This topic describes how to use Data Transmission Service (DTS) to migrate ApsaraDB for MongoDB (Replica Set Architecture) to ApsaraDB for MongoDB (Replica Set Architecture or Sharded Cluster Architecture).
Supported source and destination databases
Source database (Replica Set Architecture) | Destination database (Replica Set Architecture, Sharded Cluster Architecture) |
ApsaraDB for MongoDB | ApsaraDB for MongoDB |
Self-managed database on ECS | Self-managed database on ECS |
Self-managed database accessed through leased line, VPN Gateway, or Smart Access Gateway | Self-managed database accessed through leased line, VPN Gateway, or Smart Access Gateway |
Self-managed database with a public IP address | Self-managed database with a public IP address |
This topic illustrates the configuration process using ApsaraDB for MongoDB (Replica Set Architecture) and ApsaraDB for MongoDB (either Replica Set or Sharded Cluster Architecture) as examples. The process for configuring other data sources follows a similar pattern.
Prerequisites
The source ApsaraDB for MongoDB with a Replica Set Architecture and the destination ApsaraDB for MongoDB, either with a Replica Set Architecture or a Sharded Cluster Architecture, have been established. For more information, see how to create a replica set instance and how to create a sharded cluster instance.
NoteFor supported versions, see Migration solutions overview.
We recommend that the storage space for the destination ApsaraDB for MongoDB be at least 10% larger than the space occupied by the source ApsaraDB for MongoDB.
If the destination ApsaraDB for MongoDB utilizes a sharded cluster architecture, you need to create the necessary databases and collections for sharding in the destination ApsaraDB for MongoDB according to your business requirements. This includes configuring data sharding, enabling the Balancer, and executing pre-sharding operations. For more information, see how to optimize Shard performance through data sharding and how to address uneven data distribution in a MongoDB sharded cluster.
NoteConfiguring data sharding can prevent data from being migrated to the same Shard, which would prevent the cluster from performing optimally. Enabling the Balancer and performing pre-sharding can prevent data skew issues.
Precautions
Category | Description |
Limits on the source database |
|
Other limits |
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Special cases | If the source database is a self-managed MongoDB database, take note of the following limits:
Note If you select an entire database as the object to be migrated, you can create a heartbeat table. The heartbeat table is updated or receives 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 | Migrate the structure of the migration object from the source ApsaraDB for MongoDB to the destination ApsaraDB for MongoDB. Note Objects that support schema migration include DATABASE, COLLECTION, and INDEX. |
Full migration | Migrate all historical data of the migration object from the source ApsaraDB for MongoDB to the destination ApsaraDB for MongoDB. Note Full migration supports data in DATABASE and COLLECTION. |
Incremental migration | On the basis of full migration, migrate the incremental updates from the source ApsaraDB for MongoDB to the destination ApsaraDB for MongoDB. Using OplogIncremental migration does not support databases created after the task starts running. The supported incremental updates are as follows:
Using ChangeStreamThe supported incremental updates are as follows:
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Permissions required for database accounts
Database | Schema migration | Full migration | Incremental migration |
Source ApsaraDB for MongoDB | Read permission on the database to be migrated and the config database. | Read permission on the database to be migrated, the admin database, and the local database. | |
Destination ApsaraDB for MongoDB | dbAdminAnyDatabase permission, read and write permissions on the destination database, and read permissions on the local database. |
For guidance on creating and authorizing database accounts for both source and destination ApsaraDB for MongoDB, refer to managing MongoDB database users with DMS.
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
Log on to the DTS console.
In the left-side navigation pane, click Data Migration.
In the upper-left corner of the page, select the region in which the data migration instance resides.
DMS console
NoteThe 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.
Log on to the DMS console.
In the top navigation bar, move the pointer over
.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.
Optional. Click New Configuration Page in the upper-right corner of the page.
NoteSkip this step if the Back to Previous Version button is displayed in the upper-right corner of the page.
Specific parameters in the new and previous versions of the configuration page may be different. We recommend that you use the new version of the configuration page.
Configure the source and destination databases. The following table describes the parameters.
WarningAfter 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
Configuration
Description
None
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
The instance that you want to use. You can choose whether to use an existing instance based on your business requirements.
If you select an existing instance, DTS automatically populates the parameters for the database.
If you do not use an existing instance, you must configure the database information below.
NoteYou can register a database with DTS on the Database Connections page or the new configuration page. For more information, see Manage database connections.
In the DMS console, you can select an existing database from the Select a DMS database instance. drop-down list. You can also click Add DMS Database Instance or go back to the homepage of the DMS console to register a database with DMS. For more information, see Register an Alibaba Cloud database instance and Register a database hosted on a third-party cloud service or a self-managed database.
Database Type
Select MongoDB.
Access Method
Select Cloud Instance.
Instance Region
Select the region where the source ApsaraDB for MongoDB resides.
Replicate Data Across Alibaba Cloud Accounts
In this example, a database instance of the current Alibaba Cloud account is used. Select No.
Architecture Type
Select Replica Set Architecture.
Replica Set Architecture: Achieve high availability and read/write splitting by deploying multiple nodes. For more information, see Replica Set Architecture.
Sharded Cluster Architecture: Provides three components: Mongos, Shard, and ConfigServer. You can freely choose the number and configuration of Mongos and Shard. For more information, see Sharded Cluster Architecture.
Migration Method
Select the method for incremental data migration based on your actual situation.
Oplog (recommended):
If the source database has enabled Oplog, this option is supported.
NoteLocal self-managed MongoDB and ApsaraDB for MongoDB have Oplog enabled by default. When migrating incremental data using this method, the delay of the incremental migration task is small (the speed of pulling logs is fast). Therefore, it is recommended to select Oplog.
ChangeStream: If the source database has enabled Change Streams (Change Streams), this option is supported.
NoteWhen the source database is Amazon DocumentDB (non-elastic cluster), only ChangeStream is supported.
When the Architecture of the source database is selected as Sharded Cluster, there is no need to fill in the Shard account and Shard password.
Instance ID
Select the instance ID of the source ApsaraDB for MongoDB.
Authentication Database Name
Enter the name of the database to which the database account of the source ApsaraDB for MongoDB instance belongs. If it has not been modified, the default is admin.
Database Account
Enter the database account of the source ApsaraDB for MongoDB. For permission requirements, see Permissions required for database accounts.
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.
NoteIf 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
The instance that you want to use. You can choose whether to use an existing instance based on your business requirements.
If you select an existing instance, DTS automatically populates the parameters for the database.
If you do not use an existing instance, you must configure the database information below.
NoteYou can register a database with DTS on the Database Connections page or the new configuration page. For more information, see Manage database connections.
In the DMS console, you can select an existing database from the Select a DMS database instance. drop-down list. You can also click Add DMS Database Instance or go back to the homepage of the DMS console to register a database with DMS. For more information, see Register an Alibaba Cloud database instance and Register a database hosted on a third-party cloud service or a self-managed database.
Database Type
Select MongoDB.
Access Method
Select Cloud Instance.
Instance Region
Select the region where the destination ApsaraDB for MongoDB resides.
Replicate Data Across Alibaba Cloud Accounts
In this example, a database instance of the current Alibaba Cloud account is used. Select No.
Architecture Type
Select the architecture based on your business needs. Valid values:
Replica Set Architecture: Achieve high availability and read/write splitting by deploying multiple nodes. For more information, see Replica Set Architecture.
Sharded Cluster Architecture: Provides three components: Mongos, Shard, and ConfigServer. You can freely choose the number and configuration of Mongos and Shard. For more information, see Sharded Cluster Architecture.
Instance ID
Select the instance ID of the destination ApsaraDB for MongoDB.
Authentication Database Name
Enter the name of the database to which the database account of the destination ApsaraDB for MongoDB instance belongs. If it has not been modified, the default is admin.
Database Account
Enter the database account of the destination ApsaraDB for MongoDB. For permission requirements, see Permissions required for 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.
NoteIf 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.
Click Test Connectivity and Proceed in the lower part of the page.
NoteMake 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.
Configure the objects to be migrated.
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.
NoteIf 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.
For more information about task steps, see Migration types.
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 Instance
You can set the capitalization policy for database and collection names of the objects being migrated to the destination instance. By default, the DTS Default Policy is selected. Alternatively, you can opt to align with the source and destination databases' default policies. For more information, see Capitalization policy for object names in the destination database.
Source Objects
In the Source Database Objects box, select the objects you want to migrate, and then click
to transfer them to the Selected Objects box.
NoteThe selection granularity of migration objects is DATABASE and COLLECTION.
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.
NoteIf you need to perform incremental migration operations at the database or collection level, right-click the object you want to migrate within the Selected Objects list and choose your option from the pop-up dialog box.
If you need to establish filter conditions for data (supported during full migration but not during incremental migration), right-click the desired table in the Selected Objects list and configure them in the dialog box that appears. For details on how to configure these settings, see Set filter conditions.
If the object name mapping feature (specifying the database or collection to receive data) is used, it may cause migration failures for other objects that depend on this object.
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.
NoteIf 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.
ImportantThe 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.
NoteYou 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 single table
For the data to be migrated, whether the data type of the primary key
_id
is unique within the same collection.NoteThis configuration is only available when the Migration Types is set to Full Data Migration.
Yes: Unique. DTS does not scan the data type of the primary key in the source data during the full migration phase from the source database.
No: Indicates non-uniqueness. During the full migration phase, DTS scans the data type of the primary key in the source data slated for migration from the source database.
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.
NoteYou can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
Environment Tag
You can select an environment tag to identify the instance based on your actual needs. 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.
NoteBefore 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?
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.