This topic provides answers to some frequently asked questions about data migration and data synchronization.

Q: What are data migration and data synchronization?

  • A: Data migration allows you to migrate data stored in key-value pairs from one Redis database to another Redis database. In most cases, the migration task stops after all data is migrated. The migration task is a one-time task.
  • Data synchronization allows you to synchronize data stored in key-value pairs from one Redis database to another Redis database in real time. In most cases, the data synchronization task continuously runs to maintain data consistency between the source and destination databases.
Note Data migration and data synchronization replicate data from the source database to the destination database. The data of the source database remains unaffected.

Q: Which one can I choose for data migration or data synchronization, Data Transmission Service (DTS) or redis-shake?

A: We recommend that you use DTS. You can manage data migration or data synchronization tasks in a visualized console. No additional resources are required to deploy software. This simplifies the configuration process of data migration and data synchronization tasks. To solve issues when you use DTS, submit a ticket.

For more information about how to configure data migration or data synchronization tasks, see Overview of data migration and Overview of data synchronization.

Q: How do data migration and data synchronization work?

A: For more information, see System architecture and design concepts.

Q: What is the difference between data migration or data synchronization by using DTS?

Item Data migration Data synchronization
Scenario The data migration feature is used to migrate data from on-premises databases, self-managed databases that are hosted on Elastic Compute Service (ECS) instances, and databases on third-party cloud platforms to Alibaba Cloud. Data synchronization is used for real-time data synchronization between two Redis databases, for example, from Instance A to Instance B. Data synchronization can be used in scenarios such as active geo-redundancy, disaster recovery, and data analytics.
Feature support Support for data migration. Support for data synchronization.
Features You can read and migrate data across self-managed databases that are deployed in virtual private clouds (VPCs) owned by different Alibaba Cloud accounts.
  • You can specify how duplicate keys are handled.
  • You can configure two-way data synchronization between ApsaraDB for Redis instances
  • You can read and synchronize data across self-managed databases that are deployed in VPCs owned by different Alibaba Cloud accounts.
Billing method Only the pay-as-you-go billing method is supported. The pay-as-you-go and subscription billing methods are supported.
Billing rules You are billed when incremental data migration is in progress. This includes the period when incremental data migration is paused. You are not billed for schema migration and full data migration.
  • If you use the pay-as-you-go billing method, billing starts after the task is configured and started. You are also billed when the task is paused.
  • If you use the subscription billing method, the fee is deducted at the time of purchase based on the selected quantity and configurations.
Note The data synchronization feature of DTS is suitable for more scenarios. We recommend that you use the data synchronization feature of DTS to migrate data. For more information, see Overview of data synchronization.

Q: How can I resolve precheck errors when I use DTS?

A: Before you perform a data migration or data synchronization task, DTS runs a precheck on the source and destination databases to ensure that the task can run as expected. For more information about how to troubleshoot the errors, see Troubleshoot precheck failures and Troubleshoot precheck failures.

Q: How can I troubleshoot redis-shake errors?

A: For more information about how to troubleshoot the errors, see FAQ.