Migrate SQL Server from AWS to Alibaba Cloud - ApsaraDB RDS

This topic describes how to use the one-stop cloud migration feature in the ApsaraDB RDS console or the data migration feature in the DTS console to migrate data from an Amazon RDS for SQL Server instance to an ApsaraDB RDS for SQL Server instance.

Prerequisites

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.
The source Amazon RDS for SQL Server instance is connected to Alibaba Cloud and can be accessed by DTS.
The source database version must meet the following requirements:
- Enterprise Edition: SQL Server 2008 or later.
- Standard Edition: SQL Server 2016 SP1 or later.
- SQL Server 2017 (including Standard Edition and Enterprise Edition): We recommend that you upgrade to a later version.

Usage notes

Pay attention to the following key points before migration. Ignoring these points may cause task failure or errors:

Database quantity limit: You can migrate up to 10 databases in a single migration task. Otherwise, stability and performance issues may occur.
Table quantity limit: For incremental migration, the number of tables to be synchronized from the source database cannot exceed 1,000. Otherwise, the task may be delayed or unstable.
Source database operation restrictions: During schema migration and full migration, do not execute DDL operations (such as modifying database or table structures). Otherwise, the task will fail.
CDC-related restrictions: If CDC is enabled for source tables and single field data exceeds 64 KB, you need to execute EXEC sp_configure 'max text repl size', -1; to adjust the configuration. Otherwise, the task may fail.
Table structure requirements: The tables to be migrated must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, duplicate data may appear in the destination database.
Foreign keys and triggers: If the migration task involves incremental data migration, you must disable the triggers and foreign keys in the destination database. Otherwise, the task may fail or data loss may occur.
Database name convention: 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 instance before configuring the migration task. Otherwise, the task may not run properly.
Data log retention period: For incremental migration tasks, the data logs of the source database must be stored for more than 24 hours. For full migration and incremental migration tasks, the data logs must be stored for at least 7 days. Otherwise, the task may fail or data inconsistency may occur.

Click to view all limits and 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. Bandwidth requirements: The server to which the source database belongs must have sufficient outbound bandwidth. Otherwise, the data migration speed is affected. 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 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. We recommend that you enable the transaction processing mode parameter of `READ_COMMITTED_SNAPSHOT` for the source database during full data migration. Otherwise, it may affect the data-write due to shared locks, data inconsistency may occur, or an instance fails to run. Issues that arise in such circumstances are not covered by the service level agreement (SLA) of DTS.
Other limits	DTS does not migrate data of the following types: TIMESTAMP, CURSOR, ROWVERSION, SQL_VARIANT, HIERARCHYID, POLYGON, GEOMETRY, and GEOGRAPHY. The pre-module of an incremental data migration task in DTS enables CDC in the source database. In this process, locked tables that lasts a few seconds occurs in the source database due to the limit of SQL Server database. 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. The CDC component can store the incremental data for 3 days by default. You can adjust the retention period by running the `exec console.sys.sp_cdc_change_job @job_type = 'cleanup', @retention= <time>;` command. Note `<time>` indicates the retention time. Unit: minutes. If the average daily number of the incremental data in the SQL Server database exceeds 10 million, we recommend setting the `<time>` parameter to 1,440. 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 or the value set in The maximum number of tables for which CDC is enabled that DTS supports. the precheck fails. If a task contains the incremental data migration, and the tables for which CDC is enabled require data whose size is larger than 64 KB in a single field, run the `exec sp_configure 'max text repl size', -1;` command in advance to configure the source database. Note By default, a CDC job can process data with the maximum size of 64 KB. 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 on 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 size of used 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 a data migration task 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. The incremental data collection modules of multiple data migration instances that share a source SQL Server database are independent of each other. If a DTS task fails to run, DTS technical support will try to restore the task within 8 hours. During the restoration, the task may be restarted, and the parameters of the task may be modified. Note Only the parameters of the task may be modified. The parameters of databases are not modified. The parameters that may be modified include but are not limited to the parameters in the "Modify instance parameters" section of the Modify the parameters of a DTS instance topic.

Billing

Migration type	Instance configuration fee	Internet traffic fee
Schema migration and full data migration	Free of charge.	When the Access Method parameter of the destination database is set to Public IP Address, you are charged for Internet traffic. For more information, see Billing overview.
Incremental data migration	Charged. For more information, see Billing overview.

Permissions required for database accounts

To ensure the successful completion of the data migration task, make sure that the database accounts of the source and destination databases have the following permissions:

Amazon RDS for SQL Server

Schema migration: The SELECT permission.
Full migration: The SELECT permission.
Incremental migration: The dbower permission (for enabling CDC).

Note

A privileged account of an Amazon RDS for SQL Server instance meets the above requirements. For further operations or confirmation, refer to AWS platform documentation or contact technical support.

ApsaraDB RDS for SQL Server instance

Schema migration, full migration, and incremental migration: Read and write permissions.

Note

You can create a privileged account or a standard account in the ApsaraDB RDS console and modify account permissions as needed.

Procedure

The one-stop cloud migration feature in the ApsaraDB RDS console migrates database schemas, full data, and incremental data by default, with simple and convenient operations. The migration feature in the DTS console supports customized migration types and more advanced parameter configurations, with relatively complex configuration.

Method 1: Use the ApsaraDB RDS console

Visit the ApsaraDB RDS instance list, select the region at the top, and then click the target instance ID.
In the left-side navigation pane, click Data Migration And Synchronization to access the Data Migration page.

Click One-stop Cloud and configure the source and destination database information.

Section	Parameter	Description
N/A	Task Name	Configure a descriptive name that makes it easy to identify the task (no uniqueness required); you can also keep the system-generated task name.
Source Database	Database Type	Default value: SQL Server. You do not need to configure this parameter.
	Type	Select AWS.
	Access Method	Select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway based on how the 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 the Access Method parameter 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 the Access Method parameter 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	Select 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 the Access Method parameter to Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	Enter the domain name or IP address of the Amazon RDS for SQL Server instance. Note We recommend that you enter the domain name.
	Port Number	Enter the service port of the Amazon RDS for SQL Server instance.
	Database Account	Enter the database account of the Amazon RDS for SQL Server instance. For more information about the permissions that are required for the database account, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.
	Encryption	If the source database does not have Secure Sockets Layer (SSL) encryption enabled, select Non-encrypted. If the source database has SSL encryption enabled, select SSL-encrypted. DTS trusts the server certificate by default.
Destination Database	Database Type	Default value: SQL Server. You do not need to configure this parameter.
	Access Method	Default value: Alibaba Cloud Instance. You do not need to configure this parameter.
	Instance Region	The region in which the ApsaraDB RDS for SQL Server instance resides. You cannot change this value.
	Instance ID	The ID of the ApsaraDB RDS for SQL Server instance. You cannot change this value.
	Database Account	Enter the database account of the current ApsaraDB RDS for SQL Server instance, and ensure that the account has the required permissions.
	Database Password	The password that is used to access the database instance.
	Encryption	If the destination database does not have SSL encryption enabled, select Non-encrypted. If the destination database has SSL encryption enabled, select SSL-encrypted. DTS trusts the server certificate by default.

After you complete the configuration, click Test Connectivity And Proceed at the bottom of the page.
Important
Make sure that the IP addresses of DTS servers in the pop-up window are added to the whitelist of the Amazon RDS for SQL Server instance. Adding DTS IP addresses may pose security risks. Please confirm and implement appropriate protective measures (such as strengthening password security, limiting ports, etc.).
The system evaluates your source database type and generates the following two cloud migration plans for you to choose from.
- If you select the Full And Incremental Data Migration plan: Click Configure Objects at the bottom of the page and proceed to the next step.
- If you select the Data Migration Using Full And Incremental Backups plan: You do not need to proceed to the next step.
  Note
  You can click View Migration Documentation at the bottom of the page to view the corresponding cloud migration operations.

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

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 Configure how to synchronize or migrate triggers. 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 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 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 database, table, and column 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 Specify 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 advanced settings.

You can expand Advanced Settings to configure advanced parameters.

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	Full data verification uses the read resources of the database. If you select Full Data Verification, you must also set Maximum number of rows of data read per second by full verification and The maximum number of bytes read per second by full verification Byte/s. to enable throttling for full data verification (number of data rows and data volume read per second), which reduces the pressure on the database. Note A value of 0 indicates that the speed is not limited. If both Maximum number of rows of data read per second by full verification and The maximum number of bytes read per second by full verification Byte/s. are set 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 an 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.

Method 2: Use the DTS console

Log on to the Data Transmission Service (DTS) console.
In the left-side navigation pane, click Data Migration, and select the region in the upper part of the page.

Click Create Task and configure the source and destination database information.

Category	Configuration	Description
N/A	Task Name	Specify a descriptive name that makes it easy to identify the task. You can also use the task name that is automatically generated by the system.
Source Database	Select Existing Connection	If you have registered the source database information on the DTS Database Connection Management page, you can directly select the registered database here, which saves you from manually entering the source database information later.
	Database Type	Select SQL Server.
	Access Method	Based on the method used to connect Amazon RDS for SQL Server to Alibaba Cloud, select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway. In this example, Express Connect, VPN Gateway, or Smart Access Gateway is selected.
	Instance Region	When Access Method is set to Public IP Address, select the region where your Amazon RDS for SQL Server is located. 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. When Access Method is set 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 the Access Method parameter to Express Connect, VPN Gateway, or Smart Access Gateway.
	Connected VPC	Select 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 the Access Method parameter to Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	Enter the domain name or IP address of the Amazon RDS for SQL Server instance. Note We recommend that you specify the domain name.
	Port Number	Enter the service port of the Amazon RDS for SQL Server instance.
	Database Account	Enter the database account of the Amazon RDS for SQL Server instance, and make sure that the account has the required permissions.
	Database Password	The password that is used to access the database instance.
	Encryption	If Secure Sockets Layer (SSL) encryption is not enabled for the source database, select Non-encrypted. If SSL encryption is enabled for the source database, select SSL-encrypted. DTS trusts the server certificate by default.
Destination Database	Select Existing Connection	If you have registered the destination database information on the DTS Database Connection Management page, you can directly select the registered database here, which eliminates the need to manually enter the destination database information later.
	Database Type	Select SQL Server.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	Select the region to which the destination RDS SQL Server instance belongs.
	Instance ID	Select the ID of the destination RDS SQL Server instance.
	Database Account	Enter the database account of the destination ApsaraDB RDS for SQL Server instance and ensure that the account has the required permissions.
	Database Password	The password that is used to access the database instance.
	Encryption	If the destination database does not have SSL encryption enabled, select Non-encrypted. If Secure Sockets Layer (SSL) encryption is enabled for the destination database, select SSL-encrypted. DTS trusts the server certificate by default.

After the configuration is complete, click Test Connectivity And Proceed at the bottom of the page.
Important
Please ensure that the DTS server IP addresses in the pop-up box have been added to the whitelist of Amazon RDS for SQL Server. Adding DTS IP addresses may pose security risks. Please confirm and implement relevant protective measures (such as strengthening password strength, limiting ports, etc.).

Configure the objects to be migrated.

On the Configure 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 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	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 Configure how to synchronize or migrate triggers. Note You can configure this parameter only if you select both Migration Types and Schema Migration for Incremental Data Migration. 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. Note You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
The maximum number of tables for which CDC is enabled that DTS supports.	In this example, the default value is used.
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 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 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 database, table, and column 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 Specify 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 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	The environment tag that is used to identify the 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 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.
If you need to use the data verification feature, for configuration methods, see Configure a data verification task.

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 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?
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.

Appendix 1: SQL operations that support incremental migration

DML operations

INSERT, UPDATE, DELETE

Note

If an UPDATE operation updates only the large fields, DTS does not migrate the operation.

DDL operations

CREATE TABLE
Note
Partitions and table definitions that contain internal functions are not supported.
ALTER TABLE
ALTER TABLE operations include only ADD COLUMN and DROP COLUMN.
DROP TABLE
CREATE INDEX and DROP INDEX

Note

DTS does not migrate transactional DDL operations. For example, DTS does not migrate an SQL operation that contains DDL operations on multiple columns or an SQL operation that contains both DDL operations and DML operations. Data loss may occur after such SQL operations are migrated.
DTS does not migrate DDL operations that contain user-defined types.
DTS does not migrate online DDL operations.
DTS does not migrate DDL operations performed on objects whose names contain reserved keywords.
DTS does not migrate DDL operations performed in system stored procedures.
DTS does not migrate the TRUNCATE TABLE operation.

Appendix 2: Objects that can be migrated during schema migration

DTS supports schema migration for the following types of objects: table, view, trigger, synonym, SQL stored procedure, SQL function, plan guide, user-defined type, rule, default, and sequence.
DTS does not migrate the schemas of assemblies, service brokers, full-text indexes, full-text catalogs, distributed schemas, distributed functions, Common Language Runtime (CLR) stored procedures, CLR scalar-valued functions, CLR table-valued functions, internal tables, systems, or aggregate functions.

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.