate triggers based on your business requirements. We recommend that you select Manual Migration. For more information, see Synchronize or migrate triggers from the source database. Note If you do not want to migrate triggers, you do not need to configure this parameter.
Source Objects	Select one or more objects from the Source Objects section. Click the icon to add the objects to the Selected Objects section. Note 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, and stored procedures to the destination database.
Selected Objects	To change the name of an object to be migrated in the destination instance, right-click the object in the Selected Objects section. For more information, see Map object names. To remove one or more objects that are selected for migration, click the objects in the Selected Objects section and then click the icon to move the objects to the Source Objects section. Note If 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 a table 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 the object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate.

Optional. Configure the advanced settings.

You can click Advanced Settings to view and configure the advanced settings.

Parameter	Description
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.
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.
Data Verification Mode	During full data verification, DTS uses the read resources of the source and destination databases. If you select Full Data Verification, you must also specify Maximum Number of Rows Can be Read per Second and Maximum Data Volume Can be Read per Second (Byte/s) to enable throttling for full data verification. This reduces the loads of the database servers. Note A value of 0 indicates that the full data verification speed is not limited. If you set both Maximum Number of Rows Can be Read per Second and Maximum Data Volume Can be Read per Second (Byte/s) to 0, throttling is disabled for full data verification.

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.
Wait until Success Rate becomes 100%. Then, click Next: Purchase Instance.

Purchase a data migration 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?
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 Specifications 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 dialog box that appears, click OK.
You can view the progress of the task in the task list.

Use the DTS console

Log on to the DTS console.
In the left-side navigation pane, click Data Migration.
In the top navigation bar, select the region in which the data migration instance resides.
Click Create Task to go to the task configuration page.
Optional. In the upper-right corner of the page, click New Configuration 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.

Section	Parameter	Description
N/A	Task Name	The name of the task. DTS automatically generates a task name. We recommend that you specify an informative name to identify the task. You do not need to specify a unique task name.
Source Database	Select Existing Connection	The 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 destination database. Note You can register a database with DTS on the Database Connections page or the new configuration page. For more information, see Manage database connections.
	Database Type	The type of the source database. Select SQL Server.
	Access Method	The access method of the source database. Select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway based on how the source Amazon RDS for SQL Server instance is connected to Alibaba Cloud. In this example, Express Connect, VPN Gateway, or Smart Access Gateway is selected.
	Instance Region	If you set Access Method to Public IP Address, select the region in which the Amazon RDS for SQL Server instance resides. Note If the region of the Amazon RDS for SQL Server instance is not available, you can select a region that is geographically closest to the instance. If you set Access Method to Express Connect, VPN Gateway, or Smart Access Gateway, select the region of the Alibaba Cloud virtual private cloud (VPC) to which the Amazon RDS for SQL Server instance is connected.
	Replicate Data Across Alibaba Cloud Accounts	In this example, a database instance of the current Alibaba Cloud account is used. Select No. Note This parameter is available only if you set Access Method to Express Connect, VPN Gateway, or Smart Access Gateway.
	Connected VPC	The ID of the Alibaba Cloud VPC to which the Amazon RDS for SQL Server instance is connected. Note This parameter is available only if you set Access Method to Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	The domain name or IP address of the Amazon RDS for SQL Server instance.
	Port Number	The service port of the Amazon RDS for SQL Server instance.
	Database Account	The database account of the Amazon RDS for SQL Server instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
	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 disabled for the source database, select Non-encrypted. If SSL encryption is enabled for the source database, select SSL-encrypted. By default, DTS trusts the server certificate.
Destination Database	Select Existing Connection	The 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 destination database. Note You can register a database with DTS on the Database Connections page or the new configuration page. For more information, see Manage database connections.
	Database Type	The type of the destination database. Select SQL Server.
	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
	Instance Region	The region in which the destination ApsaraDB RDS for SQL Server instance resides.
	Instance ID	The ID of the destination ApsaraDB RDS for SQL Server instance.
	Database Account	The database account of the destination ApsaraDB RDS for SQL Server instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
	Database Password	The password that is used to access the database instance.
	Encryption	Specifies whether to encrypt the connection to the destination database. Select Non-encrypted or SSL-encrypted based on your business requirements. If SSL encryption is disabled for the destination database, select Non-encrypted. If SSL encryption is enabled for the destination database, select SSL-encrypted. By default, DTS trusts the server certificate.

In the lower part of the page, click Test Connectivity and Proceed.
Make sure that the CIDR blocks of DTS servers are added to the whitelist of the Amazon RDS for SQL Server instance. Then, click Test Connectivity.
Important
If the public CIDR blocks of DTS servers are added to the whitelist of the instance, security risks may arise. 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, and regularly checking the whitelist and forbidding unauthorized CIDR blocks. For more information, see Add the CIDR blocks of DTS servers.

Configure the objects to be migrated.

On the Select Objects page, configure the objects that you want to migrate.

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. Note 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	Triggers may be migrated to the destination database before incremental data migration is complete. In this case, data inconsistency occurs between the source and destination databases. You can select the method used to migrate triggers based on your business requirements. We recommend that you select Manual Migration. For more information, see Synchronize or migrate triggers from the source database. Note You can configure this parameter only if you select both Schema Migration and Incremental Data Migration for Migration Types. If you do not want to migrate triggers, you do not need to configure this parameter.
SQL Server Incremental Synchronization Mode	Select Polling and querying CDC instances for incremental synchronization.
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 to add the objects to the Selected Objects section. Note 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, and stored procedures to the destination database.
Selected Objects	To change the name of an object to be migrated in the destination instance, right-click the object in the Selected Objects section. For more information, see Map object names. To remove one or more objects that are selected for migration, click the objects in the Selected Objects section and then click the icon to move the objects to the Source Objects section. Note If 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 a table 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 the object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate.

Click Next: Advanced Settings to configure advanced settings.

Parameter	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 1440. 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 change tracking 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	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, you do not need to configure this parameter.
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 Configure monitoring and alerting when you create a DTS task.

Click Next Step: Data Verification to configure data verification.
For more information about how to use the data verification feature, see Configure data verification.

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.
Wait until Success Rate becomes 100%. Then, click Next: Purchase Instance.

Purchase a data migration 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?
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 Specifications 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 dialog box that appears, click OK.
You can view the progress of the task in the task list.

FAQ

Can I select the objects to be verified when I configure a data migration task in the ApsaraDB RDS console?
No. By default, the objects to be verified are the same as the objects to be migrated.
What is the full data verification mode for data migration tasks configured in the ApsaraDB RDS console?
The hash values of migrated data are checked based on a sampling ratio of 100%.
What is the benchmark of full data verification for data migration tasks configured in the ApsaraDB RDS console?
Data consistency between the source and destination databases is checked by comparing all data in the source and destination databases.