Data Transmission Service：Synchronize data from a self-managed Redis database hosted on an ECS instance to a Tair instance

Prerequisites

• A self-managed Redis database and a Tair instance are created. For more information about how to create a Tair instance, see Step 1: Create a Tair instance.

  Note

  • DTS supports only Tair instances for which the direct connection mode is enabled.

  • DTS also supports one-way synchronization between Tair instances. You can refer to the configuration method described in this topic to configure one-way synchronization between the Tair instances.

• The version of the self-managed Redis database is 2.8, 3.0, 3.2, 4.0, 5.0, or 6.0.

• The available storage space of the destination Tair instance is larger than the total size of the data in the source self-managed Redis database.

• If the source Redis database is deployed in a cluster architecture, all nodes of the Redis cluster support the PSYNC command and share the same password.

• The timeout period for data replication between the master and replica nodes in the source instance is specified by the repl-timeout parameter. By default, this parameter is set to 60 seconds. We recommend that you run the config set repl-timeout 600 command to set this parameter to 600 seconds. If the source instance stores a large amount of data, you can increase the value of the repl-timeout parameter based on your business requirements.

Limits

Billing

Supported synchronization topologies

• One-way one-to-one synchronization

• One-way one-to-many synchronization

• One-way cascade synchronization

For more information, see Synchronization topologies.

Operations that can be synchronized

• APPEND

• BITOP, BLPOP, BRPOP, and BRPOPLPUSH

• DECR, DECRBY, and DEL

• EVAL, EVALSHA, EXEC, EXPIRE, and EXPIREAT

• GEOADD and GETSET

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

• INCR, INCRBY, and INCRBYFLOAT

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

• MOVE, MSET, MSETNX, and MULTI

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

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

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

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

• SWAPDB and UNLINK (supported only if the engine version of the source instance is 4.0)

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

Procedure

1. Go to the Data Synchronization Tasks page.

   1. Log on to the Data Management (DMS) console.

   2. In the top navigation bar, click DTS.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.

   Note

   • Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.

   • You can also go to the Data Synchronization Tasks page of the new DTS console.

2. On the right side of Data Synchronization Tasks, select the region in which the data synchronization instance resides.

   Note

   If you use the new DTS console, you must select the region in which the data synchronization instance resides in the top navigation bar.

3. Click Create Task. In the Create Data Synchronization Task wizard, configure the source and destination databases. The following table describes the parameters.

   Section	Parameter	Description
   N/A	Task Name	The name of the DTS task. DTS automatically generates a task name. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Select a DMS database instance	The database that you want to use. You can choose whether to use an existing database based on your business requirements. If you select an existing database, DTS automatically populates the parameters for the database. If you do not select an existing database, you must configure the following database information.
   	Database Type	The type of the source database. Select Tair/Redis.
   	Access Method	The access method of the source database. Select Self-managed Database on ECS.
   	Instance Region	The region in which the source Redis database resides.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to synchronize data across Alibaba Cloud accounts. In this example, No is selected.
   	ECS Instance ID	The ID of the ECS instance that hosts the source Redis database. Note If the source Redis database is deployed in a cluster architecture, select the ID of the ECS instance in which a master node resides.
   	Instance Mode	The architecture in which the source Redis database is deployed. Select Standalone or Cluster.
   	Port number	The service port number of the source Redis database. Default value: 6379. Note If the source Redis database is deployed in a cluster architecture, enter the service port number of a master node.
   	Database Password	The password of the source Redis database. Note This parameter is optional and can be left empty if no password is set. The database password is in the <user>:<password> format. For example, if the username of the account that you use to log on to the source Redis database is admin and the password is Rp829dlwa, the database password is admin:Rp829dlwa.
   Destination Database	Select a DMS database instance	The database that you want to use. You can choose whether to use an existing database based on your business requirements. If you select an existing database, DTS automatically populates the parameters for the database. If you do not select an existing database, you must configure the following database information.
   	Database Type	The type of the destination instance. Select Tair/Redis.
   	Access Method	The access method of the destination instance. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination Tair instance resides.
   	Instance ID	The ID of the destination Tair instance.
   	Database Password	The password of the destination Tair instance. Note The database password is in the <user>:<password> format. For example, if the username of the account that you use to log on to the destination Tair instance is admin and the password is Rp829dlwa, the database password is admin:Rp829dlwa.

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

   If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must ensure that the ECS instance can access the database. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information, see Add the CIDR blocks of DTS servers.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

5. Configure the objects to be synchronized and advanced settings.

   Parameter	Description
   Synchronization Types	The synchronization type. By default, Full Data Synchronization + Incremental Data Synchronization is selected.
   Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether data exists in the destination database. If no data exists in the destination database, the precheck is passed. If data exists in the destination database, an error is returned during the precheck, and the data synchronization task cannot be started. Ignore Errors and Proceed: skips the Check the existence of objects in the destination database. check item. Warning If you select Ignore Errors and Proceed, data loss may occur in the destination database because data records in the source database overwrite the data records that have the same keys in the destination database. Proceed with caution.
   Use Slave Node	If the Instance Mode parameter of the source self-managed Redis database is set to Cluster, you can pull data from the master or slave nodes.
   Source Objects	Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section. Note You can select only databases as objects to be synchronized. Keys cannot be selected as objects to be synchronized.
   Selected Objects	The objects that you select to synchronize. In this scenario, you cannot rename the objects.

6. Click Next: Advanced Settings to configure advanced settings.

   • Data Verification Settings

     For more information about how to enable data verification, see Configure a data verification task.

   • Advanced settings

     Parameter	Description
     Monitoring and Alerting	Specifies whether to configure alerting for the data synchronization task. If the task fails or the synchronization latency exceeds the specified threshold, alert contacts will receive notifications. Valid values: No: does not enable alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see the "Configure monitoring and alerting when you create a DTS task" section of the Configure monitoring and alerting topic.
     Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data synchronization task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set this parameter to a value greater than 30. 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 you specify different retry time ranges for multiple data synchronization tasks that have the same source or destination database, the shortest retry time range 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 requirements. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
     Retry Time for Other Issues	The retry time range for other issues. For example, if the DDL or DML operations fail to be performed after the data synchronization task is started, DTS immediately retries the operations within the time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Important The value of the The wait time before a retry when other issues occur in the source and destination databases parameter must be smaller than the value of the Retry Time for Failed Connection parameter.
     Enable Throttling for Incremental Data Migration	The load on the destination instance may increase when DTS synchronizes incremental data to the destination instance. You can configure throttling thresholds for the number of rows and the amount of data that can be synchronized per second during incremental data synchronization based on your business requirements. This helps reduce the load on the destination instance.
     Extend Expiration Time of Destination Database Key	The extended time period for keys synchronized from the source database to the destination instance to remain valid. Unit: seconds. If specific commands are used, such as the following commands, we recommend that you set the parameter to 600 to ensure data consistency. EXPIRE key seconds PEXPIRE key milliseconds EXPIREAT key timestamp PEXPIREAT key timestampMs
     Configure ETL	Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.

7. Save the task settings and run a precheck.

   • To view the parameters to be specified when you call the relevant API operation to configure the DTS task, move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters.

   • If you do not need to view or have viewed the parameters, click Next: Save Task Settings and Precheck in the lower part of the page.

   Note

   • Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization task only after the task passes the precheck.

   • If the data synchronization task fails the precheck, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, rerun the precheck.

   • If an alert is triggered for an item during the precheck:

     • If an alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issue. Then, run a precheck again.

     • If an alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur, and your business may be exposed to potential risks.

8. Wait until the Success Rate becomes 100%. Then, click Next: Purchase Instance.

9. On the buy page, configure the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.

   Section	Parameter	Description
   New Instance Class	Billing Method	Subscription: You pay for a subscription when you create a data synchronization instance. The subscription billing method is more cost-effective than the pay-as-you-go billing method for long-term use. Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. The pay-as-you-go billing method is suitable for short-term use. If you no longer require a pay-as-you-go data synchronization instance, you can release the instance to reduce costs.
   	Resource Group Settings	The resource group to which the data synchronization instance belongs. Default value: default resource group. For more information, see What is Resource Management?
   	Instance Class	DTS provides instance classes that vary in synchronization speed. You can select an instance class based on your business requirements. For more information, see Instance classes of data synchronization instances.
   	Subscription Duration	If you select the subscription billing method, specify the subscription duration and the number of data synchronization instances that you want to create. The subscription duration can be one to nine months, one year, two years, three years, or five years. Note This parameter is available only if you select the Subscription billing method.

10. Read and select Data Transmission Service (Pay-as-you-go) Service Terms.

11. Click Buy and Start. In the dialog box that appears, click OK.

    You can view the progress of the task in the task list.