Data Transmission Service:Migrate data from a Db2 for LUW database to a PolarDB-X instance

Prerequisites

• The source Db2 for LUW database and the destination PolarDB-X V2.0 instance are created. For more information about the supported versions of the source database and the destination instance, see Overview of data migration scenarios.
  Note The PolarDB-X V2.0 instance is compatible with MySQL 5.7.
• The available storage space of the destination instance is larger than the total size of the data in the source database.

Precautions

Migration types

• Full data migration

  DTS migrates historical data of the required objects from the source database to the destination database.

• Incremental data migration

  After full data migration is completed, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows you to ensure service continuity during data migration.

SQL operations that can be migrated

Permissions required for database accounts

Preparations

If you want to implement an incremental data migration, you must enable the archive logging for the Db2 for LUW database. For more information, see Primary log archive method and Secondary log archive method.

Procedure

1. Go to the Data Migration page of the new DTS console.
   Note You can also log on to the Data Management (DMS) console. In the top navigation bar, click DTS.
2. In the upper-left corner of the page, select the region in which the data migration instance resides.
   
3. Click Create Task. On the page that appears, configure the source and destination databases.
   Warning After you select the source and destination instances, we recommend that you read the limits displayed at the top of the page. This helps you create and run the data migration task.

   

   Section	Parameter	Description
   None	Task Name	DTS automatically generates a task name. We recommend that you specify a descriptive name that makes it easy to identify. You do not need to use a unique task name.
   Source Database	Database Type	Select DB2 LUW.
   	Access Method	Select Public IP Address.
   	Instance Region	Select the region in which the source Db2 for LUW database resides.
   	IP Address	Enter the endpoint that is used to connect to the Db2 for LUW database. In this example, enter the public IP address.
   	Port Number	Enter the port number of the Db2 for LUW database, which must be accessible over the Internet. Default value: 50000.
   	Database Name	Enter the name of the source Db2 for LUW database.
   	Database Account	Enter the database account of the source Db2 for LUW database. For 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.
   	Encryption	Select Non-encrypted or SSL-encrypted based on your requirements. If you want to select SSL-encrypted, you must enable SSL encryption for the source instance before you configure the data migration task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance.
   Destination Database	Database Type	Select PolarDB-X 2.0.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	Select the region in which the destination PolarDB-X V2.0 instance resides.
   	Instance ID	Select the destination PolarDB-X V2.0 instance.
   	Database Account	Enter the database account of the destination PolarDB-X V2.0 instance. For 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.

4. In the lower part of the page, click Test Connectivity and Proceed.
   Warning

   • If the source or destination database instance is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, or is a self-managed database hosted on Elastic Compute Service (ECS), DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database.
   • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database instance or 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 account 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.
   • After the DTS task is completed or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
5. Configure objects to migrate and advanced settings.
   • Basic Settings

     Parameter	Description
     Task Stages	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 If Incremental Data Migration is not selected, we recommend that you do not write data to the source instance during data migration. This ensures data consistency between the source and destination instances.
     Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain identical table names, the precheck is passed. Otherwise, an error is returned during precheck and the data migration task cannot be started. Note You can use the object name mapping feature to rename the tables that are migrated to the destination database. You can use this feature if the source and destination databases contain identical table names and the tables 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 table 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. If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails.
     Select Objects	Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section.
     Rename Databases and Tables	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 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.
     Filter data	You can specify WHERE conditions to filter data. For more information, see Use SQL conditions to filter data.
     	In the Selected Objects section, right-click an object. In the dialog box that appears, select the DML operations that you want to migrate. For more information, see SQL operations that can be migrated.

   • Advanced Settings

     Parameter	Description
     Set Alerts	Specify 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. Select No if you do not want to set alerts. Select Yes to set alerts. In this case, you must also set the alert threshold and alert contacts.
     Retry Time for Failed Connections	Specify the retry time range for failed connections. Valid values: 10 to 720. Unit: minutes. Default value: 720. We recommend that you set the retry time range to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Note If an instance serves as the source or destination database of multiple data synchronization tasks, the value that is set 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 needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.

6. 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, you can click the 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.
7. Wait until the Success Rate 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.

   Section	Parameter	Description
   Parameters	Instance Class	DTS provides various migration specifications. The migration speed varies based on the migration specifications that you select based on your business requirements. For more information, see Specifications of data migration instances.

9. Read and select 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.