Data Transmission Service：Migrate data between ApsaraDB for Redis instances across Alibaba Cloud accounts

Prerequisites

• The available storage space of the destination ApsaraDB for Redis instance is larger than the total size of the data in the source ApsaraDB for Redis instance.

• If the source ApsaraDB for Redis instance is a Community Edition instance, the engine version is 4.0 or 5.0. If the source ApsaraDB for Redis instance is an Enhanced Edition (Tair) instance, the engine version is 5.0.

Supported source and destination databases

The following table describes the supported databases when you perform data migration between ApsaraDB for Redis instances across Alibaba Cloud accounts.

Limits

Migration types

Commands that can be incrementally migrated

• APPEND

• BITOP, BLPOP, BRPOP, and BRPOPLPUSH

• DECR, DECRBY, and DEL

• EVAL, EVALSHA, EXEC, EXPIRE, and EXPIREAT

• FLUSHALL and FLUSHDB

• 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, PSETEX, and PUBLISH

• 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

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

Preparations

Use the Alibaba Cloud account that owns the source ApsaraDB for Redis instance to log on to the Alibaba Cloud Management console. Create a RAM role and set the Alibaba Cloud account that owns the destination Redis instance as the trusted account. Then, authorize the RAM role to access the cloud resources of source Alibaba Cloud account. For more information, see Configure RAM authorization for cross-account DTS tasks.

Procedure

1. Use the Alibaba Cloud account that owns the destination ApsaraDB for Redis instance to log on to the Data Management (DMS) console and go to the Data Migration Tasks page.

   1. Log on to the DMS console.

   2. In the top navigation bar, move the pointer over DTS.

   3. Choose DTS (DTS) > Data Migration.

   Note

   • The actual steps that you need to perform 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 Migration Tasks page of the new DTS console.

2. From the drop-down list next to Data Migration Tasks, select the region in which the data migration instance resides.

   Note

   If you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.

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

   Warning

   After you configure the source and destination databases, we recommend that you read the limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

   Section	Parameter	Description
   N/A	Task Name	The name of the task. DTS automatically assigns a name to the task. 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 an existing DMS database instance	The database instance that you want to use. You can determine whether to select an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the instance. If you do not select an existing instance, you must configure parameters for the source database.
   	Database Type	The type of the source database. Select ApsaraDB for Redis Enhanced Edition (Tair).
   	Access Method	The access method of the source database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the source ApsaraDB for Redis instance resides.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to migrate data across Alibaba Cloud accounts. In this example, Yes is selected.
   	Alibaba Cloud Account	The ID of the Alibaba Cloud account that owns the source ApsaraDB for Redis instance. Note To obtain the ID of the Alibaba Cloud account that owns the source ApsaraDB for Redis instance, log on to the Account Management console by using this account. The account ID is displayed on the Basic Information page.
   	RAM Role Name	The name of the RAM role that you created by following the instructions in the Preparations section of this topic.
   	Database Password	The database password of the source ApsaraDB for Redis instance. The database account that corresponds to the password must have the read permissions. If you forget the password, you can reset the password. For more information, see Change or reset the password. If you use the default account whose username is the same as the instance ID, you need to enter only the password. If you use a custom account, specify the password in the <Custom account username>:<Password> format. Example: testaccount:Test1234. Note This parameter is optional and can be left empty if no database password is set for the source ApsaraDB for Redis database.
   Destination Database	Select an existing DMS database instance	The database instance that you want to use. You can determine whether to select an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the instance. If you do not select an existing instance, you must configure parameters for the destination database.
   	Database Type	The type of the destination database. Select ApsaraDB for Redis Enhanced Edition (Tair).
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination ApsaraDB for Redis instance resides.
   	Instance ID	The ID of the destination ApsaraDB for Redis instance.
   	Database Password	The database password of the destination ApsaraDB for Redis instance. The database account that corresponds to the password must have the read permissions. If you forget the password, you can reset the password. For more information, see Change or reset the password. If you use the default account whose username is the same as the instance ID, you need to enter only the password. If you use a custom account, specify the password in the <Custom account username>:<Password> format. Example: testaccount:Test1234.

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 IP address 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 make sure that the ECS instance can access the database. If the self-managed database is hosted on multiple ECS instances, you must manually add the CIDR blocks of DTS servers to the security group rules of each ECS instance. 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 IP address whitelist of the database to allow DTS to access the database. For more information, see the "CIDR blocks of DTS servers" section of the Add the CIDR blocks of DTS servers topic.

   Warning

   If the public CIDR blocks of DTS servers are automatically or manually added to the IP address whitelist of a database instance or to the security group rules of an ECS instance, security risks may arise. Therefore, before you use DTS to migrate 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 account and password, limiting the ports that are exposed, authenticating API calls, regularly checking the IP address whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, and connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

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

   Parameter	Description
   Migration Types	We recommend that you select both Full Data Migration and Incremental Data Migration. If you do not have the permissions to run the SYNC or PSYNC command on the source database, select Full Data Migration. For more information, see the Migration types section of this topic.
   Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database is empty. If the destination database is empty, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started. Ignore Errors and Proceed: skips the precheck on whether the destination database is empty. Warning If you select Ignore Errors and Proceed, the data in the source database overwrites the data in the destination database that has the same keys as the source data. This may cause data loss in the destination database. Proceed with caution.
   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 the objects to be migrated. You cannot select keys as the objects to be migrated.
   Selected Objects	If you want to select a database to which data is migrated from DB 0 to DB 255 or filter the data to be migrated by prefix, you can use the object name mapping feature or the filtering feature. In the Selected Objects section, right-click the database that you want to migrate. In the Edit Schema dialog box, configure the parameters. For more information, see Map object names and Set filter conditions. Note You cannot map multiple object names at a time.

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

   • Data Verification Settings

     For more information about how to configure the data verification feature, see Configure data verification.

   • Advanced Settings

     Parameter	Description
     Select the dedicated cluster used to schedule the task	By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. You can also purchase and specify a dedicated cluster of the required specifications to run the data migration task. For more information, see What is a DTS dedicated cluster.
     Set Alerts	Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts will receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. If you select Yes, you must also specify the alert threshold and alert contacts. For more information, see Configure monitoring and alerting.
     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 migration task is started, DTS immediately retries a connection within the retry time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later 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.
     The wait time before a retry when other issues occur in the source and destination databases.	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry 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 retry time range, DTS resumes the data migration task. Otherwise, the data migration 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 Connections parameter.
     Enable Throttling for Full Data Migration	Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server. Note This parameter is displayed only when Full Data Migration is selected as Migration Types.
     Enable Throttling for Incremental Data Migration	Specifies whether to enable throttling for incremental data migration. If you select Yes, you can configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters based on your business requirements. This reduces the loads of the destination database server. Note This parameter is available only if you select Full Data Migration and Incremental Data Migration as the migration types.Migration Types
     Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is selected.
     Extend Expiration Time of Destination Database Key	The extended time period for keys migrated 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 migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.

   • If the task fails to pass the precheck, click View Details next to each failed item. After you troubleshoot the issues based on the error message, you can run a precheck again.

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

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

     • If the 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 Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

   Section	Parameter	Description
   New Instance Class	Resource Group	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
   	Instance Class	DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Specifications of data migration instances.

10. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

11. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.