ApsaraDB for MongoDB provides standalone instances, replica set instances, and sharded cluster instances. Standalone instances are suitable in development environments and test environments that store unimportant data. Replica set instances and sharded cluster instances are suitable in production environments. This topic describes how to migrate data from a standalone instance to a replica set instance or sharded cluster instance by using Data Transmission Service (DTS).

Prerequisites

The available storage space of the destination instance is 10% larger than the total size of the data in the source instance. This is a recommended prerequisite.

Usage notes

  • DTS uses the resources of the source and destination databases during full data migration. This may increase the loads on the database servers. If you migrate a large amount of data or if the server specifications do not 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.
  • DTS does not support incremental data migration from a standalone instance. To ensure data consistency, do not write data to the source instance during full data migration.
  • If the source and destination ApsaraDB for MongoDB instances have different versions or storage engines, make sure that the versions or storage engines are compatible. For more information, see MongoDB versions and storage engines.
  • ApsaraDB for MongoDB automatically updates the minor version of the instance to the latest version if the minor version of an ApsaraDB for MongoDB instance expires or is not included in the maintenance list and when you perform some operations. This ensures that the ApsaraDB for MongoDB instance can provide higher performance and stability. For more information, see Database version upgrade, Data migration, Overview, Restore backup data to a new ApsaraDB for MongoDB instance by backup point, Restore backup data to a new ApsaraDB for MongoDB instance by point in time, and Restore one or more databases of an ApsaraDB for MongoDB instance.
  • DTS cannot migrate data from the admin or local database.
  • 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.
  • Make sure that the destination ApsaraDB for MongoDB instance does not have the same primary key as that in the source instance. The default primary key is _id. Otherwise, data may be lost. If the destination instance has the same primary key as that in the source instance, delete the same document that corresponds to the _id primary key in the destination instance as that in the source instance without affecting your business.

Billing

Migration typeTask configuration feeInternet traffic fee
Full data migrationFree of charge.Free of charge.

Migration types

Full data migration: DTS migrates all existing data of the source MongoDB database to the destination MongoDB database.

Note Full data migration is supported for databases, collections, and indexes.

Permissions required for database accounts

InstancePermission
Source ApsaraDB for MongoDB instanceRead permissions on the source database
Destination ApsaraDB for MongoDB instanceRead and write permissions on the destination database

For more information about how to create a database account and grant permissions to the database account, see Manage MongoDB databases by using DMS.

Procedure

  1. Go to the configuration page of the data migration task.
    1. Log on to the ApsaraDB for MongoDB console.
    2. In the left-side navigation pane, click Replica Set Instances.
    3. In the upper-left corner of the page that appears, select the resource group and region to which the standalone ApsaraDB for MongoDB instance belongs.
    4. Find the instance that you want to manage and click the ID of the instance.
    5. In the upper-right corner of the page that appears, click Migrate Databases.
  2. Configure the source and destination databases.
    SectionParameterDescription
    N/ATask Name

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

    Source DatabaseSelect Instance
    Select whether to use an existing instance.
    • If you select an existing instance, DTS automatically applies the parameter settings of the instance. You do not need to configure the corresponding parameters again.
    • If you do not use an existing instance, you must configure parameters for the source database.
    Database TypeThe type of the source database. Select MongoDB.
    Access MethodThe access method of the source database. Select Alibaba Cloud Instance.
    Instance RegionThe region in which the source ApsaraDB for MongoDB instance resides.
    ArchitectureThe architecture in which the source instance is deployed. Select Replica Set for a standalone ApsaraDB for MongoDB instance.
    • Replica Set: You can deploy multiple types of nodes on a replica set instance to achieve high availability and read/write splitting. For more information, see Replica set instances.
    • Sharded Cluster: A sharded cluster instance consists of three types of components: mongos, shard, and Configserver nodes. You can customize the configurations and number of mongos and shard nodes. For more information, see Sharded cluster instances.
    Instance IDThe ID of the source ApsaraDB for MongoDB instance.
    Authentication DatabaseThe name of the authentication database to which the objects to be migrated in the source ApsaraDB for MongoDB instance belong. If you did not change the name before, the default value is admin.
    Database AccountThe database account of the source ApsaraDB for MongoDB instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password

    The password of the database account.

    Destination DatabaseSelect Instance
    Select whether to use an existing instance.
    • If you select an existing instance, DTS automatically applies the parameter settings of the instance. You do not need to configure the corresponding parameters again.
    • If you do not use an existing instance, you must configure parameters for the source database.
    Database TypeThe type of the destination database. Select MongoDB.
    Access MethodThe access method of the destination database. Select Alibaba Cloud Instance.
    Instance RegionThe region in which the destination ApsaraDB for MongoDB instance resides.
    ArchitectureThe architecture in which the destination instance is deployed. Select an architecture based on your business requirements. Valid values:
    • Replica Set: You can deploy multiple types of nodes on a replica set instance to achieve high availability and read/write splitting. For more information, see Replica set instances.
    • Sharded Cluster: A sharded cluster instance consists of three types of components: mongos, shard, and config server nodes. You can customize the configurations and number of mongos and shard nodes. For more information, see Sharded cluster instances.
    Instance IDThe ID of the destination ApsaraDB for MongoDB instance.
    Authentication DatabaseThe name of the authentication database to which the objects to be migrated in the destination ApsaraDB for MongoDB instance belong. If you did not change the name before, the default value is admin.
    Database AccountThe database account of the destination ApsaraDB for MongoDB instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password

    The password of the database account.

  3. In the lower part of the page, click Test Connectivity and Proceed.
    If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must make sure that the ECS instance can access the database. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information about the CIDR blocks of DTS servers, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
    Warning If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database or an instance, or to the security group rules of an ECS instance, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhance the security of your username and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
  4. Configure objects to migrate and advanced settings.
    ParameterDescription
    Migration Type
    Select both Schema Migration and Full Data Migration.
    Note In this scenario, DTS does not support incremental data migration. To ensure data consistency, we recommend that you do not write data to the source instance during data migration.
    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 identical collection names, the precheck is passed. Otherwise, an error is returned during the precheck, and the data migration task cannot be started.
      Note You can use the object name mapping feature to rename the collections that are migrated to the destination database. You can use this feature if the source and destination databases contain identical collection names and the collections in the destination database cannot be deleted or renamed. 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 inconsistency may occur, 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 some columns are migrated, or the data migration task fails.
    Capitalization of Object Names in Destination InstanceThe 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 ObjectsSelect one or more objects from the Available section. Click the Rightwards arrow icon and add the objects to the Selected section.
    Note You can select databases or collections as the objects to be migrated.
    Selected Objects
    • To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
    • To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
    Note
    • If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
    • To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information about the procedure, see Use SQL conditions to filter data.
  5. Click Next: Advanced Settings to configure advanced settings.
    ParameterDescription
    Set Alerts
    Specifies whether to set alerts for the data migration task. If the task fails or the migration latency exceeds the threshold, the alert contacts will receive notifications. Valid values:
    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 time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note
    • If you set different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is set later takes precedence.
    • If DTS retries a connection, you are charged for the operation of the DTS instance. We recommend that you specify the retry time based on your business needs and release the DTS instance at your earliest opportunity after the source and destination instances are released.
    Configure ETLSpecify whether to enable the extract, transform, and load (ETL) feature. Select Yes or No based on your business requirements. If you select Yes, you must enter domain-specific language (DSL) statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task.
  6. In the lower part of the page, click Next: Save Task Settings and Precheck.
    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 troubleshoot the issues based on the causes, 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 an alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur, and your business may be exposed to potential risks.
  7. Wait until the Success Rate value becomes 100%. Then, click Next: Purchase Instance.
  8. On the Purchase Instance page, specify the Instance Class parameter for the data migration instance. The following table describes the parameter.
    SectionParameterDescription
    ParametersInstance Class

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

  9. Read and select the check box to agree to Data Transmission Service (Pay-as-you-go) Service Terms.
  10. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.
  11. Switch your workloads to the destination ApsaraDB for MongoDB instance.

What to do next

If you no longer need the source instance, release the source instance.

  • If the source instance is charged based on the pay-as-you-go billing method, you can release the instance. For more information, see Release an instance.
  • If the source instance is charged based on the subscription billing method, you are not allowed to release the instance.

References