This topic describes how to migrate data between ApsaraDB for Redis instances by using Data Transmission Service (DTS).
Prerequisites
- The source and destination ApsaraDB for Redis instances are created. Note
- For more information about how to create an ApsaraDB for Redis instance, see Step 1: Create an ApsaraDB for Redis instance.
- For more information about the supported database engine versions, see Overview of data migration scenarios.
- 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.
Limits
Category | Migration description |
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Limits on the source database |
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Other limits |
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Special cases | If the source database is a self-managed Redis database, take note of the following limits:
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Migration types
Migration type | Description |
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Full data migration | DTS migrates the existing data of objects from the source database to the destination database. |
Incremental data migration | After full data migration is complete, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting services of self-managed applications during data migration. |
Commands that are supported by incremental data migration
- 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
Procedure
- Go to the Data Migration Tasks page.
- Log on to the Data Management (DMS) console.
- In the top navigation bar, click DTS.
- In the left-side navigation pane, choose .
Note- Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Configure the DMS console based on your business requirements.
- You can also go to the Data Migration Tasks page of the new DTS console.
- 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.
- Click Create Task. On the page that appears, configure the source and destination databases.
Section Parameter Description N/A Task Name The name of the task. DTS automatically generates a task name. We recommend that you specify an informative name 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 choose whether to use an existing instance based on your business requirements.- If you use an existing instance, DTS automatically applies the parameter settings of the source database.
- If you do not use an existing instance, you must configure the parameters for the database.
Database Type Select Tair/Redis. Access Method Select Alibaba Cloud Instance. In this example, the source and destination databases are ApsaraDB for Redis instances. You can also follow the procedure to configure data migration tasks for other types of databases. Instance Region The region where the source ApsaraDB for Redis instance resides. Replicate Data Across Alibaba Cloud Accounts Specifies whether data is replicated across Alibaba Cloud accounts. In this example, No is selected. Instance ID The ID of the source ApsaraDB for Redis instance. 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 can enter only the password.
- If you create a custom account, you must specify the password in the
<Custom account>:<Password>
format. Example: testaccount:Test1234.
Note This parameter is optional and can be left empty if no database password is set.Destination Database Select an existing DMS database instance The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements.- If you use an existing instance, DTS automatically applies the parameter settings of the instance.
- If you do not use an existing instance, you must configure the parameters for the database.
Database Type Select Tair/Redis. Access Method Select Alibaba Cloud Instance. Instance Region The region where 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 can enter only the password.
- If you create a custom account, you must specify the password in the
<Custom account>:<Password>
format. Example: testaccount:Test1234.
- In the lower part of the page, click Test Connectivity and Proceed.Warning If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database or an 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: enhance the security of your username and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
- Configure objects to migrate and advanced settings.
- Basic Settings
Parameter Description Migration Type Select Full Data Migration and Incremental Data Migration. For more information, see Migration types.
Processing Mode of Conflicting Tables Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain identical table names, 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 for identical table names in the source and destination databases. Warning If you select Ignore Errors and Proceed, data inconsistency may occur, and your business may be exposed to potential risks.
- If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database.
- If the source and destination databases have different schemas, only some columns are migrated or the data migration task fails. 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 databases as the objects to be migrated. Keys cannot be selected as objects to be migrated.Selected Objects - The objects that you select to be migrated. In this scenario, you cannot rename the objects.
- In the Selected Objects section, right-click an object. In the dialog box that appears, select the commands that you want to migrate. For more information, see Commands that are supported by incremental data migration.
- Advanced Settings
Parameter Description Set Alerts Specifies whether to set alerts for the data migration task. If the task fails or the migration latency exceeds the threshold, the alert contacts will receive notifications. Valid values:- No: does not set alerts.
- Yes: sets alerts. If you select Yes, you must also set the alert threshold and alert contacts. For more information, see Configure monitoring and alerting when you create a DTS task.
Retry Time for Failed Connections The retry time range for failed connections. If the data migration task fails, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 120. We recommend that you set the 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 migration task. Otherwise, the data migration task fails.Note- If an instance serves as the source database of multiple data migration tasks, the less value of this parameter that is set for the instance 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.
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 configure 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.
- Basic Settings
- In the lower part of the page, click Next: Save Task Settings and Precheck. 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 causes, run a precheck again.
- 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 issues. 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.
- Wait until the Success Rate value becomes 100%. Then, click Next: Purchase Instance.
- On the Purchase Instance page, specify the Instance Class parameter for the data migration instance. The following table describes the parameter.
Section Parameter Description Parameters Instance Class DTS provides several 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.
- Read and select the check box to agree to Data Transmission Service (Pay-as-you-go) Service Terms.
- Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.