All Products
Search

This Product

    Data Transmission Service:Migrate MongoDB (without a sharding key) to MongoDB (sharded cluster architecture)

    Document Center

    Data Transmission Service:Migrate MongoDB (without a sharding key) to MongoDB (sharded cluster architecture)

    Last Updated:Aug 22, 2025

    Data Transmission Service (DTS) lets you migrate data from a source MongoDB database that does not have a sharding key to a destination MongoDB database that uses a sharded cluster architecture. During the migration, you can specify a default value for the sharding key. This topic uses an ApsaraDB for MongoDB instance with a replica set architecture as the source and an ApsaraDB for MongoDB instance with a sharded cluster architecture as the destination to demonstrate the migration steps.

    Prerequisites

    • Create a destination ApsaraDB for MongoDB instance with a sharded cluster architecture. For more information, see Create a sharded cluster instance.

      Note

      • If the source is an ApsaraDB for MongoDB instance with a sharded cluster architecture, you must request an endpoint for the shard nodes. Ensure that the database accounts and passwords for each shard are the same. For more information, see Request an endpoint for a shard node.

      • For supported versions, see Migration solutions.

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

    • If required, create databases and collections that require sharding in the destination ApsaraDB for MongoDB instance. Configure data sharding, enable the balancer, and perform pre-sharding. For more information, see Configure data sharding to maximize shard performance and How do I handle uneven data distribution in a MongoDB sharded cluster?.

      Note

      Configuring data sharding prevents all data from being migrated to a single shard, which ensures that you can take full advantage of the cluster performance. Enabling the balancer and pre-sharding helps avoid data skew.

    Notes

    Type

    Description

    Source database limits

    • Bandwidth requirements: The server of the source database must have sufficient outbound bandwidth. Otherwise, the migration speed is affected.

    • Collections to be migrated must have a primary key or a UNIQUE constraint. The fields in the constraint must be unique. Otherwise, duplicate data may exist in the destination database.

    • If you migrate objects at the collection level and need to edit them, such as mapping collection names, a single migration task supports a maximum of 1,000 collections. If this limit is exceeded, an error is reported after you submit the task. In this case, split the collections into multiple migration tasks, 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 MongoDB instance is a sharded cluster, the number of Mongos nodes cannot exceed 10.

    • If the source instance is a self-managed MongoDB database with a sharded cluster architecture:

      • The following Access Method options are supported: Public IP Address, Express Connect, VPN Gateway, or Smart Access Gateway, and Cloud Enterprise Network (CEN).

      • If the MongoDB version is 8.0 or later and Migration Method is set to Oplog, you must grant the directShardOperations permission to the shard account used for the migration task. You can run the db.adminCommand({ grantRolesToUser: "username", roles: [{ role: "directShardOperations", db: "admin"}]}) command to grant the permission.

        Note

        In the command, replace username with the shard account used for the migration task.

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

    • 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.

    • Operational limits 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 the source MongoDB instance is deployed in a sharded cluster architecture, do not run commands such as shardCollection, reshardCollection, unshardCollection, moveCollection, and movePrimary to change data distribution for the object to be migrated in the source database when the data migration instance is running. Otherwise, data inconsistency may occur.

      • If you perform only full data migration, do not write new data to the source instance. Otherwise, data becomes inconsistent between the source and destination databases. To ensure real-time data consistency, select Schema Migration, Full Data Migration, and Incremental Data Migration.

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

    • Ensure that no orphaned documents exist in the MongoDB instance with a sharded cluster architecture. Otherwise, data inconsistency or task failure may occur. For more information, see Orphaned Documents and How do I clean up orphaned documents in a MongoDB sharded cluster?.

    • If the source database is a MongoDB instance with a sharded cluster architecture and the balancer is balancing data, instance latency may occur.

    Other limits

    • You cannot set default values for the sharding keys of new collections that are added to the source database during migration.

    • DTS does not support connecting to a MongoDB database using an SRV address.

    • If the source is a non-sharded cluster and the destination is an Alibaba Cloud MongoDB instance with a sharded cluster architecture, the task proceeds to the Configure Database and Table Fields step.

    • If the version of the destination MongoDB instance (sharded cluster architecture) is earlier than 4.4, the default ShardKey value set in the Configure Database and Table Fields step takes effect. DTS fills the original data with the default value and writes the data to the destination. If the destination MongoDB instance (sharded cluster architecture) is version 4.4 or later, the default value set in the Configure Database and Table Fields step does not take effect. DTS writes the original data to the destination by default.

    • We recommend that you keep the database versions of the source and destination MongoDB instances the same, or migrate from an earlier version to a later version to ensure compatibility. If you migrate from a later version to an earlier version, database compatibility issues may occur.

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

    • Transaction information is not retained. When transactions in the source database are migrated to the destination database, they are converted into individual records.

    • When DTS writes data to a destination collection, if a primary key or unique key conflict occurs, DTS skips the corresponding write statement and retains the existing data in the destination collection.

    • If the source database is a MongoDB version earlier than 3.6 and the destination database is a MongoDB version 3.6 or later, the order of fields in the data may be inconsistent after migration. This is due to differences in the database engine execution plans. If your business logic involves match queries on nested structures, evaluate the potential impact of inconsistent field order.

    • Before you migrate data, evaluate the performance of the source and destination databases. We also recommend that you perform data migration 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 server load.

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

    • DTS attempts to resume tasks that failed within the last seven days. Before you switch your workloads to the destination instance, stop or release the task, or revoke the write permissions from the account that DTS uses to access the destination instance. This prevents the task from being automatically resumed and the source data from overwriting the destination data.

    • Because DTS writes data concurrently, the storage space occupied by the destination is 5% to 10% larger than that of the source.

    • 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.

    • To query the number of documents in the destination MongoDB database, use the db.$table_name.aggregate([{ $count:"myCount"}]) syntax.

    • Ensure that the destination MongoDB database does not have the same primary key (default is _id) as the source database. Otherwise, data loss may occur. If the destination database has the same primary key as the source database, clear the relevant data in the destination database if it does not affect your business. This means deleting the documents in the destination database that have the same _id as the source database.

    • If a DTS task fails to run, DTS technical support will try to restore the task within 8 hours. During the restoration, the task may be restarted, and the parameters of the task may be modified.

      Note

      Only the parameters of the DTS task may be modified. The parameters of databases are not modified. The parameters that may be modified include but are not limited to the parameters in the "Modify instance parameters" section of the Modify the parameters of a DTS instance topic.

    • After you switch your business to the destination MongoDB database, you must ensure that your business operations comply with the requirements for sharded collections in that MongoDB database.

    Special cases

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

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

    • The latency of DTS is calculated by comparing the timestamp of the last migrated data entry in the destination database with the current timestamp. If the source database has not been updated for a long time, the latency information may be inaccurate. If the latency displayed for the task is too high, you can perform an update operation on the source database to refresh the latency information.

    Note

    If you choose to migrate the entire database, you can also create a heartbeat that periodically updates or writes 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 selected objects from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance.

    Note

    DTS supports schema migration for databases, collections, and indexes.

    Full data migration

    DTS migrates full data of objects from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance.

    Note

    DTS supports full data migration for databases and collections.

    Incremental data migration

    DTS migrates incremental data from the source ApsaraDB for MongoDB instance 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 ApsaraDB for MongoDB

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

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

    Destination ApsaraDB for MongoDB

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

    To create and grant permissions to database accounts for the source and destination ApsaraDB for MongoDB instances, see Use DMS to manage MongoDB database users.

    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.

      Category

      Configuration

      Description

      None

      Task Name

      The name of the DTS task. DTS automatically generates a task name. 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 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 source 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

      In this example, select Replica Set.

      • Replica Set: Deploys multiple nodes to achieve high availability and read/write splitting. For more information, see Replica set architecture.

      • Sharded Cluster: Provides three components: Mongos, shard, and Configserver. You can select the number and configurations of Mongos and shard nodes. For more information, see Sharded cluster architecture.

        Note

        If you set Architecture to Sharded Cluster, you must also specify Shard account and Shard password.

      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.

      Instance ID

      Select the ID of the source ApsaraDB for MongoDB instance.

      Authentication Database

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

      Database Account

      Enter the database account of the source 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.

      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

      In this example, select Sharded Cluster.

      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 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.

      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.

      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 the CIDR blocks of DTS servers.

      • If the source or destination database is a self-managed database and its Access Method is not set to Alibaba Cloud Instance, click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

    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, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.

        Source Objects

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

        Note

        You can select objects to migrate at the database or collection level.

        Selected Objects

        • To specify the name of the database in the destination MongoDB instance (sharded cluster architecture) that will receive the data:

          Right-click the destination database under Selected Objects. In the Edit Schema dialog box, change Schema Name to the name of the database in the destination MongoDB instance that will receive the data. For more information, see Map a single database or collection.

        • To specify the name of the collection in the destination MongoDB instance (sharded cluster architecture) that will receive the data:

          Right-click the collection under Selected Objects. In the Edit Table dialog box, change Table Name to the name of the collection in the destination MongoDB instance that will receive the data.

          Important

          You can specify the collection that will receive the data only when you migrate objects at the collection level.

        Note

        • To filter data, right-click the table to be migrated in the Selected Objects section and set filter conditions in the dialog box that appears. Data filtering is supported during full migration but not during incremental migration. For more information, see Set filter conditions.

        • If you use the object name mapping feature to specify the database or collection that will receive the data, the migration of other objects that depend on the mapped object may fail.

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

        Configuration

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. If you want to improve the stability of data migration tasks, purchase a dedicated cluster. For more information, see What is a DTS dedicated cluster.

        Retry Time for Failed Connections

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

        Note

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

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

        Retry Time for Other Issues

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

        Important

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

        Enable Throttling for Full Data Migration

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

        Note

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

        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

        If required, you can select an environment tag to identify the instance. 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.

      4. Click Next: Configure Database and Table Fields to set the default value for the ShardKey.

        1. In the row of the destination collection, click Set Default Value.

          Note

          If the value of Number of Shard Keys for a Table Name (collection) is 0, the destination collection does not have a sharding key and you do not need to set a default value.

        2. Select a Shard key default value type.

          Note

          Currently, Shard key default value type supports only string and int.

        3. Set the Default Value for the ShardKey.

          Important

          • The default ShardKey value takes effect only if the version of the destination MongoDB instance (sharded cluster architecture) is earlier than 4.4.

          • You must set default values for all ShardKeys in the objects to be migrated. Otherwise, a warning is reported during the Precheck step, and the task may fail.

    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 an 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.