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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:Aug 25, 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

    • DTS inserts a key prefixed with DTS_REDIS_TIMESTAMP_HEARTBEAT into the source database to record update timestamps. For clusters, this key is inserted into each shard. The key is filtered during synchronization and expires after the task completes.

    • 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.

    • To ensure connection stability, increase the value of the repl-backlog-size parameter in the redis.conf file.

    • If some keys in the source database have an expiration policy, they may not be deleted immediately upon expiry. The key count in the destination (viewable with info) may be lower than in the source.

    • When synchronizing from a standalone to a cluster Redis instance, Redis clusters allow a single command to operate on only one slot. Multi-key operations on keys in different slots return the following error:

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

      To prevent task interruptions, perform only single-key operations during DTS synchronization.

    • If the source instance is a Tair (Enterprise Edition) instance whose Storage Medium is Persistent Memory, ensure that the appendonly parameter is set to yes as described in Steps.

    • If the source Redis instance uses extended modules such as RedisJSON, RediSearch, RedisBloom, RedisTimeSeries, RedisGraph, RedisAI, RedisGears, RedisCell, RediSQL, redis-tdigest, or RedisCompat, DTS cannot parse their RDB storage formats and the task fails.

    • If the source is a child instance of a Tair (Enterprise Edition) Global Distributed Cache, DTS can synchronize data only from the selected child instance. Data from other child instances in the group is not synchronized.

    Other limitations

    • For a self-managed Redis source, set repl-timeout to 600 seconds by running config set repl-timeout 600. Increase the repl-timeout value if the source contains a large amount of data.

    • Operations on the source or target Redis instance during synchronization, such as scaling, changing specifications, migrating availability zones, or changing the endpoint or port, can interrupt the task because DTS cannot obtain continuous log data or correct connection information. If this occurs, clear the synchronized data from the target before you reconfigure the task.

    • If the source or destination is a self-managed Redis (where Access Method is not Alibaba Cloud Instance) and its endpoint changes during synchronization (for example, due to a migration or primary/standby switchover), the task may experience retries, latency, or failures, and data inconsistency may occur. Monitor the task status and reconfigure it if abnormalities persist.

    • During an instance migration on a target Redis instance, such as a primary/standby switchover, data may be written only to memory without being replicated to the standby instance, which can cause data loss.

    • To ensure compatibility, use the same version for the source and destination databases or synchronize from an earlier version to a later one.

    • During initial full data synchronization, DTS consumes read and write resources on the source and destination, which may increase load. Evaluate database performance beforehand and synchronize during off-peak hours.

    • During DTS synchronization, do not write data to the destination database from any source other than DTS. Otherwise, data inconsistency between the source and destination databases will result.

    • If the destination instance is a cluster and one of its shards reaches its memory limit, or if the destination instance runs out of storage space, the DTS task fails due to an out-of-memory (OOM) error.

    • If the destination runs out of memory, data eviction may cause inconsistency between the source and destination. The default maxmemory-policy for Tair (Redis OSS-Compatible) is volatile-lru, which does not affect task operation but may evict data.

      Set the destination eviction policy to noeviction to prevent data loss. With this policy, write operations fail and the task stops when memory is exhausted, but no data is evicted.

    • DTS does not support synchronization if Transparent Data Encryption (TDE) is enabled on the source or destination instance.

    • Full data may be re-synchronized to the destination and cause data inconsistency under the following conditions:

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

      • A primary/standby switchover or a failover occurs on the source or destination Redis.

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

      • The synchronized objects of the DTS instance are modified.

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

    • Restarting a synchronization instance that includes both full and incremental tasks may cause DTS to rerun both.

    • Restarting a synchronization instance may cause commands to execute more than once, leading to data inconsistency if non-idempotent commands such as INCRBY and LPUSH exist, or if full data re-synchronization is triggered.

    • 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

    Type

    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 synchronized.

    • For Lua scripts invoked with EVAL or EVALSHA, DTS cannot guarantee that the scripts are successfully executed on the destination during incremental data synchronization. This is because the destination does not explicitly return an execution result.

    • For List data types, DTS does not clear existing data on the destination when retransmitting data with sync or psync. 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 DMS console layout and style.

      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 Certificate Password.

      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 Certificate Password.

    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

        You can select objects only at the database level. To synchronize data for specific keys within a database, use the data filtering feature in the Selected Objects pane.

        Selected Objects

        To specify a destination database (DB 0 to DB 255) or filter data by prefix, use the mapping or filtering features. In the Selected Objects pane, right-click the database to synchronize, and then configure the settings in the Edit Schema dialog box that appears. 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 your DTS instance is configured for both full and incremental data synchronization (meaning Synchronization Types includes both Full Data Synchronization and Incremental Data Synchronization), the task appears as Incremental Data Synchronization in the synchronization task list.