Data Transmission Service:Synchronize data between ApsaraDB RDS for MySQL instances of different Alibaba Cloud accounts

Prerequisites

• The source and destination ApsaraDB RDS for MySQL instances are created. For more information, see Create an ApsaraDB RDS for MySQL instance.

• The available storage space of the destination ApsaraDB RDS for MySQL instance is larger than the total size of the data in the source ApsaraDB RDS for MySQL instance.

Usage notes

• DTS uses read and write resources of the source and destination RDS instances during initial full data synchronization. This may increase the loads of the RDS instances. If the instance performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source RDS instance, the tables have no primary keys, or a deadlock occurs in the destination RDS instance. Before data synchronization, evaluate the impact of data synchronization on the performance of the source and destination RDS instances. We recommend that you synchronize data during off-peak hours. For example, you can synchronize data when the CPU utilization of the source and destination RDS instances is less than 30%.

• The tables to be synchronized in the source database must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, the destination database may contain duplicate data records.

• During initial full data synchronization, concurrent INSERT operations cause fragmentation in the tables of the destination instance. After initial full data synchronization is complete, the tablespace of the destination instance is larger than that of the source instance.

• Data synchronization across Alibaba Cloud accounts and regions is supported. Two-way synchronization across Alibaba Cloud accounts is supported only between ApsaraDB RDS for MySQL instances.

• After the operations described in the "Preparations" section are complete, you can obtain the information about database instances within the Alibaba Cloud accounts to which the source and destination instances belong.

  Important

  We recommend that you delete the Resource Access Management (RAM) role that you create during preparations at the earliest opportunity after the data synchronization task is complete.

• If your destination instance is not an ApsaraDB RDS for MySQL instance, operations across Alibaba Cloud accounts are not supported.

• The source Apsara RDS for MySQL instance cannot be a read-only ApsaraDB RDS for MySQL instance that does not record transaction logs, such as an ApsaraDB RDS for MySQL V5.6 instance.

• Column names in MySQL databases are not case-sensitive. Therefore, if multiple columns in the source database have the same name that differs only in capitalization, data in the columns are written to the same column in the destination MySQL database during the synchronization. This can cause unexpected synchronization results.

• After data synchronization is complete, we recommend that you run the analyze table <Table name> command to check whether data has been written to the destination table. For example, after a high-availability switchover is triggered in the source MySQL database, data may be written only to the memory. As a result, data loss may occur.

• In this example. the accounts that you use during the data synchronization task are Alibaba Cloud accounts.

• If the Replicate Data Across Alibaba Cloud Accounts parameter of the source database is set to Yes and that of the destination database is set to No, you must use the Alibaba Cloud account to which the destination instance belongs to create the DTS task.

Supported synchronization topologies

• One-way one-to-one synchronization

• One-way one-to-many synchronization

• One-way cascade synchronization

• One-way many-to-one synchronization

For more information about the synchronization topologies that are supported by DTS, see Synchronization topologies.

SQL operations that can be synchronized

Permissions required for database accounts

Limits

RENAME TABLE operations may cause data inconsistency between the source and destination databases. For example, if only Table A is selected as the object to be synchronized and is renamed Table B, Table B cannot be synchronized to the destination database. To prevent this issue, you can select the entire database in which Table A is located as the object to be synchronized when you configure the data synchronization task.

Billing

Preparations

1. Required. Obtain the IDs of the Alibaba Cloud accounts to which the source and destination instances belong and the ID of the Alibaba Cloud account that is used to create the DTS task.

   Note

   If you have obtained the IDs of the required Alibaba Cloud accounts, skip the step.

   1. Use each of the Alibaba Cloud accounts to which the source and destination instances belong and the Alibaba Cloud account that is used to create the DTS task to log on to the Alibaba Cloud Management Console and go to the Security Settings page.

   2. Optional. In the left-side navigation pane, click Security Settings.

   3. View and record the value of the Account ID parameter.

   4. Use each of the Alibaba Cloud accounts to which the source and destination instances belong to perform Steps 2 to 4.

      Note

      If you use the Alibaba Cloud account to which the source instance or destination instance belongs to create the data synchronization task, skip Steps 2 to 4.

2. Create a RAM role.

   Important

   If you grant permissions to a RAM role as a RAM user, an error message about invalid permissions may appear when you configure a DTS task.

   1. Log on to the RAM console by using the Alibaba Cloud account to which the source or destination instance belongs.

   2. In the left-side navigation pane, choose Identities > Roles.

      Important

      Do not choose Identities > Users. Otherwise, DTS cannot access the instance, and an error is reported.

   3. On the Roles page, click Create Role.

   4. On the Create Role page, set the Select Trusted Entity parameter to Alibaba Cloud Account and click Next.

   5. In the Configure Role step, configure parameters for the RAM role.

      Parameter	Description
      RAM Role Name	The name of the RAM role. In this example, ram-for-dts is used as the name of the RAM role that is created by using the Alibaba Cloud account to which the source or destination instance belongs. Note The role name must be 1 to 64 characters in length and can contain letters, digits, and hyphens (-).
      Note	Optional. The description of the RAM role.
      Select Trusted Alibaba Cloud Account	The trusted Alibaba Cloud account. In this example, Other Alibaba Cloud Account is selected and the ID of the Alibaba Cloud account that is used to create the data synchronization task is entered. For more information about how to obtain the ID of an Alibaba Cloud account, see the Preparations section of this topic.

   6. Click OK.

3. Grant permissions to the created RAM role.

   1. Click Input and Attach.

   2. On the Permissions tab, click Precise Permission.

      

   3. In the Precise Permission panel, set the Type parameter to System Policy.

      

   4. In the Policy Name field, enter AliyunDTSRolePolicy.

   5. Click OK.

   6. Click Close.

4. Modify the trust policy.

   1. Optional. On the Roles page, find the created RAM role and click its name.

      

   2. On the details page of the RAM role, click the Trust Policy tab.

      

   3. On the Trust Policy tab, click Edit Trust Policy.

   4. Copy the following code to the code editor:

      {
          "Statement": [
              {
                  "Action": "sts:AssumeRole",
                  "Effect": "Allow",
                  "Principal": {
                      "RAM": [
                          "acs:ram::<Alibaba Cloud account ID>:root"
                      ],
                      "Service": [
                          "<Alibaba Cloud account ID>@dts.aliyuncs.com"
                      ]
                  }
              }
          ],
          "Version": "1"
      }

   5. Replace <Alibaba Cloud account ID> in the code with the ID of the Alibaba Cloud account that is used to create the data synchronization task.

   6. Click Save trust policy document.

Procedure

1. Go to the Data Synchronization Tasks page in the Data Management (DMS) console.

   1. Log on to the DMS console by using the Alibaba Cloud account that is used to create the data synchronization task.

   2. In the top navigation bar, click DTS.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.

   Note

   • Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.

   • You can also go to the Data Synchronization Tasks page of the new DTS console.

2. On the right side of Data Synchronization Tasks, select the region in which the data synchronization instance resides.

   Note

   If you use the new DTS console, you must select the region in which the data synchronization instance resides in the top navigation bar.

3. Click Create Task. In the Create Task wizard, configure the source and destination databases. The following table describes the parameters.

   Warning

   After you select the source and destination instances, we recommend that you read the limits displayed in the upper part of the page. This helps you create and run the data synchronization task.

   Section	Parameter	Description
   N/A	Task Name	The name of the task. DTS automatically assigns a name to the task. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Select a DMS database instance	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the source database. Select MySQL.
   	Access Method	The access method of the source database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the source ApsaraDB RDS for MySQL instance resides. Note You can select different regions for the source and destination ApsaraDB RDS for MySQL instances.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to synchronize data across Alibaba Cloud accounts. In this example, Yes is selected.
   	Alibaba Cloud Account	The ID of the Alibaba Cloud account to which the source instance belongs. For more information about how to obtain the ID of an Alibaba Cloud account, see the Preparations section of this topic.
   	RAM Role Name	The name of the RAM role that is configured for the Alibaba Cloud account to which the source ApsaraDB RDS instance belongs. In this example, ram-for-dts that you create in the preparations is used.
   	RDS Instance ID	The ID of the source ApsaraDB RDS for MySQL instance. Note If an alert message is displayed when you select an ApsaraDB RDS instance ID, modify the parameter settings as prompted. For more information about alert messages, see the FAQ section of this topic.
   	Database Account	The database account of the source ApsaraDB RDS for MySQL instance.
   	Database Password	The password of 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. In this example, Non-encrypted is selected. Note If you want to select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data synchronization task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance.
   Destination Database	Select a DMS database instance	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the destination database. Select MySQL.
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination ApsaraDB RDS for MySQL instance resides. Note You can select different regions for the source and destination ApsaraDB RDS for MySQL instances.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to synchronize data across Alibaba Cloud accounts. In this example, Yes is selected.
   	Alibaba Cloud Account	The ID of the Alibaba Cloud account to which the destination instance belongs. For more information about how to obtain the ID of an Alibaba Cloud account, see the Preparations section of this topic.
   	RAM Role Name	The name of the RAM role that is configured for the Alibaba Cloud account to which the destination instance belongs. In this example, the ram-for-dts role that you create in the preparations is used. Important Do not enter the default role AliyunDTSDefaultRole of DTS.
   	RDS Instance ID	The ID of the destination ApsaraDB RDS for MySQL instance. Note If an alert message is displayed when you select an ApsaraDB RDS instance ID, modify the parameter settings as prompted. For more information about alert messages, see the FAQ section of this topic.
   	Database Account	The database account of the destination ApsaraDB RDS for MySQL instance.
   	Database Password	The password of 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. In this example, Non-encrypted is selected. Note If you want to select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data synchronization task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance.

4. In the lower part of the page, click Test Connectivity and Proceed.

   If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must make sure that the ECS instance can access the database. If the database is deployed on multiple ECS instances, you must manually add the CIDR blocks of DTS servers to the security group rules of each ECS instance. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information, see Add the CIDR blocks of DTS servers.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

5. Configure the objects to be synchronized and advanced settings.

   Parameter	Description
   Synchronization Types	The synchronization types. By default, Incremental Data Synchronization is selected. We recommend that you also select Schema Synchronization and Full Data Synchronization. After the precheck is complete, DTS synchronizes the historical data of selected objects from the source database to the destination database. The historical data serves as the basis for subsequent incremental synchronization.
   Method to Migrate Triggers in Source Database	The method used to synchronize triggers from the source database. You can select a synchronization method based on your business requirements. If no triggers are to be synchronized, you do not need to set this parameter. For more information, see Synchronize or migrate triggers from the source database. Note This parameter is available only if you select Schema Synchronization for the Synchronization Types parameter.
   Enable Migration Assessment	Specifies whether to enable synchronization assessment. Synchronization assessment aims to check whether the schemas of the source and destination databases, such as the length of indexes, stored procedures, and dependent tables, meet the requirements. You can select Yes or No based on your business requirements. If you select Yes, the precheck may take more time. You can view the assessment results during the precheck. The assessment results do not affect the precheck results. Note This parameter is available only if you select Schema Synchronization for the Synchronization Types parameter. If you select Yes, the precheck may take more time. You can view the assessment results during the precheck. The assessment results do not affect the precheck results.Assessment Result
   Synchronization Topology	The synchronization topology. In this example, One-way Synchronization is selected.
   Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that have 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 synchronization task cannot be started. Note If the source and destination databases contain identical table 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 synchronized 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 in the destination database has the same primary key value or unique key value as a data record in the source database: During full data synchronization, DTS does not synchronize the data record to the destination database. The existing data record in the destination database is retained. During incremental data synchronization, DTS synchronizes 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, data may fail to be initialized. In this case, only some columns are synchronized, or the data synchronization 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 ensure that the capitalization of object names is consistent with that in 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 and click the icon to move the objects to the Selected Objects section. Note You can select columns, tables, or databases as the objects to be synchronized. If you select tables or columns as the objects to be synchronized, DTS does not synchronize other objects such as views, triggers, and stored procedures to the destination database.
   Selected Objects	To rename an object that you want to synchronize to the destination instance, right-click the object in the Selected Objects section. For more information, see the Map the name of a single object section of the "Map object names" topic. To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see the Map multiple object names at a time section of the "Map object names" topic. Note To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to synchronize. For more information about the SQL statements that can be synchronized, see the SQL operations that can be synchronized section of this topic. To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Set filter conditions.

6. Click Next: Advanced Settings to configure advanced settings.

   • Data Verification Settings

     For more information about how to configure the data verification feature, see Enable data verification.

   • Advanced Settings

     Parameter or setting	Description
     Select the dedicated cluster used to schedule the task	By default, DTS schedules tasks to shared clusters. You do not need to configure this parameter. You can purchase a dedicated cluster of specific specifications to run DTS data synchronization tasks. For more information, see What is a DTS dedicated cluster.
     Set Alerts	Specifies whether to configure alerting for the data synchronization task. If the task fails or the synchronization latency exceeds the specified threshold, alert contacts will receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert contacts. For more information, see Configure monitoring and alerting.
     Copy the temporary table of the Online DDL tool that is generated in the source table to the destination database.	If you use DMS or the gh-ost tool to perform online DDL operations on the source database, you can specify whether to synchronize the data of temporary tables generated by online DDL operations. Important You cannot use tools such as pt-online-schema-change to perform online DDL operations on the source database. Otherwise, the DTS task fails. Yes: DTS synchronizes the data of temporary tables generated by online DDL operations. Note If online DDL operations generate a large amount of data, the data synchronization task may take an extended period of time to complete. No, Adapt to DMS Online DDL: DTS does not synchronize the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using DMS are synchronized. Note If you select this option, the tables in the destination database may be locked. No, Adapt to gh-ost: DTS does not synchronize the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using the gh-ost tool are synchronized. You can use the default or custom regular expressions to filter out the shadow tables of the gh-ost tool and tables that are not required. Note If you select this option, the tables in the destination database may be locked.
     Whether to Migrate Accounts	Specifies whether to synchronize the account information of the source database. You can configure this parameter based on your business requirements. If you select Yes, you must select the accounts that you want to synchronize and check the permissions of the source and destination database accounts used in the data synchronization task. Important The account of the source database must have the SELECT permission on the mysql.user, mysql.db, mysql.columns_priv, and mysql.tables_priv metadata tables. The account of the destination database must have the CREATE USER and GRANT OPTION permissions on the destination database. The accounts that already exist in the destination database and the system accounts of the source database, such as root, mysql.infoschema, mysql.session, and mysql.sys, cannot be synchronized.
     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 synchronization task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set this parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Note If you specify different retry time ranges for multiple data synchronization tasks that have the same source or destination database, the shortest retry time range 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 your earliest opportunity after the source and destination instances are released.
     The wait time before a retry when other issues occur in the source and destination databases.	The retry time range for other issues. For example, if the DDL or DML operations fail to be performed after the data synchronization task is started, DTS immediately retries the operations within the time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set this parameter to a value greater than 10. If the failed operations are successfully performed within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Important The value of the The wait time before a retry when other issues occur in the source and destination databases. parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
     Enable Throttling for Full Data Migration	During full data synchronization, DTS uses the read and write resources of the source and destination databases. This may increase the load on the database servers. You can 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 for full data synchronization tasks to reduce the load on the destination database server. Note This parameter is displayed only if Full Data Synchronization is selected for the Synchronization Types parameter.
     Enable Throttling for Incremental Data Synchronization	Specifies whether to enable throttling for incremental data synchronization. You can enable throttling for incremental data synchronization based on your business requirements. To configure throttling, you must configure the RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s) parameters. This reduces the load on the destination database server.
     Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is selected.
     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.
     Whether to delete SQL operations on heartbeat tables of forward and reverse tasks	Specifies whether to write SQL operations on heartbeat tables to the source database while the DTS instance is running. Yes: does not write SQL operations on heartbeat tables. In this case, a latency of the DTS instance may be displayed. No: writes SQL operations on heartbeat tables. In this case, specific features such as physical backup and cloning of the source database may be affected.

7. 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 synchronization task, DTS performs a precheck. You can start the data synchronization 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 issue. Then, run a precheck again.

     • If an 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.

8. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

9. On the Purchase Instance page, configure the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.

   Section	Parameter	Description
   New Instance Class	Billing Method	Subscription: You pay for your subscription when you create an instance. The subscription billing method is more cost-effective than the pay-as-you-go billing method for long-term use. Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. We recommend that you select the pay-as-you-go billing method for short-term use. If you no longer require a pay-as-you-go instance, you can release the instance to reduce costs.
   	Resource Group	The resource group to which the instance belongs. Default value: default resource group. For more information, see What is Resource Management?
   	Instance Class	DTS provides various synchronization specifications that provide different performance. The synchronization speed varies based on the synchronization specifications that you select. You can select a synchronization specification based on your business requirements. For more information, see Specifications of data synchronization instances.
   	Duration	If you select the subscription billing method, set the subscription duration and the number of instances that you want to create. The subscription duration can be one to nine months, one year, two years, three years, or five years. Note This parameter is displayed only if you select the subscription billing method.Subscription

10. Read and select the Data Transmission Service (Pay-as-you-go) Service Terms.

11. Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.

FAQ

• What Alibaba Cloud accounts do I use in different stages of a cross-account DTS task?

  In a cross-account DTS task, the use of each Alibaba Cloud account is related to the database of the Alibaba Cloud account. Take note of the following items when you decide to use an Alibaba Cloud account:

  Note

  • The accounts that you use during the DTS task are Alibaba Cloud accounts.

  • If a database to be used during the task does not belong to the Alibaba Cloud account that you use to create the DTS task, set the Replicate Data Across Alibaba Cloud Accounts parameter of the database to Yes.

  • The Replicate Data Across Alibaba Cloud Accounts parameter is available only if you select MySQL or ClickHouse for the Database Type parameter in the Destination Database section.

  The following table describes how to decide the Alibaba Cloud accounts that you need to use in different stages of the cross-account DTS task. You must decide the across-account database that you want to use first. Find the row that meets your business requirements based on the Across-account database column. Then, you can view the Alibaba Cloud accounts that you need to use in different stages of the cross-account DTS task.

  Across-account database	Alibaba Cloud account that is used to log on to the RAM console	Alibaba Cloud account that is specified in the trust policy	Alibaba Cloud Account that is used to create the DTS task	Alibaba Cloud account that is configured for the Alibaba Cloud Account parameter
  Source database	Alibaba Cloud account to which the source database belongs	Alibaba Cloud account to which the destination database belongs	Alibaba Cloud account to which the destination database belongs	Set the Alibaba Cloud Account parameter in the Source Database section to the Alibaba Cloud account to which the source database belongs.
  Destination database	Alibaba Cloud account to which the destination database belongs	Alibaba Cloud account to which the source database belongs	Alibaba Cloud account to which the source database belongs	Set the Alibaba Cloud Account parameter in the Destination Database section to the Alibaba Cloud account to which the destination database belongs.
  Source and destination databases	Each of the Alibaba Cloud accounts to which the source and destination database belong	Specific Alibaba Cloud account	Specific Alibaba Cloud account	Set the Alibaba Cloud Account parameter in the Source Database section to the Alibaba Cloud account to which the source database belongs. Set the Alibaba Cloud Account parameter in the Destination Database section to the Alibaba Cloud account to which the destination database belongs.

• How do I handle the errors that occur when I configure a cross-account DTS task?

  The following table shows the common error messages that appear when you configure a cross-account DTS task and provides the corresponding solutions.

  Error message	Solution
  	The value of the Alibaba Cloud Account parameter is invalid. Check whether you enter a valid ID of the Alibaba Cloud account to which the source or destination instance belongs. For more information, see the Preparations section of this topic.
  	These errors may occur due to the following reasons: The value of the RAM Role Name parameter is invalid. Check whether you enter a valid RAM role name of the Alibaba Cloud account to which the source or destination instance belongs. The required permissions are not granted to the RAM role. Use the Alibaba Cloud account to which the source or destination instance belongs to grant permissions. Note For more information, see the Preparations section of this topic.
  	These errors may occur due to the following reasons: The value of the RAM Role Name parameter is invalid. Check whether you enter a valid RAM role name of the Alibaba Cloud account to which the source or destination instance belongs. The required permissions are not granted to the RAM role. Check whether you have granted the required permissions to the RAM role. The trust policy of the RAM role is not modified. Check whether you have modified the trust policy for the RAM role. Note For more information, see the Preparations section of this topic.
  	The RAM role that you specify in the RAM Role Name parameter is not granted the required permissions. To grant the required permissions to the RAM role, go to the details page of the RAM role. On the Permissions tab, click Precise Permission and specify the policy in the Precise Permission panel. Then, create the task again. For example, you must grant the required permissions to the RAM role of the Alibaba Cloud account to which the source instance belongs. For information about how to grant permissions to a RAM role, see the "Grant permissions to an existing RAM role" section of the Configure RAM authorization for cross-account DTS tasks topic.
  	The value of the RAM Role Name parameter is invalid. Enter the RAM role that you create during preparations instead of the default role AliyunDTSDefaultRole of DTS.