Migrating SQL Server from AWS to Alibaba Cloud - Data Transmission Service

Background information

This topic provides two methods for migrating Amazon RDS for SQL Server to the cloud. You can select a method based on your actual needs.

Use the RDS one-stop cloud migration feature

The RDS console provides a one-stop cloud migration feature to help you migrate data from Amazon RDS for SQL Server to Alibaba Cloud RDS for SQL Server quickly and easily.

Note
By default, this method includes schema migration, full data migration, and incremental migration tasks.
Use DTS to migrate to the cloud

DTS supports cloud migration through its data migration feature. Compared with the RDS one-stop cloud migration feature, DTS lets you select specific migration task types—such as schema migration, full data migration, and incremental migration—and configure more advanced parameters.

Prerequisites

You have connected the Amazon RDS for SQL Server database to Alibaba Cloud so that DTS can connect to the source database. For more information, see Connect databases from the AWS platform to Alibaba Cloud.
You have created a target RDS SQL Server instance with storage capacity greater than that of the source database. For more information, see Quickly create and use an RDS SQL Server instance.

Important notes

Note

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

SQL operations supported for incremental migration

Operation type	SQL statement
DML	INSERT, UPDATE, DELETE
DDL	CREATE TABLE ALTER TABLE Only ADD COLUMN and DROP COLUMN are supported. DROP TABLE CREATE INDEX, DROP INDEX Note DTS does not support transactional DDL operations. For example, adding multiple columns in a single SQL statement or combining DDL and DML in one statement may cause data loss. DTS does not support DDL operations that use custom data types. DTS does not support online DDL operations. DTS does not support DDL operations that use reserved keywords as column names. DTS does not support DDL operations executed by system stored procedures. DTS does not support TRUNCATE TABLE operations. DTS does not support partitions or table definitions that contain functions.

Database account permissions

Database	Schema migration	Full migration	Incremental migration	How to create and grant permissions
Amazon RDS for SQL Server	SELECT permission	SELECT permission	db_owner permission Note RDS for SQL Server's privileged account meets the requirements and supports enabling database-level CDC for stored procedures.	For specific steps, contact AWS.
RDS for SQL Server instance	Read and write permission			Create standard, privileged, and global read-only accounts and Modify account permissions.

Procedure

Use the RDS one-stop cloud migration feature

Go to the Data Migration tab of the target RDS for SQL Server instance.
1. Go to the RDS Instance List.
2. In the upper part of the page, select the region where the target RDS for SQL Server instance resides.
3. Click the ID of the target RDS for SQL Server instance.
4. In the navigation pane on the left, click Data Migration and Synchronization.
5. Click the Data Migration tab.
Click One-Stop Cloud Migration.

Configure source and destination database information.

Category	Configuration	Description
None	Task Name	The system generates a task name by default. We recommend specifying a meaningful name (not required to be unique) for easier identification later.
Source Database	Database Type	By default, this is set to SQL Server. You do not need to select it.
	Type	Select AWS.
	Access Method	Select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway based on how Amazon RDS for SQL Server connects to Alibaba Cloud. This example selects Express Connect, VPN Gateway, or Smart Access Gateway.
	Instance Region	When the Access Method is set to Public IP Address, select the region where the RDS for SQL Server instance resides. Note If the region where Amazon RDS for SQL Server is located does not appear in the options, you can select a region closest to that database. When the Access Method is set to Express Connect, VPN Gateway, or Smart Access Gateway, select the region where the Alibaba Cloud Virtual Private Cloud (VPC) for the Amazon RDS for SQL Server connection is located.
	Connected VPC	Select the ID of the Alibaba Cloud Virtual Private Cloud (VPC) connected to Amazon RDS for SQL Server. Note This option appears only when you select Access Method as Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	Enter the domain name or IP address of Amazon RDS for SQL Server. Note We recommend entering the domain name.
	Port Number	Enter the service port of Amazon RDS for SQL Server.
	Database Account	Enter the database account for Amazon RDS for SQL Server. For more information, see Permission requirements for database accounts.
	Database Password	Enter the password for the database account.
	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	By default, this is set to SQL Server. You do not need to select it.
	Access Method	By default, this is set to Alibaba Cloud Instance. You do not need to select it.
	Instance Region	This is fixed to the region of the current RDS for SQL Server instance and cannot be changed.
	Instance ID	This is fixed to the ID of the current RDS for SQL Server instance and cannot be changed.
	Database Account	Enter the database account of the current RDS for SQL Server instance. For permission requirements, see Database account permissions.
	Database Password	Enter the password for the database account.
	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.

After configuration, click Test Connectivity and Proceed at the bottom of the page.

Ensure that the DTS server IP address shown in the pop-up dialog box is added to the whitelist security settings of your Amazon RDS for SQL Server. Then click Test Connectivity.

Important
Adding the public IP address range of DTS servers may pose security risks. Using this product means you understand and accept these risks. You must implement basic security measures, such as strengthening account password strength, limiting open ports for each CIDR block, using authentication for internal API communication, and regularly reviewing and restricting unnecessary CIDR blocks. For more information, see Add DTS server IP addresses to the whitelist.
Select a migration plan.

The system evaluates your source database type and presents two cloud migration plans.
- To select the Full and Incremental Data Migration plan, click Configure Objects at the bottom of the page and continue to the next step.
- To select the Full and Incremental Backup-Based Data Migration plan, no further action is needed.
  
  Note
  You can click View Migration Documentation at the bottom of the page to view the corresponding cloud migration steps.

On the Configure Objects page, configure the objects to migrate.

Configuration	Description
Method to Migrate Triggers in Source Database	During incremental data migration, triggers may migrate to the destination database too early, causing data inconsistency between the source and destination databases. Choose a trigger migration method based on your needs. We recommend selecting Manual Migration. For more information, see Configure trigger migration or synchronization. Note If your objects do not include triggers, skip this step (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 You can select databases, tables, or columns as migration objects. If you select tables or columns, other objects (such as views, triggers, and stored procedures) are not migrated to the destination database.
Selected Objects	To change the name of a migration object in the destination instance, right-click the object in the Selected Objects box and edit it. For instructions, see Map database, table, and column names. To remove a selected migration object, click the object in the Selected Objects box, then click to move it back to the Source Objects box. Note Using the object name mapping feature may cause migration failures for objects that depend on the mapped object. To filter data using a WHERE clause, right-click the table to migrate in the Selected Objects box, then set the filter condition in the dialog box. For instructions, see Set filter conditions. To select SQL operations to migrate at the database or table level, right-click the object to migrate in the Selected Objects box and select the required SQL operations in the dialog box.

Optional: Configure advanced settings.

You can expand advanced settings to configure advanced parameters.

Configuration	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 validation consumes some read resources from the database. If you select Full Data Verification, you must also 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 full validation rate (rows and data volume per second) and reduce database load. Note A value of 0 means 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 0, there is no rate limit.

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.

Use DTS to migrate to the cloud

Go to the migration task list page for the destination region.
1. Log on to the Data Transmission Service (DTS) console.
2. In the navigation pane on the left, click Data Migration.
3. In the upper-left corner of the page, select the region where the instance resides.
Click Create Task to navigate to the task configuration page.

Configure the source and destination databases.

Category	Configuration	Description
None	Task Name	DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.
Source Database	Select Existing Connection	You can choose whether to use an existing instance based on your needs. If you use an existing instance, the database information below is filled in automatically. You do not need to enter it again. If you do not use an existing instance, you must enter the database information below. Note You can register databases in DTS on the Database Connections page or the new configuration page. For more information, see Data Connection Management.
	Database Type	Select SQL Server.
	Access Method	Select Public IP Address or Express Connect, VPN Gateway, or Smart Access Gateway based on how Amazon RDS for SQL Server connects to Alibaba Cloud. This example selects Express Connect, VPN Gateway, or Smart Access Gateway.
	Instance Region	When the Access Method is set to Public IP Address, select the region where the RDS for SQL Server instance resides. Note If the region where Amazon RDS for SQL Server is located does not appear in the options, you can select a region closest to that database. When the Access Method is set to Express Connect, VPN Gateway, or Smart Access Gateway, select the region where the Alibaba Cloud Virtual Private Cloud (VPC) for the Amazon RDS for SQL Server connection is located.
	Replicate Data Across Alibaba Cloud Accounts	In this example, a database instance under the current Alibaba Cloud account is used. Select No. Note This option appears only when you select Access Method as Express Connect, VPN Gateway, or Smart Access Gateway.
	Connected VPC	Select the ID of the Alibaba Cloud Virtual Private Cloud (VPC) connected to Amazon RDS for SQL Server. Note This option appears only when you select Access Method as Express Connect, VPN Gateway, or Smart Access Gateway.
	Domain Name or IP	Enter the domain name or IP address of Amazon RDS for SQL Server. Note We recommend entering the domain name.
	Port Number	Enter the service port for Amazon RDS for SQL Server.
	Database Account	Enter the database account for Amazon RDS for SQL Server. For permission requirements, see Permission requirements for the database account.
	Database Password	Enter the password for the database account.
	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	You can choose whether to use an existing instance based on your needs. If you use an existing instance, the database information below is filled in automatically. You do not need to enter it again. If you do not use an existing instance, you must enter the database information below. Note You can register databases in DTS on the Database Connections page or the new configuration page. For more information, see Data Connection Management.
	Database Type	Select SQL Server.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	Select the region where the destination RDS for SQL Server instance resides.
	Instance ID	Select the ID of the destination RDS for SQL Server instance.
	Database Account	Enter the database account of the destination RDS for SQL Server instance. For permission requirements, see Database account permissions.
	Database Password	Enter the password for the database account.
	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.

After configuration, click Test Connectivity and Proceed at the bottom of the page.

Ensure that the DTS server IP address shown in the pop-up dialog box is added to the whitelist security settings of your Amazon RDS for SQL Server. Then click Test Connectivity.

Important
Adding the public IP address range of DTS servers may pose security risks. Using this product means you understand and accept these risks. You must implement basic security measures, such as strengthening account password strength, limiting open ports for each CIDR block, using authentication for internal API communication, and regularly reviewing and restricting unnecessary CIDR blocks. For more information, see Add DTS server IP addresses to the whitelist.

Configure the task objects.

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

Configuration	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	During incremental data migration, triggers may migrate to the destination database too early, causing data inconsistency between the source and destination databases. Choose a trigger migration method based on your needs. We recommend selecting Manual Migration. For more information, see Configure trigger migration or synchronization. Note You can configure this only when you select both Migration Types options: Schema Migration and Incremental Data Migration. If your objects do not include triggers, skip this step (keep the default setting).
SQL Server Incremental Synchronization Mode	Select Polling and querying CDC instances for incremental synchronization. Note This option appears only when Migration Types includes Incremental Data Migration.
The maximum number of tables for which CDC is enabled that DTS supports.	In this example, 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 You can select databases, tables, or columns as migration objects. If you select tables or columns, other objects (such as views, triggers, and stored procedures) are not migrated to the destination database.
Selected Objects	To change the name of a migration object in the destination instance, right-click the object in the Selected Objects box and edit it. For instructions, see Map database, table, and column names. To remove a selected migration object, click the object in the Selected Objects box, then click to move it back to the Source Objects box. Note Using the object name mapping feature may cause migration failures for objects that depend on the mapped object. To filter data using a WHERE clause, right-click the table to migrate in the Selected Objects box, then set the filter condition in the dialog box. For instructions, see Set filter conditions. To select SQL operations to migrate at the database or table level, right-click the object to migrate in the Selected Objects box and select the required SQL operations in the dialog box.

Click Next: Advanced Settings to configure advanced parameters.

Configuration	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 label to identify the instance. In this example, no selection is needed.
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 notifications. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

Click Next: Data Validation to configure the data validation task.

If you want to use data validation, see Configure data validation for instructions.

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.

FAQ

Does the one-stop cloud migration feature of RDS support selecting objects for validation?
No, it does not. By default, the objects for validation are the same as the objects for migration.
What is the mode for full validation in the one-stop cloud migration feature of RDS?
The mode is HASH validation with a 100% sampling rate.
What is the baseline for full validation in the one-stop cloud migration feature of RDS?
The union of the source and destination databases is used as the baseline to validate data consistency between them.