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    Tair (Redis® OSS-Compatible):Data migration and synchronization FAQ

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    Tair (Redis® OSS-Compatible):Data migration and synchronization FAQ

    Last Updated:Jun 25, 2025

    This topic provides answers to 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 (key-value pairs) from Tair or open source Redis to another Tair or open source Redis. 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 (key-value pairs) from Tair or open source Redis to another Tair or open source Redis 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 in the source database remains unaffected.

    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 and data synchronization by using DTS?

    Comparison 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 ECS instances, and databases on third-party cloud platforms to Tair instances on Alibaba Cloud.

    Data synchronization is used for real-time data synchronization between Tair instances, such as from Instance A to Instance B. Data synchronization can be used in scenarios such as active geo-redundancy, disaster recovery, and data analytics.

    Availability range

    Support for data migration.

    Support for data synchronization.

    Feature

    Supports data migration across self-managed databases that are deployed in virtual private clouds (VPCs) owned by different Alibaba Cloud accounts.

    • Supports duplicate keys handling modes that you can specify.

    • Supports bidirectional synchronization between instances.

    • Supports data synchronization across self-managed databases that are deployed in VPCs owned by different Alibaba Cloud accounts.

    Billing rules and methods

    • You are not billed for schema migration and full data migration.

    • If you enable incremental data migration (optional), you are billed based on the duration of incremental migration (regardless of the amount of data migrated). Only the pay-as-you-go billing method is supported.

    • You are not billed for schema migration and full data migration.

    • After incremental data migration is started, you are billed based on the duration of incremental migration. The pay-as-you-go and subscription billing methods are supported.

    Note

    The data synchronization feature of DTS supports more Tair synchronization scenarios and features. We recommend that you use this feature to migrate data. For more information, see Data synchronization.

    Q: What do I do if an error occurs during a precheck?

    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 information about how to troubleshoot errors that occur during prechecks, see Precheck and troubleshooting and Troubleshoot precheck failures.