This topic describes how to migrate a standalone instance or a replica set instance across regions 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

Background information

You may need to migrate the data of an ApsaraDB for MongoDB instance across regions in the following situations:

  • Restructure your business.
  • Use an ApsaraDB for MongoDB instance to provide database services for applications deployed on an Elastic Compute Service (ECS) instance. However, the ApsaraDB for MongoDB instance and the ECS instance are not in the same region.

In this example, an ApsaraDB for MongoDB instance in the China (Qingdao) region is migrated to an ApsaraDB for MongoDB instance in the China (Hangzhou) region.

Migrate data between ApsaraDB for MongoDB instances across regions
Note This example describes only how to migrate data from the source instance. After data is migrated, you can release the source instance if you no longer need the source instance.

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.
  • To ensure data consistency, we recommend that you do not write data to the source instance when full data migration of a standalone instance is in progress.
  • 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.
  • To ensure better performance and stability of the instance, the system will upgrade the minor version to the latest version by default. If the minor version of your instance expires or is not included in the maintenance list and the instance is upgraded, migrated, changed, Created from a backup, Created by point-in-time, or performed Restore data to a new ApsaraDB for MongoDB instance.
  • 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

Database Full data migration Incremental data migration
Source ApsaraDB for MongoDB instance The read permissions on the source database The read permissions on the source database, the admin database, and the local database
Destination ApsaraDB for MongoDB 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.

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 ApsaraDB for MongoDB 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. In this example, select China (Qingdao).
    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. In this example, select China (Hangzhou).
    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.
    Setting Description
    Select the migration types
    • To perform only full data migration, select only Full Data Migration.
    • To ensure service continuity during data migration, select Full Data Migration and Incremental Data Migration.
    Note
    • DTS does not support incremental data migration for standalone instances.
    • If Incremental Data Migration is not selected, we recommend that you do not write data to the source database during full data migration. This ensures data consistency between the source and destination databases.
    Select the objects to be migrated
    • Select one or more objects from the Available section and click the 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 database. 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.
  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

What to do next

Determine whether to release the source instance.

  • If the source instance uses the pay-as-you-go billing method, you can release the source instance. For more information, see Release an ApsaraDB for MongoDB instance.
  • If the source instance uses the subscription billing method, you cannot release the source instance.