ApsaraDB for MongoDB:Migrate data between ApsaraDB for MongoDB instances of different Alibaba Cloud accounts

Prerequisites

• The source instance is a standalone instance or a replica set instance. If the source instance is a sharded cluster instance, we recommend that you use the built-in commands of MongoDB to migrate data. For more information, see Migrate a self-managed MongoDB database to ApsaraDB for MongoDB by using tools provided by MongoDB.
  Note DTS does not support incremental data migration from a standalone instance. For more information, see Migration types.
• The destination instance is created in the destination region. For more information, see Create a standalone instance, Create a replica set instance, or Create a sharded cluster instance.
  Note 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 consumes the resources of the source and destination databases during full data migration. This may increase the loads on the database servers. If the loads on the database servers are high or the server specifications do not meet the migration 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.
• 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 MongoDB database does not have the same primary key as the source database. The default primary key is _id. Otherwise, data loss may occur in the destination database. If the destination database has the same primary key as the source database, clear the related data in the destination database without interrupting the services of DTS. If the same primary key is _id, you can delete the data in the destination database that has the same _id as the source database.

Billing

Migration types

Permissions required for database accounts

Preparations

1. Log on to the ApsaraDB for MongoDB console by using the Alibaba Cloud account that owns the source instance.
2. Apply for a public endpoint for the source instance. For more information, see Apply for a public endpoint.
3. Add the CIDR blocks of DTS servers to the whitelist of the source instance. For more information, see Modify the IP address whitelist of an ApsaraDB for MongoDB instance.
   Note You can determine the CIDR blocks you need to add based on the region in which the destination instance resides. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.

   For example, if the source instance resides in the China (Hangzhou) region and the destination instance resides in the China (Shenzhen) region, you must add the CIDR blocks of DTS servers in the China (Shenzhen) region to the whitelist of the source instance.

Procedure

1. Log on to the ApsaraDB for MongoDB console.
   
2. In the left-side navigation pane, click Replica Set Instances or Sharded Cluster Instances based on the instance type.
   
3. In the upper-left corner of the page, select the resource group and region to which the instance belongs.
   
4. Click the ID of an instance, or click in the Actions column corresponding to the instance and select Manage.
   
5. In the upper-right corner of the instance details page, click Migrate Databases.
   
6. On the Create Migration Task page, create a data migration task.
   1. Configure the source and destination databases.
      

      Section	Parameter	Description
      N/A	Task Name	The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
      Source Database	Instance Type	The instance type of the source database. In this example, User-Created Database with Public IP Address is selected.
      	Instance Region	The region in which the source instance resides.
      	Database Type	The type of the source database. Select MongoDB.
      	Hostname or IP Address	The domain name obtained from the public endpoint of the source instance. Example: dds-bp1b47357f218e74****-pub.mongodb.rds.aliyuncs.com.
      	Port Number	The service port of the source instance. In this example, 3717 is used.
      	Database Name	The name of the authentication database. The database account is created in this database. Note If you want to use the root account, enter admin in the Database Name field.
      	Database Account	The username of the account that is used to connect to the source 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. Note After you specify the information about the source database, you can click Test Connectivity next to Database Password to check whether the information is correct. If the information is correct, the Passed message is displayed. Otherwise, the Failed message is displayed and you must click Check next to the Failed message to modify the information.
      	Encryption	Specifies whether to encrypt the connection. Select Non-encrypted or SSL-encrypted based on your business requirements. If you select SSL-encrypted, you must enable SSL encryption for the source instance before you configure the data migration task. Note You can select SSL-encrypted only for MongoDB Atlas databases. If you select SSL-encrypted, more CPU resources are consumed.
      Destination Database	Instance Type	The instance type of the destination database. Select MongoDB Instance.
      	Instance Region	The region in which the destination ApsaraDB for MongoDB instance resides.
      	MongoDB Instance ID	The ID of the destination instance.
      	Database Name	The name of the authentication database. The database account is created in this database. Note If you want to use the root account, enter admin in the Database Name field.
      	Database Account	The username of the account that is used to connect to the destination 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. Note After you specify the information about the destination database, you can click Test Connectivity next to Database Password to check whether the information is correct. If the information is correct, the Passed message is displayed. Otherwise, the Failed message is displayed and you must click Check next to the Failed message to modify the information.

   2. In the lower-right corner of the page, click Set Whitelist and Next.
      Warning If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, 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.
   3. Select the migration types and the objects to be migrated.
      

      Setting	Description
      Select the migration types	To ensure data consistency, we recommend that you select both Full Data Migration and Incremental Data Migration. If you select only Full Data Migration, the data updated during full data migration may not be migrated from the source instance to the destination instance. If you select only Incremental Data Migration, take note of the following items: After the migration task is started, DTS migrates only incremental data generated in the source instance. Triggers cannot be synchronized during incremental data migration. For more information, see Configure a data synchronization task for a source database that contains a trigger. 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 instance during full data migration. This ensures data consistency between the source and destination instances.
      Select the objects to be migrated	To select the objects to be migrated, perform the following steps: Select one or more objects from the Available section. Click the icon to add the objects to the Selected section. Note DTS cannot migrate data from the admin or local database. The objects that you can migrate are databases, collections, and functions. By default, after an object is migrated to the destination instance, the name of the object remains unchanged. If you want to rename an object in the destination instance, you can use the object name mapping feature. 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 range for failed connections to the source or destination database	By default, if DTS fails to connect to the source and destination databases, DTS retries within the next 12 hours. You can specify the retry time range based on your business requirements. If DTS reconnects 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 Within the time range in which DTS attempts to reconnect to the source and destination databases, 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 and destination databases are released.

   4. In the lower-right corner of the page, click 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 error message, you can run a precheck again.

      • If an alert is triggered for an item during the precheck:

        • If the 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.

   5. After the data migration task passes the precheck, click Next.
   6. In the Confirm Settings dialog box, configure the Instance Class parameter. Then, read and select the check box to agree to Data Transmission Service (Pay-As-You-Go) Service Terms.
   7. Click Buy and Start to start the data migration task.
7. View the progress of the 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 may be incomplete. You can wait until the full data migration task automatically stops.

   • Incremental data migration

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

   1. Wait until Incremental Data Migration and The migration task is not delayed appear in the progress bar of the data migration task. Then, stop writing data to the source instance for a few minutes. The latency of incremental data migration may be displayed in the progress bar.
   2. Wait until the status of incremental data migration changes to The migration task is not delayed again. Then, manually stop the migration task.
8. 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

If you migrate data to a sharded cluster instance, you can configure data sharding based on your business requirements. For more information, see Configure sharding to maximize the performance of shards.