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    Data Transmission Service:Migrate data from a self-managed MongoDB database (replica set architecture) to an ApsaraDB for MongoDB instance (replica set or sharded cluster architecture)

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    Data Transmission Service:Migrate data from a self-managed MongoDB database (replica set architecture) to an ApsaraDB for MongoDB instance (replica set or sharded cluster architecture)

    Last Updated:Dec 05, 2025

    This topic describes how to use Data Transmission Service (DTS) to migrate data from a self-managed MongoDB database with a replica set architecture to an ApsaraDB for MongoDB instance with a replica set or sharded cluster architecture.

    Prerequisites

    • A destination ApsaraDB for MongoDB instance that uses a replica set or sharded cluster architecture is created. For more information, see Create a replica set instance and Create a sharded cluster instance.

      Important

      • We recommend that the storage space of the destination ApsaraDB for MongoDB instance be at least 10% larger than the storage space used by the source self-managed MongoDB instance.

      • For more information about the supported versions, see Overview of data migration solutions.

    • If the destination ApsaraDB for MongoDB instance uses a sharded cluster architecture, you must create the databases and collections to be sharded, configure data sharding, enable the balancer, and perform presharding in the destination ApsaraDB for MongoDB instance as needed. For more information, see Configure data sharding to maximize shard performance and Handle uneven data distribution in a sharded cluster MongoDB instance.

      Note

      Configuring data sharding prevents all data from being migrated to a single shard, which would otherwise affect cluster performance. Enabling the balancer and performing presharding helps prevent data skew.

    Notes

    Type

    Description

    Source database limits

    • Bandwidth requirements: The server on which the source database is deployed must have sufficient outbound bandwidth. Otherwise, the data migration speed decreases.

    • If the source database is an Azure Cosmos DB for MongoDB cluster or an Amazon DocumentDB elastic cluster, only full data migration is supported.

    • Requirements for migration objects:

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

      • If you select collections as the objects to be migrated and you need to edit collections in the destination database, such as renaming collections, up to 1,000 collections can be migrated in a single data migration task. If you run a task to migrate more than 1,000 collections, a request error occurs. In this case, we recommend that you configure multiple tasks to migrate the collections in batches or configure a task to migrate the entire database.

      • The size of a single data entry in the source database cannot exceed 16 MB. Otherwise, the data migration task fails.

      • If the source database contains TTL indexes, data inconsistency may occur between the source and destination databases after the migration.

    • To perform incremental data migration, you must make sure that the following requirements are met:

      The oplog feature is enabled for the source database and operation logs of the source database are retained for at least seven days. Alternatively, change streams are enabled for the source database and DTS can use change streams to subscribe to data changes in the source database within the last seven days. Otherwise, DTS may fail to obtain the operation logs and the data migration task may fail. In exceptional circumstances, data inconsistency or loss may occur. The service level agreement (SLA) of DTS does not cover these issues.

      Important

      • We recommend that you use the oplog feature to obtain data changes in the source database.

      • You can use change streams to obtain data changes in the source database only if the source database runs MongoDB V4.0 or later.

      • If the source database is an inelastic Amazon DocumentDB cluster, you must enable change streams for the database and set the Migration Method parameter to ChangeStream and the Architecture parameter to Sharded Cluster when you configure the data migration task.

    • Limits on operations to be performed on the source database:

      • During schema migration and full data migration, do not perform schema change on databases or collections, including the update of the array type. Otherwise, the data migration task fails, or data inconsistency between the source and destination databases may occur.

      • If you perform only full data migration, do not write data to the source database during data migration. Otherwise, data inconsistency between the source and destination databases occurs. To ensure data consistency, we recommend that you select Schema Migration, Full Data Migration, and Incremental Data Migration as the migration types.

    • If you perform a primary/secondary switchover on the source database when the data migration task is running, the task fails.

    • DTS calculates migration latency based on the timestamp of the latest migrated data in the destination database and the current timestamp in the source database. If no update operation is performed on the source database for an extended period of time, the migration latency may be inaccurate. If the latency of the migration task is excessively high, you can perform an update operation on the source database to update the latency.

    Other limits

    • If the destination database is a sharded cluster database, take note of the following limits:

      • Orphaned documents must be deleted. Otherwise, the migration performance is compromised. During data migration, if a _id conflict exists in the documents of the source and destination databases, data inconsistency may occur, or the data migration task may fail.

      • Before you start the data migration task, you must add shard keys to the data to be migrated in the source database. If you cannot add shard keys to the data in the source database, you can migrate data from a MongoDB database without shard keys. For more information, see Migrate data from a MongoDB instance without a sharding key to a MongoDB sharded cluster instance.

      • During the data migration, if you execute the INSERT statement to insert data into the data to be migrated, the data to be migrated must contain shard keys. If you execute the UPDATE statement to modify the data to be migrated, you cannot modify shard keys.

    • If the destination database is a replica set instance, take note of the following limits:

      • If the destination database is connected over Express Connect, VPN Gateway, or Smart Access Gateway, Public IP Address, or Cloud Enterprise NetworkCEN, set the Domain Name or IP and Port Number to the IP address and the port number of primary node, or configure a high-availability endpoint. For more information about high-availability endpoints, see Create a DTS task in which the source or destination database is a high-availability MongoDB database.

      • If the destination database is connected over Self-managed Database on ECS, set the Port Number to the port number of primary node.

    • DTS cannot connect MongoDB database over a SRV endpoint.

    • To ensure compatibility, the version of the destination MongoDB database must be the same as or later than the version of the source MongoDB database. If the version of the destination database is earlier than the version of the source database, database compatibility issues may occur.

    • DTS cannot migrate data from the admin, config, or local database.

    • If a collection of the destination database has a unique index or the capped attribute of a collection of the destination database is true, the collection supports only single-thread data writing and does not support concurrent replay during incremental data migration. This may increase migration latency.

    • Transaction information is not retained. When transactions are migrated to the destination database, the transactions are converted into a single record.

    • If a primary key or a unique key conflict occurs during which DTS writes data to the destination collection, DTS skips the statements used to write data and retain the existing data in the destination collection.

    • Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads on the database servers.

    • During full data migration, concurrent INSERT operations cause fragmentation in the collections of the destination database. After full data migration is complete, the storage space for collections of the destination database is larger than that of the source database.

    • You must make sure that the precision settings for columns of the FLOAT or DOUBLE data type meet your business requirements. DTS uses the ROUND(COLUMN,PRECISION) function to retrieve values from columns of the FLOAT or DOUBLE data type. If you do not specify a precision, DTS sets the precision for the FLOAT data type to 38 digits and the precision for the DOUBLE data type to 308 digits.

    • DTS attempts to resume a data migration task that failed within the last seven days. Before you switch workloads to the destination cluster, you must stop or release the failed tasks. You can also execute the REVOKE statement to revoke the write permissions from the accounts that are used by DTS to access the destination database. Otherwise, the data in the source database overwrites the data in the destination database after the data migration task is resumed.

    • The data is concurrently written to the destination database. Therefore, the storage space occupied in the destination database is 5% to 10% larger than the size of the data in the source database.

    • You must use the db.$table_name.aggregate([{ $count:"myCount"}]) syntax to query the return value of a count operation on the destination MongoDB database.

    • Make sure that the destination MongoDB database does not have the same primary key as the source database. The default primary key is _id. Otherwise, data may be lost. If the data in the destination database has the same primary key as that in the source database, clear the related data in the destination database without interrupting the services of DTS. For example, if the same primary key is _id, you can delete the data in the destination database that has the same _id as the source database.

    • If an instance fails, DTS helpdesk will try to recover the instance within 8 hours. During the recovery process, operations such as restarting the instance and adjusting parameters may be performed.

      Note

      When parameters are adjusted, only the parameters of the DTS instance are modified. The parameters of the database are not modified. The parameters that may be modified include but are not limited to those described in Modify instance parameters.

    • If you migrate data to another MongoDB database (sharded cluster architecture), make sure that your business behavior meets the requirements of the ApsaraDB for MongoDB sharded cluster.

    Special cases

    When the source database is a self-managed MongoDB database:

    • If a primary/secondary failover occurs in the source database during migration, the migration task fails.

    • DTS calculates migration latency by comparing the timestamp of the latest migrated data in the destination database with the current timestamp. If the source database has not been updated for a long time, the displayed latency may be inaccurate. If the task shows a high latency, perform an update operation in the source database to refresh the latency information.

    Note

    If you select an entire database as the migration object, you can also create a heartbeat table. The heartbeat table is updated or receives data every second.

    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.

    Migration types

    Migration type

    Description

    Schema migration

    DTS migrates the schemas of the migration objects from the source self-managed MongoDB database to the destination ApsaraDB for MongoDB instance.

    Note

    DTS can migrate the schemas of the following objects: DATABASE, COLLECTION, and INDEX.

    Full migration

    DTS migrates all historical data of the migration objects from the source self-managed MongoDB database to the destination ApsaraDB for MongoDB instance.

    Note

    DTS can migrate the data of DATABASE and COLLECTION objects.

    Incremental migration

    After full migration, DTS migrates incremental updates from the source self-managed MongoDB database to the destination ApsaraDB for MongoDB instance.

    Use oplog

    A DTS task does not migrate incremental data from databases that are created after the task starts to run. DTS migrates incremental data generated by the following operations:

    • CREATE COLLECTION and CREATE INDEX

    • DROP DATABASE, DROP COLLECTION, and DROP INDEX

    • RENAME COLLECTION

    • The operations that are performed to insert, update, and delete documents in a collection.

      Note

      When you migrate the incremental data of updated documents, migrate only updates from $set.

    Use change streams

    DTS migrates incremental data generated by the following operations:

    • DROP DATABASE and DROP COLLECTION

    • RENAME COLLECTION

    • The operations that are performed to insert, update, and delete documents in a collection

    Note

    When you migrate the incremental data of updated documents, migrate only updates from $set .

    Permissions required for database accounts

    Database

    Schema migration

    Full migration

    Incremental migration

    Source self-managed MongoDB

    The read permission on the database to be migrated and the config database.

    The read permission on the database to be migrated, the admin database, and the local database.

    Destination ApsaraDB for MongoDB

    The dbAdminAnyDatabase permission, the readWrite permission on the destination database, and the read permission on the local database.

    Procedure

    1. Use one of the following methods to go to the Data Migration page and select the region in which the data migration instance resides.

      DTS console

      1. Log on to the DTS console.

      2. In the left-side navigation pane, click Data Migration.

      3. In the upper-left corner of the page, select the region in which the data migration instance resides.

      DMS console

      Note

      The actual operation 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.

      1. Log on to the DMS console.

      2. In the top navigation bar, move the pointer over Data + AI > DTS (DTS) > Data Migration.

      3. From the drop-down list to the right of Data Migration Tasks, select the region in which the data synchronization instance resides.

    2. Click Create Task to go to the task configuration page.

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

      Warning

      After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

      Category

      Configuration

      Description

      N/A

      Task Name

      The name of the DTS task. DTS automatically generates a task name. We recommend that you specify an informative name that makes it easy to identify the task. You do not need to specify a unique task name.

      Source Database

      Select Existing Connection

      • If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections.

        Note

        In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list.

      • If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.

      Database Type

      Select MongoDB.

      Access Method

      Select a connection type based on the deployment location of the source database. This topic uses Public IP Address as an example.

      Note

      If you select another connection type for the self-managed database, you must also perform the required preparations.

      Instance Region

      Select the region where the self-managed MongoDB database resides.

      Note

      If the region where the self-managed MongoDB database resides is not an option, you can select the region that is geographically closest to the database.

      Architecture

      Select Replica Set.

      Migration Method

      The method used to migrate incremental data from the source database. Select a method based on your business requirements. Valid values:

      • Oplog (recommended):

        This option is available if the oplog feature is enabled for the source database.

        Note

        By default, the oplog feature is enabled for both self-managed MongoDB databases and ApsaraDB for MongoDB instances. This feature allows you to migrate incremental data at a low latency because of a fast log pulling speed. Therefore, we recommended that you select Oplog for the Migration Method parameter.

      • ChangeStream: This option is available if change streams are enabled for the source database. For more information, see Change Streams.

        Note

        • If the source database is an inelastic Amazon DocumentDB cluster, you can set the Migration Method parameter only to ChangeStream.

        • If you select Sharded Cluster for the Architecture parameter, you do not need to configure the Shard account and Shard password parameters.

      Endpoint Type

      Select Standalone or Multi-node as needed.

      Note

      This parameter is available only if you set the connection type for the self-managed MongoDB database to Express Connect, VPN Gateway, or Smart Access Gateway, Public IP Address, or Cloud Enterprise Network (CEN).

      Domain Name or IP

      Enter the domain name or IP address of the self-managed MongoDB database. In this example, a public IP address is entered.

      Note

      This parameter is available only if you set Endpoint Type to Standalone.

      Port Number

      Enter the service port of the self-managed MongoDB database.

      Note

      This parameter is available only if you set Endpoint Type to Standalone.

      Endpoint

      Enter the endpoint of the self-managed MongoDB database.

      Note

      • This parameter is available only if you set Endpoint Type to Multi-node.

      • The format is <IP>:<Port>. <IP> is a domain name or IP address. We recommend that you use a domain name that can be resolved over the Internet.

      • You can press the Enter key to separate multiple endpoints.

      Authentication Database

      Enter the name of the database to which the database account of the self-managed MongoDB database belongs. The default value is admin.

      Database Account

      Enter the account of the corresponding Mongos node in the self-managed MongoDB database. For information about the required permissions, see Permissions required for database accounts.

      Note

      If you set Access Method of the self-managed MongoDB database to Self-managed Database on ECS or Database Gateway, enter the account of the shard node.

      Database Password

      The password that is used to access the database instance.

      Encryption

      Specifies whether to encrypt the connection to the source database. You can select Non-encrypted, SSL-encrypted, or Mongo Atlas SSL based on your business requirements. The options available for the Encryption parameter are determined by the values selected for the Access Method and Architecture parameters. The options displayed in the DTS console prevail.

      Note

      • If the Architecture parameter is set to Sharded Cluster, and the Migration Method parameter is set to Oplog for the ApsaraDB for MongoDB database, the Encryption parameter SSL-encrypted is unavailable.

      • If the source database is a self-managed MongoDB database that uses the Replica Set architecture, the Access Method parameter is not set to Alibaba Cloud Instance, and the Encryption parameter is set to SSL-encrypted, you can upload a certification authority (CA) certificate to verify the connection to the source database.

      Destination Database

      Select Existing Connection

      • If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections.

        Note

        In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list.

      • If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.

      Database Type

      Select MongoDB.

      Access Method

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the destination ApsaraDB for MongoDB instance resides.

      Replicate Data Across Alibaba Cloud Accounts

      In this example, a database instance of the current Alibaba Cloud account is used. Select No.

      Architecture

      Select the architecture type of the destination ApsaraDB for MongoDB instance.

      Instance ID

      Select the ID of the destination ApsaraDB for MongoDB instance.

      Authentication Database

      Enter the name of the database to which the database account of the destination ApsaraDB for MongoDB instance belongs. The default value is admin.

      Database Name

      Enter the name of the database to which the migration objects belong in the destination ApsaraDB for MongoDB instance.

      Database Account

      Enter the database account of the destination ApsaraDB for MongoDB instance. For information about the required permissions, see Permissions required for database accounts.

      Database Password

      The password that is used to access the database instance.

      Encryption

      Specifies whether to encrypt the connection to the destination database. You can select Non-encrypted, SSL-encrypted, or Mongo Atlas SSL based on your business requirements. The options available for the Encryption parameter are determined by the values selected for the Access Method and Architecture parameters. The options displayed in the DTS console prevail.

      Note

      • If the destination database is an ApsaraDB for MongoDB instance and the Architecture parameter is set to Sharded Cluster, the Encryption parameter SSL-encrypted is unavailable.

      • If the destination database is a self-managed MongoDB database that uses the Replica Set architecture, the Access Method parameter is not set to Alibaba Cloud Instance, and the Encryption parameter is set to SSL-encrypted, you can upload a CA certificate to verify the connection to the destination database.

    4. In the lower part of the page, click Test Connectivity and Proceed, and then click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.

      Note

      Make sure that the CIDR blocks of DTS servers can be automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add DTS server IP addresses to a whitelist.

    5. Configure the objects to be migrated.

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

        Configuration

        Description

        Migration Types

        • To perform only full data migration, select Schema Migration and Full Data Migration.

        • To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.

        Note

        • If you do not select Schema Migration, make sure a database and a table are created in the destination database to receive data and the object name mapping feature is enabled in Selected Objects.

        • If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.

        Processing Mode of Conflicting Tables

        • Precheck and Report Errors: checks whether the destination database contains collections that have the same names as collections in the source database. If the source and destination databases do not contain collections that have identical names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started.

          Note

          If the source and destination databases contain collections with identical names and the collections in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the collections that are migrated to the destination database. For more information, see Map object names.

        • Ignore Errors and Proceed: skips the precheck for identical collection names in the source and destination databases.

          Warning

          If you select Ignore Errors and Proceed, data consistency is not ensured and your business may be exposed to potential risks.

          • DTS does not migrate data records that have the same primary keys as data records in the destination database.

          • Data may fail to be initialized, only specific columns are migrated, or the data migration task fails.

        Capitalization of Object Names in Destination Instance

        The capitalization of database names and collection names in the destination instance. By default, DTS default policy is selected. You can select another option to ensure that the capitalization of object names is the same as that of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.

        Source Objects

        Select one or more objects from the Source Objects section. Click the 向右小箭头 icon to add the objects to the Selected Objects section.

        Note

        You can select databases or collections as migration objects.

        Selected Objects

        • To specify the name of an object to be migrated in the destination instance or specify the object to receive data in the destination instance, right-click the object in the Selected Objects section. For more information, see Map object names.

        • To remove one or more objects that are selected for migration, click the objects in the Selected Objects section and then click the image icon to move the objects to the Source Objects section.

        Note

        • To select the incremental migration mode for databases and collections, right-click objects to be migrated in the Selected Objects section and then select the mode in the dialog box that appears.

        • To specify WHERE conditions to filter data, right-click a table in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Specify filter conditions. You can specify WHERE conditions during full migration but not incremental migration.

        • If you use the object name mapping feature to specify databases or collections for receiving data, other objects depending on the specified objects may fail to be migrated.

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

        Configuration

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS schedules the task to a shared cluster. You do not need to make a selection. You can purchase a dedicated cluster with a specific specification to run DTS migration tasks. For more information, see What is a DTS dedicated cluster?

        Retry Time for Failed Connections

        The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the retry time range. Valid values: 10 to 1,440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails.

        Note

        • If you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later takes precedence.

        • When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at the earliest opportunity after the source database and destination instance are released.

        Retry Time for Other Issues

        The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails.

        Important

        The value of the Retry Time for Other Issues parameter must be smaller than the value of the Retry Time for Failed Connections parameter.

        Enable Throttling for Full Data Migration

        Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server.

        Note

        You can configure this parameter only if you select Full Data Migration for the Migration Types parameter.

        Only one data type for primary key _id in a table of the data to be synchronized

        Specifies whether the data type of the primary key _id is unique in a collection to be migrated.

        Important

        • Enable this parameter based on your business requirements. Otherwise, data loss may occur.

        • This parameter is required only if you select Full Data Migration for the Migration Types parameter.

        Valid values:

        • Yes: The data type is unique. During full migration, DTS does not scan the data type of the primary key in source database. DTS only migrates a data type of the primary key in a collection to be migrated.

        • No: The data type is not unique. During full migration, DTS scans the data types of the primary key in source database and migrates the data of all data types.

        Enable Throttling for Incremental Data Migration

        Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server.

        Note

        You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.

        Environment Tag

        You can select an environment tag to identify the instance based on your 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:

        Monitoring and Alerting

        Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values:

      3. Click Next Step: Data Verification to configure the data verification task.

        For more information about how to use the data verification feature, see Configure a data verification task.

    6. Save the task settings and run a precheck.

      • To view the parameters to be specified when you call the relevant API operation to configure the DTS task, move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters.

      • If you do not need to view or have viewed the parameters, click Next: Save Task Settings and Precheck in the lower part of the page.

      Note

      • Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.

      • If the task fails to pass the precheck, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.

      • If an alert is triggered for an item during the precheck:

        • If an alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.

        • If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur, and your business may be exposed to potential risks.

    7. Purchase the instance.

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

      2. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

        Section

        Parameter

        Description

        New Instance Class

        Resource Group

        The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?

        Instance Class

        DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Instance classes of data migration instances.

      3. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

      4. Click Buy and Start. In the message that appears, click OK.

        You can view the progress of the task on the Data Migration page.

        Note

        • If a data migration task cannot be used to migrate incremental data, the task automatically stops. The Completed is displayed in the Status section.

        • If a data migration task can be used to migrate incremental data, the task does not automatically stop. The incremental data migration task never stops or completes. The Running is displayed in the Status section.