This topic describes how to migrate data from a replica set MongoDB instance to a sharded cluster instance by using Data Transmission Service (DTS). DTS supports full data migration and incremental data migration. When you migrate data between ApsaraDB for MongoDB instances, you can select both of the supported migration types to ensure service continuity.

Prerequisites

Each shard in the destination sharded cluster instance has sufficient storage space.

Precautions

  • DTS consumes the resources of the source and destination instances during full data migration. This may increase the loads of the database servers. If you migrate a large volume of data or the server specifications cannot meet your requirements, database services may become unavailable. 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.
  • If the source and destination MongoDB databases use different versions or storage engines, make sure that your applications can run on both databases. For more information about the versions and storage engines that are supported by ApsaraDB for MongoDB, see MongoDB versions and storage engines.
  • The admin or local database cannot be used as the source or destination database.

Billing

Migration type Task configuration fee Internet traffic fee
Full data migration Free of charge Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see DTS pricing.
Incremental data migration Charged. For more information, see DTS pricing.

Migration types

Migration type Description
Full data migration DTS migrates all historical data of the required objects from the source MongoDB database to the destination MongoDB database.
Note The following types of objects are supported: database, collection, and index.
Incremental data migration After full data migration is complete, DTS synchronizes incremental data from the source MongoDB database to the destination MongoDB database.
Note
  • The create and delete operations that are performed on databases, collections, and indexes can be synchronized.
  • The create, delete, and update operations that are performed on documents can be synchronized.

Permissions required for database accounts

Instance Full data migration Incremental data migration
ApsaraDB for MongoDB replica set instance The read permissions on the source database The read permissions on the source database, the admin database, and the local database
ApsaraDB for MongoDB sharded cluster instance The read and write permissions on the destination database The read and write permissions on the destination database
Note For more information about how to create and authorize a database account, see Manage user permissions on MongoDB databases.

Before you begin

Create databases and collections to be sharded in the destination ApsaraDB for MongoDB instance, and configure data sharding based on your business requirements. For more information, see Configure sharding to maximize the performance of shards.

Note After you configure sharding for a cluster, data will not be migrated to the same shard. This maximizes the performance of the sharded cluster.

Procedure

  1. Log on to the DTS console.
  2. In the left-side navigation pane, click Data Migration.
  3. At the top of the Migration Tasks page, select the region where the destination ApsaraDB for MongoDB instance resides.
    Select a region
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Configure the source and destination databases.
    Configure the source and destination databases
    Section Parameter Description
    N/A Task Name DTS automatically generates a task name. We recommend that you specify an informative name for easy identification. You do not need to use a unique task name.
    Source Database Instance Type Select ApsaraDB for MongoDB.
    Instance Region Select the region where the source ApsaraDB for MongoDB instance resides.
    MongoDB Instance ID Select the ID of the source ApsaraDB for MongoDB instance.
    Database Name Enter the name of the authentication database. The database account is created in this database.
    Database Account Enter the database account of the source ApsaraDB for MongoDB instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password Enter the password of the database account.
    Note After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the source database parameters based on the check results.
    Destination Database Instance Type Select MongoDB Instance.
    Instance Region Select the region where the destination ApsaraDB for MongoDB instance resides.
    MongoDB Instance ID Select the ID of the destination ApsaraDB for MongoDB instance.
    Database Name Enter the name of the authentication database. The database account is created in this database.
    Database Account Enter the database account of the destination ApsaraDB for MongoDB instance. For more information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password Enter the password of the database account.
    Note After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the destination database parameters based on the check results.
  6. In the lower-right corner, click Set Whitelist and Next.
    Note DTS adds the CIDR blocks of DTS servers to the whitelists of the source and destination ApsaraDB for MongoDB instances. This ensures that DTS servers can connect to the source and destination ApsaraDB for MongoDB instances. After data migration is complete, you can remove the CIDR blocks of DTS servers from the whitelists. For more information, see Configure a whitelist for a sharded cluster instance.
  7. Select the migration types and the objects to be migrated.
    Select the migration types and the objects to be migrated
    Setting Description
    Select the migration types
    • To perform only full data migration, select Full Data Migration.
    • To ensure service continuity during data migration, select Full Data Migration and Incremental Data Migration.
    Note If Incremental Data Migration is not selected, do not write data to the source ApsaraDB for MongoDB instance during full data migration. This ensures data consistency between the source and destination instances.
    Select the objects to be migrated
    • Select one or more objects from the Available section and click the Rightwards arrow icon to move the objects to the Selected section.
      Note DTS cannot migrate data from the admin or local database.
    • You can select databases, collections, or functions as the objects to be migrated.
    • By default, after an object is migrated to the destination database, the name of the object remains unchanged. You can use the object name mapping feature to rename the objects that are migrated to the destination instance. For more information, see Object name mapping.
    Specify whether to rename objects You can use the object name mapping feature to rename the objects that are migrated to the destination instance. For more information, see Object name mapping.
    Specify the retry time for failed connections to the source or destination database By default, if DTS fails to connect to the source or destination database, DTS retries within the next 12 hours. You can specify the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
    Specify whether to copy temporary tables to the destination database when DMS performs online DDL operations on the source table If you use Data Management (DMS) to perform online DDL operations on the source database, you can specify whether to migrate temporary tables generated by online DDL operations.
    • Yes: DTS migrates the data of temporary tables generated by online DDL operations.
      Note If online DDL operations generate a large amount of data, the data migration task may be delayed.
    • No: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL data of the source database is migrated.
      Note If you select No, the tables in the destination database may be locked.
  8. In the lower-right corner of the page, click Precheck.
    Note
    • Before you can start the data migration task, a precheck is performed. You can start the data migration task only after the task passes the precheck.
    • If the task fails to pass the precheck, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  9. After the task passes the precheck, click Next.
  10. In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the data migration task.
    • Full data migration

      We recommend that you do not manually stop the task during full data migration. Otherwise, the data migrated to the destination database will be incomplete. You can wait until the data migration task automatically stops.

    • Incremental data migration

      The task does not automatically stop during incremental data migration. You must manually stop the task.

      Note We recommend that you select an appropriate time to manually stop the data migration task. For example, you can stop the task during off-peak hours or before you switch your workloads to the destination ApsaraDB for MongoDB instance.
      1. Wait until Incremental Data Migration and The migration task is not delayed appear in the progress bar of the migration task. Then, stop writing data to the source database for a few minutes. The delay time of incremental data migration may be displayed in the progress bar.
      2. After the status of incremental data migration changes to The migration task is not delayed again, manually stop the migration task. Incremental data migration without delay
  12. Switch your workloads to the destination ApsaraDB for MongoDB instance.