Use DTS to migrate a self-managed MongoDB replica set database to ApsaraDB for MongoDB - ApsaraDB for MongoDB

You can use Data Transmission Service (DTS) to migrate a self-managed MongoDB database that uses the replica set architecture to ApsaraDB for MongoDB. DTS supports full and incremental data migration. You can use both migration types to migrate your database to the cloud without interrupting your services.

You can also use MongoDB tools to migrate a self-managed database to a replica set instance. For more information about data migration and synchronization solutions, see Data migration and synchronization.

Prerequisites

The source self-managed MongoDB database and the destination ApsaraDB for MongoDB instance must be of supported versions. For more information, see Overview of migration solutions.
The destination ApsaraDB for MongoDB instance must have at least 10% more storage space than the source self-managed MongoDB database.

Usage notes

The configuration database is an internal system database. Do not migrate this database unless you have specific requirements.
DTS consumes resources from the source and destination databases during full data migration, which may increase the load on the database servers. If your database handles a high volume of traffic or if the server specifications are low, your database may experience high pressure or even become unavailable. Before you migrate data, carefully evaluate the impact of the migration. We recommend that you perform data migration during off-peak hours.
For information about the supported versions and storage engines of MongoDB instances, see Versions and storage engines. If you migrate data across different versions or storage engines, check for compatibility issues in advance.
The admin and local databases cannot be used as the source or destination database.
DTS writes data concurrently. This can cause the storage space that is occupied by the destination database to be 5% to 10% larger than that of the source database.
Ensure that the destination MongoDB database does not have documents with the same primary key (_id) as the source database. Otherwise, data loss may occur. If the destination database contains documents with the same primary key, you must clear the relevant data from the destination database without affecting your services. For example, you can delete the documents in the destination database that have the same _id as those in the source database.

Billing

Migration type	Task configuration fee	Data transfer cost
Full data migration	Free of charge.	You are charged for data transfer if you migrate data from Alibaba Cloud over the Internet. See Billing overview.
Incremental data migration	You are charged for this feature. See Billing overview.

Migration types

Full data migration: Migrates all historical data of the migration objects from the source MongoDB database to the destination MongoDB database.
Note
Databases, collections, and indexes can be migrated.
Incremental data migration: Migrates incremental data from the source MongoDB database to the destination MongoDB database after a full migration is complete.
Note
- The create and delete operations on databases, collections, and indexes can be synchronized.
- The create, delete, and update operations on documents can be synchronized.

Database account permissions

Data source	Full data migration	Incremental data migration
Self-managed MongoDB database	read permission on the database to be migrated	read permission on the database to be migrated, the admin database, and the local database
ApsaraDB for MongoDB database	readWrite permission on the destination database	readWrite permission on the destination database

To create and grant permissions to a database account:

For an ApsaraDB for MongoDB instance, see Manage MongoDB database users in DMS.
For a self-managed MongoDB database, see Create User in MongoDB.

Procedure

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

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	Parameter	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. In this example, Public IP Address is selected. Note If you select other connection types to connect to the self-managed database, you must complete the 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 included in the options, you can select a region that is 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 displayed only when Express Connect, VPN Gateway, or Smart Access Gateway, Public IP Address, or Cloud Enterprise Network (CEN) is selected as the connection type for the self-managed MongoDB database.
	Domain Name or IP	Enter the domain name or IP address of the self-managed MongoDB database. In this example, enter a public IP address. Note This parameter is displayed only when Endpoint Type is set to Standalone.
	Port Number	Enter the service port number of the self-managed MongoDB database. Note This parameter is displayed only when Endpoint Type is set to Standalone.
	Endpoint	Enter the connection address of the self-managed MongoDB database. Note This parameter is displayed only when Endpoint Type is set 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 connection addresses.
	Authentication Database	Enter the name of the database to which the database account of the self-managed MongoDB database belongs. If you have not changed the database, enter admin.
	Database Account	Enter the account of the corresponding mongos node in the self-managed MongoDB database. For information about the permissions that are required for the account, see Permissions required by database accounts. Note If Access Method of the self-managed MongoDB database is 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. If you have not changed the database, enter 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 permissions that are required for the account, see Permissions required by 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.

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.

Configure the objects to be migrated.

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

Parameter	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 icon to add the objects to the Selected Objects section. Note You can select databases or collections as the objects to migrate.
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 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.

Click Next: Advanced Settings to configure advanced settings.

Configuration	Description
Dedicated Cluster for Task Scheduling	By default, DTS schedules the task to the shared cluster if you do not specify a dedicated cluster. You can purchase a dedicated cluster of 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	The environment tag that is used to identify the DTS instance. You can select an environment tag as needed. 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: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.
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: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see the Configure monitoring and alerting when you create a DTS task section of the Configure monitoring and alerting topic.

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.

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.

Purchase an instance.

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

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?
New Instance Class	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.

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

More information

Connect to an ApsaraDB for MongoDB replica set instance