SQL Server cloud migration on AWS-ApsaraDB RDS(RDS)-阿里云帮助中心

Prerequisites

You have created a target ApsaraDB RDS for SQL Server instance with more storage space than the source database.
You have connected the Amazon RDS for SQL Server database to Alibaba Cloud so DTS can connect to the source database.
The source database version must meet the following requirements:
- Enterprise edition: SQL Server 2008 or later.
- Standard edition: Must be SQL Server 2016 SP1 or later.
- SQL Server 2017 (both standard and enterprise editions): We recommend upgrading to a later version.

Precautions

Review the following key precautions before migration. Otherwise, the task may fail or report errors:

Database limit: You can migrate a maximum of 10 databases in a single migration task. Exceeding this limit may cause instability and performance issues.
Table limit: For tasks that include incremental migration, you cannot synchronize more than 1,000 tables from the source database. Exceeding this limit may cause task latency or instability.
Source database operation restrictions: During the schema migration and full migration phases, do not perform DDL operations, such as altering a database or table schema. Otherwise, the migration task will fail.
CDC-related limitations: If CDC is enabled for tables in the source database and the data in a single field exceeds 64 KB, you must run the EXEC sp_configure 'max text repl size', -1; command to adjust the configuration. Otherwise, the migration task may fail.
Table schema requirements: Each table you migrate must have a primary key or a unique constraint, and the values in the key columns must be unique. Otherwise, duplicate data may occur in the destination database.
Foreign keys and triggers: For tasks that include incremental migration, you must disable any enabled triggers and foreign keys in the destination database. Otherwise, the task may fail or result in data loss.
Database naming conventions: If the name of the database to be migrated does not conform to the naming conventions of RDS SQL Server, you must manually create the database in the destination RDS SQL Server instance before you configure the migration task. Otherwise, the task may not run as expected.
Transaction log retention period: For an incremental migration task, the transaction logs of the source database must be retained for more than 24 hours. For a task that includes both full and incremental migration, the transaction logs must be retained for at least 7 days. Otherwise, the task may fail or cause data inconsistencies.

Limitations and precautions

Note

DTS does not migrate foreign keys from the source database to the destination database. As a result, DTS does not migrate cascading operations from the source database.

Type	Description
Source database limits	The source database version has the following limits: If the source database is an Enterprise Edition instance, its version must be 2008 or later. If the source database is a Standard Edition instance, its version must be 2016 SP1 or later. If the source database is a SQL Server 2017 instance (Standard Edition or Enterprise Edition), upgrade the instance. 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. A single data migration task supports a maximum of 10 databases. If you exceed this limit, stability and performance issues may occur. In this case, split the databases into multiple migration tasks. If you configure a task to migrate specific objects instead of an entire database, you cannot migrate tables that have the same name but different schema names to the same destination database. For an incremental migration task, DTS requires that the data logs of the source database are retained for more than 24 hours. For a task that includes both full migration and incremental migration, DTS requires that the data logs of the source database are retained for at least 7 days. You can change the log retention period to more than 24 hours after the full migration is complete. Otherwise, the DTS task may fail because DTS cannot obtain the data logs. In extreme cases, data inconsistency or data loss may occur. Issues caused by a log retention period that is shorter than the required period are not covered by the DTS SLA. Source database operation limits: During initial schema synchronization and full data migration, do not perform DDL operations to change the schemas of databases or tables. Otherwise, the data migration task fails. If you perform only full data migration, do not write new data to the source instance. Otherwise, data inconsistency occurs between the source and destination databases. To ensure real-time data consistency, select Initial Schema Synchronization, Full Data Migration, and Incremental Data Migration. Read-only instances are not supported as the source database. If you use the `sp_rename` command to rename objects such as stored procedures in the source database before the initial schema synchronization task runs, the task may not work as expected or may fail. Note Use the `ALTER` command to rename objects in the database. During full data migration, make sure that the `READ_COMMITTED_SNAPSHOT` transaction processing mode parameter is enabled for the source database. This prevents shared locks from affecting data writes. Otherwise, exceptions such as data inconsistency and instance failures may occur. Exceptions caused by this issue are not covered by the DTS SLA.
Other limits	Data of the CURSOR, ROWVERSION, SQL_VARIANT, HIERARCHYID, POLYGON, GEOMETRY, and GEOGRAPHY data types cannot be migrated. To migrate triggers from the source database, the database account used for the task must have Owner permissions on the destination database. If data cannot be written to a field of the TIMESTAMP data type in the destination database, DTS does not support full and incremental migration. This may cause data inconsistency or task failures. The prerequisite module of an incremental migration task enables CDC for the source database. During this process, the source database may be briefly locked due to the limits of the SQL Server database kernel. Incremental migration tasks migrate incremental data by polling CDC instances. Therefore, the following limits apply: DTS polls the CDC instance of each table in the source database to obtain incremental data. Therefore, you cannot synchronize more than 1,000 tables from the source database. Otherwise, task latency or instability may occur. By default, the incremental data stored in the CDC component is retained for 3 days. We recommend that you use the `exec console.sys.sp_cdc_change_job @job_type = 'cleanup', @retention= <time>;` command to adjust the retention period. Note `<time>` specifies the time in minutes. If the number of incremental change SQL statements for a single table in the source database exceeds 10 million per day, we recommend that you set `<time>` to 1440. You cannot consecutively perform operations to add or remove columns. For example, you cannot perform more than two DDL operations to add or remove columns within one minute. Otherwise, the task may fail. You cannot change the CDC instance of the source database. Otherwise, the task may fail or data may be lost. In scenarios where you migrate multiple databases and tables, stability and performance issues may occur. Incremental data migration has a latency of about 10 seconds. If you migrate data across different versions, check the compatibility in advance. If a migration task includes incremental data migration, you cannot reindex. You must also disable the triggers and foreign keys that are enabled in the destination database. Otherwise, the task may fail or data may be lost. Note You cannot change the primary keys of tables for which CDC is enabled. If the number of tables for which CDC is enabled in a single migration task is greater than 1,000 (or greater than the value of The maximum number of tables for which CDC is enabled that DTS supports.), the precheck fails. If a task includes incremental migration and the data to be written to a single field of a table with CDC enabled exceeds 64 KB, you must run the `exec sp_configure 'max text repl size', -1;` command to adjust the configuration of the source database in advance. Note By default, a CDC job can process a single field with a maximum length of 64 KB. DTS automatically creates a database in the RDS for SQL Server instance. If the name of the database to be migrated does not comply with the naming conventions of RDS for SQL Server, you must create a database in the destination instance before you configure the migration task. For more information, see Create a database. To ensure the accuracy of incremental data migration latency, DTS creates the dts_cdc_sync_ddl trigger, the dts_sync_progress heartbeat table, and the dts_cdc_ddl_history DDL storage table in the source database in log parsing mode. In hybrid incremental synchronization mode, DTS creates the dts_cdc_sync_ddl trigger, the dts_sync_progress heartbeat table, and the dts_cdc_ddl_history DDL storage table, and enables database-level CDC and CDC for some tables. We recommend that the data change rate of tables with CDC enabled in the source database does not exceed 1,000 RPS. Before you migrate data, evaluate the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. Otherwise, DTS consumes read and write resources on the source and destination databases during full data migration, which may increase the database load. Full data migration involves concurrent INSERT operations, which cause table fragmentation in the destination database. Therefore, after full data migration is complete, the table storage space in the destination database is larger than that in the source instance. Confirm whether the migration precision that DTS provides for columns of the FLOAT or DOUBLE data type meets your business requirements. DTS reads the values of these columns using `ROUND(COLUMN,PRECISION)`. If you do not specify the precision, DTS migrates FLOAT values with a precision of 38 and DOUBLE values with a precision of 308. DTS attempts to resume a failed migration task within seven days. Therefore, before you switch your business to the destination instance, you must end or release the task, or use the `revoke` command to revoke the write permissions of the account that DTS uses to access the destination instance. This prevents the source data from overwriting the data in the destination instance after the task is automatically resumed. If multiple DTS instances use the same SQL Server database as the source, their incremental data ingestion modules are independent of each other. If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters. Note Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters. SQL Server is a commercial closed-source database. Due to known or unknown format-specific limits, issues may occur when DTS performs CDC and parsing on SQL Server logs. Therefore, before you enable incremental synchronization or migration for a SQL Server source in a production environment, we recommend that you perform a comprehensive proof of concept (POC) test. The test must cover all business change types, table schema changes, and business peak-hour stress tests. Due to the unpredictable nature of the SQL Server log format, you must ensure that the business logic in the production environment is consistent with that in the POC test. This is key to ensuring the high efficiency and stability of DTS.

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.

Database account permissions

For a successful data migration, ensure the database accounts for the source and destination databases have the following permissions:

Amazon RDS for SQL Server

Schema migration: Requires SELECT privilege.
Full data migration: Requires SELECT permissions.
Incremental migration: Requires the dbower permission (to enable the CDC feature).

Note

A high-privilege account for Amazon RDS for SQL Server meets these requirements. For more information, see the AWS platform documentation or contact technical support.

RDS SQL Server instance

Structure migration, full migration, and incremental migration: require read and write permissions.

Note

You can use the RDS console to create a standard account or a high-privilege account and modify account permissions as needed.

Procedure

The one-stop cloud migration feature on the RDS console provides a simple process, migrating table structure, full data, and incremental data by default. In contrast, the migration feature on the DTS console supports custom migration types and advanced parameters but requires a more complex setup.

Method 1: One-stop migration on the RDS console

Go to the RDS Instance List page, select a region at the top, and then click the ID of the destination instance.
In the navigation pane on the left, click Data Migration and Synchronization to go to the Data Migration page.

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

Category	Parameter	Description
None	Task Name	Enter a descriptive name to easily identify the task. The name does not need to be unique. Alternatively, you can use the system-generated name.
Source Database	Database Type	This field defaults to SQL Server and cannot be changed.
	Type	Select AWS.
	Access Method	Select how your Amazon RDS for SQL Server instance connects to Alibaba Cloud: Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway. This example uses Express Connect, VPN Gateway, or Smart Access Gateway.
	Instance Region	When Access Method is Public IP Address, select the region where the Amazon RDS for SQL Server instance is located. Note If the region where your Amazon RDS for SQL Server instance is located is not available in the dropdown list, select the region that is geographically closest to your instance. When Access Method is Express Connect, VPN Gateway, or Smart Access Gateway, select the region of the Virtual Private Cloud (VPC) that connects your Amazon RDS for SQL Server instance to Alibaba Cloud.
	Connected VPC	Select the ID of the Alibaba Cloud Virtual Private Cloud (VPC) that connects to the Amazon RDS for SQL Server instance. Note This parameter is available only when Access Method is set 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 for the Amazon RDS for SQL Server instance. For permission requirements, see Database account permissions.
	Database Password	Enter the password for the database account.
	Encryption	If SSL encryption is disabled on the source database, select Non-encrypted. If SSL encryption is enabled on the source database, select SSL-encrypted. DTS trusts the server certificate by default.
Destination Database	Database Type	This field defaults to SQL Server and cannot be changed.
	Access Method	This field defaults to Alibaba Cloud Instance and cannot be changed.
	Instance Region	The region where the RDS SQL Server instance is located. This parameter cannot be changed.
	Instance ID	The ID of the RDS SQL Server instance. This parameter cannot be changed.
	Database Account	Enter the database account for the RDS SQL Server instance and ensure that the account has the required permissions.
	Database Password	Enter the password for the database account.
	Encryption	If SSL encryption is disabled on the destination database, select Non-encrypted. If SSL encryption is enabled on the destination database, select SSL-encrypted. DTS trusts the server certificate by default.

After you complete the configuration, click Test Connection and Proceed at the bottom of the page.

Important
Add the DTS server IP addresses displayed in the dialog box to the allowlist of your Amazon RDS for SQL Server instance. Note that adding DTS IP addresses can introduce security risks. Before proceeding, confirm that you understand these risks and have taken protective measures, such as using strong passwords and restricting port access.
The system evaluates your source database and proposes the following two migration solutions:
- If you choose the Full and Incremental Data Migration solution, click Configure Objects at the bottom of the page to continue.
- If you choose the Data Migration Using Full and Incremental Backups solution, no further steps are required.
  
  Note
  You can click View Migration Documentation at the bottom of the page for detailed instructions.

On the Configure Objects page, configure the migration objects.

Parameter	Description
Method to Migrate Triggers in Source Database	Migrating triggers too early during an incremental data migration can cause data inconsistency between the source and target databases. Select a migration method based on your business needs. We recommend selecting Manual Migration. For more information, see Configure the synchronization or migration method for triggers. Note If the objects to be migrated do not involve triggers, you can keep the default setting.
Source Objects	In the Source Objects box, click the objects to migrate, and then click to move them to the Selected Objects box. Note Migration objects can be selected at the database, table, or column level. If you select only tables or columns, other object types such as views, triggers, and stored procedures are not migrated.
Selected Objects	To change the name of a migration object in the target instance, right-click the object in the Selected Objects pane and modify its name. For more information, see Map database, table, and column names. To remove a selected object, click the object in the Selected Objects pane, and then click to move it back to the Source Objects pane. Note If you use object name mapping, the migration of dependent objects may fail. To filter data by using a WHERE clause, right-click a table in the Selected Objects pane and set the filter condition in the dialog box that appears. For more information, see Set filter conditions. To select the SQL operations to migrate at the database or table level, right-click a migration object in the Selected Objects pane and select the desired SQL operations in the dialog box that appears.

Optional: Configure advanced settings.

Parameter	Description
Enable Throttling for Full Data Migration	During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database.
Enable Throttling for Incremental Data Migration	If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database.
Data Verification Mode	Full data verification consumes read resources from the database. If you select Full Data Verification, you also need to set Maximum number of rows of data read per second by full verification (RPS) and Maximum amount of data read per second by full verification (MBps) to limit the rate of the verification task and reduce the load on the database. Note A value of 0 indicates no limit. If both Maximum number of rows of data read per second by full verification (RPS) and Maximum amount of data read per second by full verification (MBps) are set to 0, no rate limit is applied.

Save the task and run a precheck.
- To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.
- If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.
Note
- Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.
- If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.
- If a warning is reported during the precheck:
  
  For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.
  
  For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.
When the Success Rate is 100%, click Next: Purchase Instance.

Purchase the instance.

On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

Category	Parameter	Description
New Instance Class	Resource Group Settings	Select the resource group to which the instance belongs. The default value is default resource group. For more information, see What is Resource Management?
New Instance Class	Instance Class	DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start. In the OK dialog box that appears, click OK.

You can view the progress of the migration task on the Data Migration Tasks list page.
Note
- If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.
- If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.

Method 2: Migrate with DTS

Go to the Data Transmission Service (DTS) console.
In the left navigation pane, click Data Migration, and select a region at the top of the page.

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

Category	Parameter	Description
None	Task Name	Enter a descriptive name to easily identify the task. The name does not have to be unique. You can also use the system-generated name.
Source Database	Select Existing Connection	If you have saved the source database connection details in DTS Data Connection Management, you can select the saved connection to autofill the configuration.
	Database Type	Select SQL Server.
	Access Method	Based on how your Amazon RDS for SQL Server instance connects to Alibaba Cloud, select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway. This example uses Express Connect, VPN Gateway, or Smart Access Gateway.
	Instance Region	If Access Method is set to Public IP Address: Select the region where your Amazon RDS for SQL Server instance is located. Note If the region of your Amazon RDS for SQL Server instance is not available as an option, you can select the region that is geographically closest to your database. If Access Method is set to Express Connect, VPN Gateway, or Smart Access Gateway: Select the region of the Alibaba Cloud Virtual Private Cloud (VPC) connected to your Amazon RDS for SQL Server instance.
	Replicate Data Across Alibaba Cloud Accounts	In this example, a database instance under the current Alibaba Cloud account is used. Select No. Note This parameter is available only when Access Method is set to Express Connect, VPN Gateway, or Smart Access Gateway.
	Connected VPC	Select the ID of the Alibaba Cloud Virtual Private Cloud (VPC) that is connected to the Amazon RDS for SQL Server instance. Note This parameter is available only when Access Method is set 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 for the Amazon RDS for SQL Server instance and ensure that the account has the required permissions.
	Database Password	Enter the password for the database account.
	Encryption	If SSL encryption is not enabled on the source database, select Non-encrypted. If SSL encryption is enabled on the source database, select SSL-encrypted. DTS trusts the server-side certificate by default.
Destination Database	Select Existing Connection	If you have saved the target database connection details in DTS Data Connection Management, you can select the saved connection to autofill the configuration.
	Database Type	Select SQL Server.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	Select the region where the target RDS SQL Server instance is located.
	Instance ID	Select the ID of the target RDS SQL Server instance.
	Database Account	Enter the database account for the target RDS SQL Server instance and ensure that the account has the required permissions.
	Database Password	Enter the password for the database account.
	Encryption	If SSL encryption is not enabled on the target database, select Non-encrypted. If SSL encryption is enabled on the target database, select SSL-encrypted. DTS trusts the server-side certificate by default.

After you complete the configuration, click Test Connection and Proceed at the bottom of the page.

Important
Add the DTS server IP addresses displayed in the dialog box to the allowlist of your Amazon RDS for SQL Server instance. Be aware that Adding DTS IP addresses may pose security risks. Before proceeding, ensure you understand these risks and have taken protective measures, such as using strong passwords and restricting port access.

Configure the task objects.

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

Parameter	Description
Migration Types	If you only need to perform a full migration, select both Schema Migration and Full Data Migration. To perform a migration with no downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Schema Migration, you must ensure that a database and tables to receive the data exist in the destination database. You can also use the object name mapping feature in the Selected Objects box as needed. If you do not select Incremental Data Migration, do not write new data to the source instance during data migration to ensure data consistency.
Method to Migrate Triggers in Source Database	Migrating triggers too early during an incremental data migration can cause data inconsistency between the source and target databases. Select a migration method based on your business needs. We recommend selecting Manual Migration. For more information, see Configure the synchronization or migration method for triggers. Note This parameter can be configured only when both Migration Types and Incremental Data Migration are selected for Schema Migration. If the objects you want to migrate do not involve triggers, you can keep the default setting.
SQL Server Incremental Synchronization Mode	Select Polling and querying CDC instances for incremental synchronization. Note This parameter is available only when Migration Types includes Incremental Data Migration.
The maximum number of tables for which CDC is enabled that DTS supports.	For this example, you can keep the default value.
Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks whether tables with the same names exist in the destination database. If no tables with the same names exist, the precheck is passed. If tables with the same names exist, an error is reported during the precheck, and the data migration task does not start. Note If a table in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the table in the destination database. For more information, see Object name mapping. Ignore Errors and Proceed: Skips the check for tables with the same names. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example: If the table schemas are consistent and a record in the destination database has the same primary key value as a record in the source database: During full migration, DTS keeps the record in the destination database. The record from the source database is not migrated. During incremental migration, DTS does not keep the record in the destination database. The record from the source database overwrites the record in the destination database. If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.
Capitalization of Object Names in Destination Instance	You can configure the case sensitivity policy for the names of migrated objects, such as databases, tables, and columns, in the destination instance. By default, DTS default policy is selected. You can also choose to keep the case sensitivity consistent with the default policy of the source or destination database. For more information, see Case sensitivity of object names in the destination database.
Source Objects	In the Source Objects box, click the objects to migrate, and then click to move them to the Selected Objects box. Note Migration objects can be selected at the database, table, or column level. If you select only tables or columns, other object types such as views, triggers, and stored procedures are not migrated.
Selected Objects	To change the name of a migration object in the target instance, right-click the object in the Selected Objects pane and modify its name. For more information, see Map database, table, and column names. To remove a selected object, click the object in the Selected Objects pane, and then click to move it back to the Source Objects pane. Note If you use object name mapping, the migration of dependent objects may fail. To filter data by using a WHERE clause, right-click a table in the Selected Objects pane and set the filter condition in the dialog box that appears. For more information, see Set filter conditions. To select the SQL operations to migrate at the database or table level, right-click a migration object in the Selected Objects pane and select the desired SQL operations in the dialog box that appears.

Click Next: Advanced Settings to configure advanced parameters.

Parameter	Description
Dedicated Cluster for Task Scheduling	By default, DTS schedules tasks on a shared cluster. You do not need to select one. If you want more stable tasks, you can purchase a dedicated cluster to run DTS migration tasks.
Retry Time for Failed Connections	After the migration task starts, if the connection to the source or destination database fails, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1440 minutes. We recommend that you set the duration to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails. Note For multiple DTS instances that share the same source or destination, the network retry time is determined by the setting of the last created task. Because you are charged for the task during the connection retry period, we recommend that you customize the retry time based on your business needs, or release the DTS instance as soon as possible after the source and destination database instances are released.
Retry Time for Other Issues	After the migration task starts, if a non-connectivity issue, such as a DDL or DML execution exception, occurs in the source or destination database, DTS reports an error and immediately begins to retry the operation. The default retry duration is 10 minutes. You can customize the retry time to a value from 1 to 1440 minutes. We recommend that you set the duration to more than 10 minutes. If the related operations succeed within the specified retry duration, the migration task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than the value of Retry Time for Failed Connections.
Enable Throttling for Full Data Migration	During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Full Data Migration for Migration Types. You can also adjust the full migration speed after the migration instance is running.
Enable Throttling for Incremental Data Migration	If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Incremental Data Migration for Migration Types. You can also adjust the incremental migration speed after the migration instance is running.
Environment Tag	You can select an environment tag to identify the instance based on your business requirements. No selection is needed for this example.
Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
Monitoring and Alerting	Select whether to set alerts and receive alert notifications based on your business needs. No: Does not set an alert. Yes: Configure alerts by setting an alert threshold and an alert contact. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

Click Next: Data Verification.

If you want to use the data verification feature, see Configure data verification.

Save the task and run a precheck.
- To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.
- If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.
Note
- Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.
- If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.
- If a warning is reported during the precheck:
  
  For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.
  
  For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.

Purchase the instance.

When the Success Rate is 100%, click Next: Purchase Instance.

On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

Category	Parameter	Description
New Instance Class	Resource Group Settings	Select the resource group to which the instance belongs. The default value is default resource group. For more information, see What is Resource Management?
New Instance Class	Instance Class	DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start. In the OK dialog box that appears, click OK.

You can view the progress of the migration task on the Data Migration Tasks list page.
Note
- If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.
- If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.

Appendix 1: Supported SQL for incremental migration

DML operations

INSERT, UPDATE, DELETE

Note

Incremental migration does not support UPDATE statements that only update large fields.

DDL operations

CREATE TABLE

Note
Partitions and functions within a table definition are not supported.
ALTER TABLE

Only ADD COLUMN and DROP COLUMN are supported.
DROP TABLE
CREATE INDEX, DROP INDEX

Note

Transactional DDL operations are not supported. For example, a single statement that adds multiple columns or mixes DDL and DML operations can cause data loss.
DDL operations on user-defined types are not supported.
Online DDL operations are not supported.
DDL operations that use a reserved keyword as an identifier are not supported.
DDL operations executed by a system stored procedure are not supported.
TRUNCATE TABLE operations are not supported.

Appendix 2: Objects supported in schema migration

Supported object types: table, view, trigger, synonym, SQL stored procedure, SQL function, plan guide, user-defined type, rule, default, sequence.

Not supported: assemblies, service brokers, full-text indexes, full-text catalogs, distributed schemas, distributed functions, CLR stored procedures, CLR scalar-valued functions, CLR table-valued functions, internal tables, systems, aggregate functions.

FAQ

Can I select verification objects for ApsaraDB RDS One-Stop Cloud Migration?

No. By default, the verification objects are the same as the migration objects.
How is full data verification performed for ApsaraDB RDS One-Stop Cloud Migration?

The process uses HASH verification at a 100% sampling ratio.
What is the benchmark for full data verification in ApsaraDB RDS One-Stop Cloud Migration?

It uses the union of data from the source and destination databases as the benchmark to verify data consistency.