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    Data Transmission Service:One-way synchronization across Alibaba Cloud accounts

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    Data Transmission Service:One-way synchronization across Alibaba Cloud accounts

    Last Updated:Apr 21, 2026

    Data Transmission Service (DTS) supports various scenarios, such as resource migration, account consolidation, and business architecture adjustments.

    Prerequisites

    You have created a destination Tair (Redis OSS-Compatible) instance with a storage capacity greater than the used storage of the source Tair (Redis OSS-Compatible) instance.

    Note

    For information about supported versions, see Overview of data synchronization scenarios.

    Background

    This topic describes how to synchronize data from a source Redis instance in one Alibaba Cloud account (Account A) to a destination instance in another (Account B).

    To use DTS for one-way synchronization of Tair (Redis OSS-Compatible) data across accounts, configure the task as follows.

    Step

    Description

    1. Log on to the Alibaba Cloud Management console with the Alibaba Cloud account that owns the source database and configure RAM role authorization. For more information, see Configure RAM authorization for cross-account DTS tasks.

    Configure a RAM role to set the Alibaba Cloud account that owns the destination database as a trusted account and authorize it to access the cloud resources of the current account.

    2. Log on to the Alibaba Cloud Management console with the primary account that owns the destination database and configure the data synchronization task. For more information, see Procedure.

    DTS can directly read information from the source Redis instance across Alibaba Cloud accounts.

    Limitations

    Type

    Description

    Source database limitations

    • To ensure synchronization quality, DTS inserts a key prefixed with DTS_REDIS_TIMESTAMP_HEARTBEAT into the source database to record update timestamps. If the source database uses a cluster architecture, DTS inserts this key into each shard. This key is filtered out during synchronization and expires after the task is complete.

    • If the source database is a read-only instance or the DTS account does not have write (SETEX) permissions, the reported latency may be inaccurate.

    • DTS relies on the Redis replication backlog mechanism. To ensure a stable synchronization link, increase the value of the repl-backlog-size parameter in the redis.conf file.

    • If some keys in the source database use an expiration policy, the destination database may have fewer keys than the source database. This is because expired keys may not be deleted from the source database immediately. Use the info command to check the key count.

    • Limitation on synchronizing data from a standalone Redis instance to a cluster Redis instance: Redis clusters only allow single-key operations within a single slot. If you perform a multi-key operation on the source database where the keys do not hash to the same slot, the following error occurs:

      CROSSSLOT Keys in request don't hash to the same slot

      We recommend performing only single-key operations during DTS synchronization to avoid task interruptions.

    • If the source is a Tair (Enterprise Edition) instance whose storage medium is persistent memory, ensure that the appendonly parameter is set to yes. For more information, see Steps.

    • If the source database is a child instance of a Tair (Enterprise Edition) instance that uses the Global Distributed Cache feature, DTS synchronizes data only from the selected child instance.

    Other limitations

    • If the source instance is a self-managed Redis, we recommend setting the replication timeout parameter repl-timeout to 600 seconds by using the command config set repl-timeout 600. If the source database is large, consider increasing the value of the repl-timeout parameter.

    • During synchronization, operations on the source or destination Redis instance can interrupt the task. These operations include scaling (such as adding or removing shards), instance configuration changes (such as increasing memory, changing specifications, or performing an availability zone migration), and changes to the connection endpoint or port. This happens because DTS can no longer obtain continuous log data or the correct connection information. If your task is interrupted for these reasons, clear the data from the destination instance and reconfigure the task to ensure data consistency.

    • If the source or destination is a self-managed Redis instance (the Access Method is not Alibaba Cloud Instance) and its connection endpoint changes during synchronization (for example, due to an instance migration or a failover), the synchronization task may experience retries, high latency, or failure, which can also lead to data inconsistency. Monitor the task status closely. If the DTS task shows retries, high latency, or other exceptions, reconfigure the task.

    • After a migration event (such as a failover) is triggered on the destination Redis instance, data might be written only to memory and not to the replica, which can result in data loss.

    • For best compatibility, ensure the source and destination databases run on the same version, or synchronize from an earlier version to a later one.

    • During full data initialization, DTS consumes read and write resources on both the source and destination databases, which may increase database load. Before you start data synchronization, evaluate the performance of your source and destination databases. Perform data synchronization during off-peak hours.

    • To prevent data inconsistency, do not write to the destination database from any source other than DTS during synchronization.

    • If the destination instance has a cluster architecture and one of its shards reaches its memory limit, or if the destination instance runs out of storage, the DTS task fails with an Out of Memory (OOM) error.

    • If the destination database runs out of memory and triggers data eviction, data inconsistency may occur. This is because the default eviction policy (maxmemory-policy) for Tair (Redis OSS-compatible) is volatile-lru. The sync task continues to run, but the data becomes inconsistent.

      To prevent this, you can set the eviction policy of the destination database to noeviction. If the destination database runs out of memory, data writes fail and the task fails. This prevents data loss due to eviction.

      Note

      For more information about data eviction policies, see Introduction to Redis data eviction policies.

    • If transparent data encryption (TDE) is enabled on the source or destination instance, DTS does not support data synchronization.

    • DTS may re-synchronize the full dataset if any of the following events occur. This process can cause data inconsistency.

      • A transient connection interruption occurs on the source or destination Redis instance, and resumable transmission fails.

      • A failover occurs on the source or destination Redis instance.

      • The connection endpoint of the source or destination Redis instance changes.

      • The synchronization objects of the DTS instance are changed.

    • If a Tair (Redis OSS-Compatible) instance has Transport Layer Security (TLS) encryption enabled, you must use an SSL-encrypted to connect to DTS (TLSv1.3 is not supported). Currently, you cannot connect a Tair (Redis OSS-Compatible) instance that has SSL enabled to DTS by using the Alibaba Cloud Instance method.

    • When you restart a synchronization task that includes both full and incremental data synchronization, DTS may re-run both the full and incremental tasks.

    • Restarting a synchronization instance may cause some commands to be re-executed. This re-execution can cause data inconsistency between the source and destination databases, especially if you use non-idempotent commands (such as INCRBY or LPUSH) or if the restart triggers a full data re-synchronization.

    • If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters.

      Note

      Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters.

    Billing

    Synchronization type

    Configuration fee

    Full data synchronization

    Free.

    Incremental data synchronization

    Charged. For details, see billing overview.

    Incremental synchronization commands

    Edition

    Commands

    Tair (Redis OSS-Compatible) Open-Source Edition

    • APPEND

    • BITOP, BLPOP, BRPOP, BRPOPLPUSH

    • DECR, DECRBY, DEL

    • EVAL, EVALSHA, EXEC, EXPIRE, EXPIREAT

    • GEOADD, GETSET

    • HDEL, HINCRBY, HINCRBYFLOAT, HMSET, HSET, HSETNX

    • INCR, INCRBY, INCRBYFLOAT

    • LINSERT, LPOP, LPUSH, LPUSHX, LREM, LSET, LTRIM

    • MOVE, MSET, MSETNX, MULTI

    • PERSIST, PEXPIRE, PEXPIREAT, PFADD, PFMERGE, PSETEX

    • RENAME, RENAMENX, RESTORE, RPOP, RPOPLPUSH, RPUSH, RPUSHX

    • SADD, SDIFFSTORE, SELECT, SET, SETBIT, SETEX, SETNX, SETRANGE, SINTERSTORE, SMOVE, SPOP, SREM, SUNIONSTORE

    • ZADD, ZINCRBY, ZINTERSTORE, ZREM, ZREMRANGEBYLEX, ZUNIONSTORE, ZREMRANGEBYRANK, ZREMRANGEBYSCORE

    • SWAPDB, UNLINK (Supported only when the source Redis instance is version 4.0)

    • XADD, XCLAIM, XDEL, XAUTOCLAIM, XGROUP CREATECONSUMER, XTRIM

    Tair (Redis OSS-Compatible) Enterprise Edition

    • APPEND

    • BITOP, BLPOP, BRPOP, BRPOPLPUSH

    • DECR, DECRBY, DEL

    • EVAL, EVALSHA, EXEC, EXPIRE, EXPIREAT

    • GEOADD, GETSET

    • HDEL, HINCRBY, HINCRBYFLOAT, HMSET, HSET, HSETNX

    • INCR, INCRBY, INCRBYFLOAT

    • LINSERT, LPOP, LPUSH, LPUSHX, LREM, LSET, LTRIM

    • MOVE, MSET, MSETNX, MULTI

    • PERSIST, PEXPIRE, PEXPIREAT, PFADD, PFMERGE, PSETEX

    • RENAME, RENAMENX, RPOP, RPOPLPUSH, RPUSH, RPUSHX

    • SADD, SDIFFSTORE, SELECT, SET, SETBIT, SETEX, SETNX, SETRANGE, SINTERSTORE, SMOVE, SPOP, SREM, SUNIONSTORE

    • UNLINK, ZADD, ZINCRBY, ZINTERSTORE, ZREM, ZREMRANGEBYLEX, ZUNIONSTORE, ZREMRANGEBYRANK, ZREMRANGEBYSCORE

    • XADD, XCLAIM, XDEL, XAUTOCLAIM, XGROUP CREATECONSUMER, XTRIM

    Note

    • The PUBLISH command is not supported.

    • For Lua scripts called by EVAL or EVALSHA, DTS cannot guarantee that the scripts are successfully executed during incremental data synchronization. This is because the destination does not explicitly return the execution results.

    • When retransmitting List data using sync or psync, DTS does not clear existing data on the destination. This may result in duplicate data.

    Preparation

    Log on to the Alibaba Cloud Management console with the primary account that owns the source Redis instance. Then, create a RAM role that grants the destination instance's primary account permission to access the source instance. For more information, see Configure RAM authorization for cross-account DTS tasks.

    Procedure

    Note

    This topic uses a cross-account source database to demonstrate how to configure a synchronization instance for a cross-account scenario. For more information, see Configure RAM authorization for cross-account DTS tasks.

    1. Log on with the primary account that owns the destination instance and go to the synchronization task list page.

      DTS console

      1. Log on to the DTS console.

      2. In the navigation pane on the left, click Data Synchronization.

      3. In the upper-left corner of the page, select the region where the synchronization instance is located.

      DMS console

      Note

      The actual steps may vary depending on the mode and layout of the DMS console. For more information, see Simple mode console and Customize the layout and style of the DMS console.

      1. Log on to the DMS console.

      2. In the top menu bar, choose Data + AI > DTS (DTS) > Data Synchronization.

      3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.

    2. Click Create Task to open the task configuration page.

    3. Configure the source and destination databases.

      Warning

      After you select the source and destination instances, review the Limits at the top of the page. Otherwise, the task may fail or data inconsistency may occur.

      Category

      Parameter

      Description

      N/A

      Task Name

      DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.

      Source Database

      Select Existing Connection

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

      • If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select Tair/Redis.

      Access Method

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the source Tair (Redis OSS-Compatible) instance resides.

      Replicate Data Across Alibaba Cloud Accounts

      Select Yes.

      Note

      This feature supports cross-site communication, allowing accounts on Alibaba Cloud (China) and Alibaba Cloud (International) to communicate with each other.

      Alibaba Cloud Account

      Enter the ID of the primary account that owns the source Tair (Redis OSS-Compatible) instance.

      Note

      For information about how to obtain the ID, see Obtain the ID of the primary account that owns the source database.

      RAM Role Name

      Enter the name of the RAM role that you created by using the primary account that owns the source database. Example: ram-for-dts.

      Note

      For information about how to create a RAM role, see Step 1: Create a RAM role.

      Instance ID

      Select the ID of the source Tair (Redis OSS-Compatible) instance.

      Authentication Method

      Select an authentication method based on your requirements. In this example, Password Login is selected.

      Note

      • Only Redis 6.0 and later support Account + Password Login.

      • If you select Secret-free login, make sure that password-free access is enabled for the Redis database. For information about how to enable password-free access for a Tair (Redis OSS-Compatible) instance, see Enable password-free access over a VPC.

      Database Password

      Enter the password for the account of the source Tair (Redis OSS-Compatible) instance. The account must have read permissions. If you forgot the password, you can reset it. For more information, see Modify or reset the password.

      • For the default account (named after the instance ID), enter only the password.

      • For a newly created account, use the format <custom_account>:<password>. Example: testaccount:Test1234.

      Note

      This parameter is optional. You can leave it blank if no password is set.

      Encryption

      Select Non-encrypted or SSL-encrypted based on your database instance requirements.

      Note

      If you are using a self-managed Redis instance (the Access Method is not Alibaba Cloud Instance) and you select SSL-encrypted, you must also upload a CA Certificate and enter the CA Key.

      Destination Database

      Select Existing Connection

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

      • If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select Tair/Redis.

      Access Method

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the destination Tair (Redis OSS-Compatible) instance resides.

      Replicate Data Across Alibaba Cloud Accounts

      In this example, the synchronization is for a cross-account source instance. Select No.

      Instance ID

      Select the ID of the destination Tair (Redis OSS-Compatible) instance.

      Authentication Method

      Select an authentication method based on your requirements. In this example, Password Login is selected.

      Note

      • Only Redis 6.0 and later support Account + Password Login.

      • If you select Secret-free login, make sure that password-free access is enabled for the Redis database. For information about how to enable password-free access for a Tair (Redis OSS-Compatible) instance, see Enable password-free access over a VPC.

      Database Password

      Enter the password for the account of the destination Tair (Redis OSS-Compatible) instance. The account must have read and write permissions. If you forgot the password, you can reset it. For more information, see Modify or reset the password.

      • For the default account (named after the instance ID), enter only the password.

      • For a newly created account, use the format <custom_account>:<password>. Example: testaccount:Test1234.

      Encryption

      Select Non-encrypted or SSL-encrypted based on your database instance requirements.

      Note

      If you are using a self-managed Redis instance (the Access Method is not Alibaba Cloud Instance) and you select SSL-encrypted, you must also upload a CA Certificate and enter the CA Key.

    4. After completing the configuration, click Test Connectivity and Proceed at the bottom of the page.

      Note

      • Ensure that you add the CIDR blocks of the DTS servers (either automatically or manually) to the security settings of both the source and destination databases to allow access. For more information, see Add the IP address whitelist of DTS servers.

      • If the source or destination is a self-managed database (i.e., the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

    5. Configure the task objects.

      1. On the Configure Objects page, specify the objects to synchronize.

        Parameter

        Description

        Synchronization Types

        DTS pre-selects either Incremental Data Synchronization or Full Data Synchronization + Incremental Data Synchronization. If only Incremental Data Synchronization is selected by default, select Full Data Synchronization as well. After the precheck, DTS performs a full data copy of the specified objects to the destination instance. This full copy serves as the baseline for subsequent incremental synchronization.

        Synchronization Topology

        Select One-way Synchronization.

        Note

        This parameter is available only when both the source and destination instances are Tair (Redis OSS-Compatible) Enterprise Edition.

        Processing Mode of Conflicting Tables

        • Precheck and Report Errors: Checks if the destination is empty. If the destination is empty, the precheck is successful. If the destination is not empty, an error is reported during the precheck, and the data synchronization job does not start.

        • Ignore Errors and Proceed: Skips the Check the existence of objects in the destination database. precheck.

          Warning

          If you select Ignore Errors and Proceed, source data overwrites destination data if the same key exists in both the source and destination. This may cause data loss in the destination. Select this option with caution.

        Source Objects

        In the Source Objects box, click the objects, and then click 向右 to move them to the Selected Objects box.

        Note

        Synchronization objects are selected at the database level. If you need to synchronize only the data for specific keys in the database, you can use the data filtering feature in the Selected Objects box.

        Selected Objects

        To specify a destination database (DB 0 to DB 255) to receive data or filter data by prefix, use the mapping or filtering feature. In the Selected Objects box, right-click the database to be synchronized and configure the settings in the Edit Schema dialog box. For more information, see Map object names and Specify filter conditions.

      2. Click Next: Advanced Settings.

        Parameter

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.

        Retry Time for Failed Connections

        If the connection to the source or destination database fails after the synchronization task starts, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails.

        Note

        • If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances.

        • DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.

        Retry Time for Other Issues

        If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails.

        Important

        The value of Retry Time for Other Issues must be less than that of Retry Time for Failed Connections.

        Enable Throttling for Full Data Synchronization

        During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s).

        Note

        This parameter is available only when Synchronization Types includes Full Data Synchronization.

        Enable Throttling for Incremental Data Synchronization

        You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).

        Extend Expiration Time of Destination Database Key

        Set an additional expiration time for keys from the source database when they are synchronized to the destination database. To ensure data consistency, we recommend setting an extended expiration time if you use any of the following commands.

        Note

        In distributed lock scenarios, this may delay lock releases.

        EXPIRE key seconds
PEXPIRE key milliseconds
EXPIREAT key timestamp
PEXPIREAT key timestampMs

        Environment Tag

        You can select an environment tag to identify the instance based on your requirements. This is not required for this example.

        Configure ETL

        Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values:

        Monitoring and Alerting

        Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts.

      3. Click Data Verification to configure a data verification task.

        To use the data verification feature, see Configure data verification.

    6. Save the task and perform a precheck.

      • To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.

      • If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

      Note

      • Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.

      • If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.

      • If the precheck generates warnings:

        • For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.

        • For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.

    7. Purchase the instance.

      1. When the Success Rate reaches 100%, click Next: Purchase Instance.

      2. On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

        Category

        Parameter

        Description

        New Instance Class

        Billing Method

        • Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks.

        • Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.

        Resource Group Settings

        The resource group to which the instance belongs. The default is default resource group. For more information, see What is Resource Management?.

        Instance Class

        DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.

        Subscription Duration

        In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years.

        Note

        This option appears only when the billing method is Subscription.

      3. Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.

      4. Click Purchase and Start, and then click OK in the OK dialog box.

        You can view the task progress on the Data Synchronization page.

        Note

        If you configure the DTS instance to perform both full and incremental synchronization (Synchronization Types includes both Full Data Synchronization and Incremental Data Synchronization), the task is displayed as Incremental Data Synchronization in the task list.