How to synchronize RDS SQL Server to RDS MySQL-Data Transmission Service(DTS)-阿里云帮助中心

Prerequisites

An RDS SQL Server instance. For supported versions, see Synchronization overview. To create one, see Quickly create and use an RDS SQL Server instance.
You have created a destination ApsaraDB RDS for MySQL instance. For more information, see Create an ApsaraDB RDS for MySQL instance.
The destination ApsaraDB RDS for MySQL instance must have more storage space than the source ApsaraDB RDS for SQL Server instance.
We recommend splitting a synchronization task into multiple tasks if the source instance meets any of the following conditions:
- The instance contains more than 10 databases.
- Log backups occur on a single database more than once per hour.
- More than 100 DDL operations occur on a single database per hour.
- Log volume for a single database exceeds 20 MB/s
- More than 1,000 tables require Change Data Capture (CDC) to be enabled.

Limitations

Note

During schema synchronization, DTS synchronizes foreign keys from the source database to the destination database.
During full data synchronization and incremental data synchronization, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. Data inconsistency may occur if cascade update or delete operations are performed on the source database while the task is running.

Type	Description
Source database limitations	Tables to be synchronized must have a primary key or a UNIQUE constraint, and the fields must be unique. Otherwise, duplicate data may appear in the destination database. If you synchronize data at the table level, need to edit objects such as mapping column names, and the number of tables in a single task exceeds 5,000, split the tables into multiple tasks. You can also configure a task to synchronize the entire database. Otherwise, an error may be reported after you submit the task. A single sync task supports a maximum of 10 databases. If you exceed this limit, you risk stability and performance issues. In this case, split the tables and configure them in multiple tasks. When you configure a task to synchronize specific objects to the same destination database, you cannot select objects that have the same table name but different schema names. DTS uses the `fn_log` function to get logs from the source database. This function has performance bottlenecks. Do not clear the source database logs too early, or the task may fail. Data logs: Data logs must be enabled. The backup mode must be set to Full, and a full physical backup must have been successfully performed. For incremental synchronization tasks, DTS requires the source database to retain data logs for more than 24 hours. For tasks that include both full and incremental synchronization, DTS requires the source database to retain data logs for at least 7 days. After the full synchronization is complete, you can change the log retention period to more than 24 hours. If the retention period is too short, the DTS task may fail because it cannot get the data logs. In extreme cases, this can cause data inconsistency or data loss. Issues caused by setting a log retention period shorter than required by DTS are not covered by the DTS Service-Level Agreement (SLA). If Change Data Capture (CDC) needs to be enabled for tables in the source database, the following conditions must be met. Otherwise, the precheck fails. The value of the `srvname` field in the `sys.sysservers` view must be the same as the return value of the `SERVERPROPERTY` function. If the source database is a self-managed SQL Server instance, the database owner must be `sa`. If the source database is an RDS for SQL Server instance, the database owner must be `sqlsa`. If the source database is Enterprise Edition, it must be SQL Server 2008 or later. If the source database is Standard Edition, it must be SQL Server 2016 SP1 or later. If the source database is SQL Server 2017 (Standard or Enterprise Edition), upgrade the version. If the source instance is a read-only instance, DDL operations cannot be synchronized. If the source database is an Azure SQL Database, a single sync instance can synchronize only one database. If the source database is an RDS for SQL Server instance, ensure that the Transparent Data Encryption (TDE) feature is disabled to ensure the stability of the sync instance. For more information, see Disable TDE. In hybrid log parsing mode, you cannot consecutively run multiple operations to add or drop columns in the source database within a 10-minute interval. For example, running the following SQL statements consecutively causes the task to report an error. `ALTER TABLE test_table DROP COLUMN Flag; ALTER TABLE test_table ADD Remark nvarchar(50) not null default('');` If you use the `sp_rename` command to modify the names of objects, such as stored procedures, in the source database before a schema synchronization task runs, the task may produce unexpected results or fail. Note We recommend using the `ALTER` command to rename database objects. Do not run DDL operations that change database or table schemas during schema synchronization or full synchronization. Otherwise, the synchronization task fails. Note During full synchronization, DTS queries the source database. This creates metadata locks that may block DDL operations on the source database. If the source database is a web-based RDS SQL Server, you must set SQL Server Incremental Synchronization Mode to Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported) when you configure the task. We recommend that you keep the `READ_COMMITTED_SNAPSHOT` transaction processing mode parameter of the source database enabled while a full data sync task is running. This prevents shared locks from affecting data writes. Otherwise, issues such as data inconsistency or instance failures may occur. Such issues are not covered by the DTS Service-Level Agreement (SLA).
Other restrictions	Requirements for synchronization objects: Initial schema synchronization is supported for databases, schemas, and tables. Data of the following data types cannot be synchronized: CURSOR, ROWVERSION, SQL_VARIANT, HIERARCHYID, POLYGON, GEOMETRY, GEOGRAPHY, and user-defined types created with the `CREATE TYPE` command. The following objects cannot be synchronized: PROCEDURE, FUNCTION, TRIGGER, DATATYPE, SYNONYM, CATALOG, PLAN_GUIDE, and SEQUENCE. If your data includes four-byte characters—such as rare Chinese characters or emojis—the destination database and table must use the utf8mb4 charset. Note If you use DTS to synchronize table schemas, set the `character_set_server` parameter at the instance level in the destination database to utf8mb4. If you set SQL Server Incremental Synchronization Mode to Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported) in the Configure Objects stage, the tables to be synchronized must have a clustered index that contains the primary key column. Synchronization of heap tables, tables without a primary key, compressed tables, tables with computed columns, or tables with sparse columns is not supported. These restrictions do not apply in the hybrid log parsing mode. Note For information about how to view table information, see How to view information about heap tables, tables without a primary key, compressed tables, tables with computed columns, and tables with sparse columns in SQL Server. In the Configure Objects stage, if you set SQL Server Incremental Synchronization Mode to Log-based Parsing for Non-heap Tables and CDC-based Incremental Synchronization for Heap Tables (Hybrid Log-based Parsing), the following limitations also apply: The incremental synchronization of DTS depends on the CDC component. Ensure that the CDC job in the source database is running correctly. Otherwise, the DTS task will fail. By default, the incremental data stored by the CDC component is retained for 3 days. Adjust the retention period as needed using the `exec console.sys.sp_cdc_change_job @job_type = 'cleanup', @retention= <time>;` command. Note `<time>` specifies the time in minutes. If the average number of daily incremental change SQL statements for a single table in the source database exceeds 10 million, set `<time>` to 1440. The prerequisite module for a DTS incremental synchronization task enables CDC at the database and table levels in the source database. During this process, the source database may be briefly locked due to limitations of the SQL Server database kernel. In a single sync task, do not enable CDC for more than 1,000 tables. Otherwise, the task may experience latency or become unstable. If you set SQL Server Incremental Synchronization Mode to Polling and querying CDC instances for incremental synchronization in the Configure Objects stage, the following limitations also apply: The source database account used by the DTS instance must have the permission to enable CDC. Enabling database-level CDC requires an account with the sysadmin role permission, and enabling table-level CDC requires a privileged account. Note The privileged account (server administrator) provided in the Azure SQL Database console meets the requirements. For databases that use the vCore-based purchasing model, all specifications support enabling CDC. For databases that use the DTU-based purchasing model, the specification must be S3 or higher to support enabling CDC. The privileged account for Amazon RDS for SQL Server meets the requirements and supports enabling database-level CDC for stored procedures. CDC cannot be enabled for tables with clustered columnstore indexes. The prerequisite module for a DTS incremental synchronization task enables CDC at the database and table levels in the source database. During this process, the source database may be briefly locked due to limitations of the SQL Server database kernel. DTS polls the CDC instance of each table in the source database to get incremental data. Therefore, do not synchronize more than 1,000 tables from the source database. Otherwise, the task may experience latency or become unstable. By default, the incremental data stored by the CDC component is retained for 3 days. Adjust the retention period as needed using the `exec console.sys.sp_cdc_change_job @job_type = 'cleanup', @retention= <time>;` command. Note `<time>` specifies the time in minutes. If the average number of daily incremental change SQL statements for a single table in the source database exceeds 10 million, set `<time>` to 1440. Running add or drop column operations consecutively (more than two add or drop DDL operations within one minute) is not supported. Otherwise, the task may fail. Do not modify the CDC instance in the source database. Otherwise, the task may fail or data may be lost. Complex DDL operations are not supported for synchronization. To ensure accurate latency for incremental data synchronization, DTS performs the following actions: In the "parse source logs for incremental synchronization" mode, DTS creates the dts_cdc_sync_ddl trigger, the dts_sync_progress heartbeat table, and the dts_cdc_ddl_history DDL storage table in the source database. In hybrid incremental synchronization mode, DTS creates the dts_cdc_sync_ddl trigger, the dts_sync_progress heartbeat table, and the dts_cdc_ddl_history DDL storage table, and also enables database-level CDC and CDC for some tables. The data change volume for tables with CDC enabled in the source database should not exceed 1,000 records per second (RPS). Evaluate the performance of the source and destination databases before you synchronize data. Synchronize data during off-peak hours. Otherwise, the initial full data synchronization consumes read and write resources on both databases, which may increase the database load. Initial full synchronization runs concurrent INSERT operations, which causes table fragmentation in the destination database. As a result, the tablespace of the destination instance is larger than that of the source instance after the initial full synchronization is complete. During DTS synchronization, do not write data to the destination database from any source other than DTS. This can cause data inconsistency between the source and destination databases. For example, if you use DMS to perform online DDL operations while data is being written to the destination database from another source, data loss may occur in the destination database. Reindexing is not supported for a sync instance. This operation can cause the task to fail or even lead to data loss. Note Changes related to the primary key are not supported for tables with CDC enabled. If the number of tables with CDC enabled in a single sync task is greater than the value set for The maximum number of tables for which CDC is enabled that DTS supports., the precheck will fail. If a single field in a table with CDC enabled needs to store more than 64 KB of data, you must run the `exec sp_configure 'max text repl size', -1;` command in advance to adjust the configuration of the source database. Note By default, a CDC job can process a maximum of 64 KB for a single field. If a DDL statement fails to be written to the destination database, the DTS task continues to run. Check the task logs for the failed DDL statement. For more information about how to view task logs, see Query task logs. If you write columns with names that differ only in case to the same table in the destination MySQL database, unexpected results may occur because MySQL column names are case-insensitive. After data synchronization completes (the instance's Status is Completed), you should use the `ANALYZE TABLE <table_name>` command to confirm that all data is written to the target table. For example, after the HA failover mechanism is triggered in the target MySQL database, data might be written only to memory, which can cause data loss. To use the feature to modify synchronized objects, you cannot remove a database. If multiple sync instances use the same SQL Server database as the source, their incremental data ingestion modules are independent of each other. 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. SQL Server is a commercial, closed-source database. Its log format has characteristics that can cause unavoidable issues when DTS performs incremental CDC and parsing. Before you use DTS for incremental or migration synchronization from a SQL Server source in a production environment, perform a comprehensive proof of concept (POC). Your POC should cover all business change types, table schema adjustments, and peak-hour stress tests. The SQL Server log format can be unpredictable. To ensure that DTS runs efficiently and stably, make sure your production business logic is consistent with what you tested in the POC.
Special cases	If the source instance is an RDS for SQL Server instance, DTS creates a `rdsdt_dtsacct` account in the source instance for data synchronization. Do not delete this account or change its password while the task is running. Otherwise, the task may fail. For more information, see System accounts.

Billing

Synchronization type	Pricing
Schema synchronization and full data synchronization	Free of charge.
Incremental data synchronization	Charged. For more information, see Billing overview.

Synchronization topologies

One-way one-to-one synchronization
One-way one-to-many synchronization
One-way many-to-one synchronization

For an introduction to these synchronization topologies and their usage, see Data synchronization topologies.

Supported SQL operations

Operation type	SQL statement
DML	INSERT, UPDATE, and DELETE Note `UPDATE` statements that only update large object (LOB) columns are not supported.
DDL	CREATE TABLE ALTER TABLE (ADD COLUMN and DROP COLUMN only) DROP TABLE CREATE INDEX and DROP INDEX Note DDL operations that contain user-defined types are not supported. Online DDL operations are not supported. Transactional DDL operations are not supported. For example, adding multiple columns in a single SQL statement or mixing DDL and DML operations can cause data loss. DDL operations that use a reserved keyword as an attribute name are not supported. DDL operations executed by a system stored procedure are not supported. `TRUNCATE TABLE` operations are not supported. Partitioned tables and tables defined with functions are not supported.

Required permissions for database accounts

Database instance	Required permissions	Actions
Source ApsaraDB RDS for SQL Server instance	Owner permissions on the objects to be synchronized.	Create an account and Modify the permissions of an account.
Destination ApsaraDB RDS for MySQL instance	Read and write permissions on the destination database.	Create accounts and databases and Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance.

Procedure

Go to the data synchronization task list page in the destination region. You can do this in one of two ways.
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.
Click Create Task to open the task configuration page.

Configure the source and destination databases.

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	Database Type	Select SQL Server.
	Connection Type	Select Alibaba Cloud Instance.
	Instance Region	Select the region of the source ApsaraDB RDS for SQL Server instance.
	Replicate Data Across Alibaba Cloud Accounts	For this example, we are synchronizing data within the same Alibaba Cloud account. Select No.
	Instance ID	Select the ID of the source ApsaraDB RDS for SQL Server instance.
	Database Account	Enter the database account of the source ApsaraDB RDS for SQL Server instance. The account must have owner permissions on the objects to be synchronized.
	Database Password	Enter the password for the specified database account.
	Encryption	Select Non-encrypted or SSL-encrypted based on your requirements. If SSL encryption is not enabled for the source database, select Non-encrypted. If SSL encryption is enabled for the source database, select SSL-encrypted. DTS trusts the server certificate by default.
Destination Database	Database Type	Select MySQL.
	Connection Type	Select Alibaba Cloud Instance.
	Instance Region	Select the region of the destination ApsaraDB RDS for MySQL instance.
	Replicate Data Across Alibaba Cloud Accounts	For this example, we are synchronizing data within the same Alibaba Cloud account. Select No.
	RDS Instance ID	Select the ID of the destination ApsaraDB RDS for MySQL instance.
	Database Account	Enter the database account of the destination ApsaraDB RDS for MySQL instance. The account must have read and write permissions.
	Database Password	Enter the password for the specified database account.
	Connection Method	Select Non-encrypted or SSL-encrypted as needed. If you set this to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Use a cloud certificate to quickly enable SSL link encryption.

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.

Configure the task objects.

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

Parameter	Description
Synchronization Types	DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.
Schema Mapping Mode of Source and Destination Databases	Select a schema mapping mode as needed to map the schemas between the source and destination databases. Warning Tables in different schemas of the source database cannot have the same name. Otherwise, data inconsistency or task failure may occur.
SQL Server Incremental Synchronization Mode	Log-based Parsing for Non-heap Tables and CDC-based Incremental Synchronization for Heap Tables (Hybrid Log-based Parsing): Advantages: Supports scenarios with source database heap tables, tables without primary keys, compressed tables, and tables with computed columns. High link stability. This mode can obtain complete DDL statements and supports a wide range of DDL scenarios. Disadvantages: DTS creates the trigger `dts_cdc_sync_ddl`, the heartbeat table `dts_sync_progress`, and the DDL storage table `dts_cdc_ddl_history` in the source database. It also enables database-level Change Data Capture (CDC) and partial table CDC. You cannot execute `SELECT INTO`, `TRUNCATE`, and `RENAME COLUMN` statements on tables for which CDC is enabled in the source database. Triggers created by DTS in the source database cannot be manually deleted. Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported): Advantages: This mode is non-intrusive to the source database. Disadvantages: Does not support scenarios with source database heap tables, tables without primary keys, compressed tables, or tables with computed columns. Polling and querying CDC instances for incremental synchronization: Advantages: Supports full and incremental synchronization when the source database is Amazon RDS for SQL Server, Azure SQL Database, Azure SQL Managed Instance, Azure SQL Server on Virtual Machine, or Google Cloud SQL for SQL Server. Uses the native SQL Server CDC component to obtain incremental data, which makes incremental synchronization more stable and uses less network bandwidth. Disadvantages: The source database account used by the DTS instance must have the permission to enable CDC. Incremental data synchronization has a latency of about 10 seconds. In scenarios involving synchronization of multiple databases and tables, there may be risks of stability and performance issues.
The maximum number of tables for which CDC is enabled that DTS supports.	Set the maximum number of tables for which the current synchronization instance can enable CDC. The default value is 1000. Note This parameter is not available if you set SQL Server Incremental Synchronization Mode to Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported).
Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful. Note If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Database Table Column Name Mapping. Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example: If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database: During full data synchronization, DTS retains the destination record and skips the source record. During incremental synchronization, DTS overwrites the destination record with the source record. If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.
Capitalization of Object Names in Destination Instance	Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.
Source Objects	In the Source Objects box, click the objects, and then click to move them to the Selected Objects box. Note You can select objects at the database, table, or column level. If you select tables or columns as the synchronization objects, other objects such as views, triggers, and stored procedures are not synchronized to the destination database.
Selected Objects	To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name. To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk. Note To select the SQL operations to synchronize for a specific database or table, right-click the object in the Selected Objects box and select the desired SQL operations in the dialog box that appears. To filter data by using WHERE conditions, right-click the table to be synchronized in the Selected Objects box and specify the filter conditions in the dialog box that appears. For more information, see Use SQL conditions to filter data. If you rename an object, dependent objects may fail to synchronize.

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 if Synchronization Types is set to Full Data Synchronization. You can also adjust the rate of full data synchronization when the synchronization instance is running.
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).
Environment Tag	You can select an environment tag to identify the instance. In this example, no tag is selected.
Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
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. No: No alerts are configured. Yes: Configures alerts. You must also set the alert threshold and alert contact. For more information, see Configure monitoring and alerting during task configuration.

Click Data Verification to configure a data verification task.
To use the data verification feature, see Configure data verification.

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.

Purchase the instance.

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

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.

Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start, and then click OK in the OK dialog box.
You can monitor the task progress on the data synchronization page.