From MySQL to DDM¶
Supported Source and Destination Databases¶
Source DB | Destination DB |
|---|---|
|
|
Supported Migration Objects¶
Different types of migration tasks support different migration objects. For details, see Table 2. DRS will automatically check the objects you selected before the migration.
Type | Precautions |
|---|---|
Migration objects |
|
Database Account Permission Requirements¶
To start a migration task, the source and destination database users must have permissions listed in the following table. Different types of migration tasks require different permissions. For details, see Table 3. DRS automatically checks the database account permissions in the pre-check phase and provides handling suggestions.
Type | Full Migration | Full+Incremental Migration |
|---|---|---|
Source database user | The user must have the following minimum permissions: SELECT, SHOW VIEW, and EVENT | The user must have the following minimum permissions: SELECT, SHOW VIEW, EVENT, LOCK TABLES, REPLICATION SLAVE, and REPLICATION CLIENT |
Destination database user |
|
Suggestions¶
Caution
When a task is being started or in the full migration phase, do not perform DDL operations on the source database. Otherwise, the task may be abnormal.
To maintain data consistency before and after the migration, do not write data to the source and destination databases in the full migration mode. In the full+incremental migration mode, you can continue the migration while data is still being written to the source database.
The success of database migration depends on environment and manual operations. To ensure a smooth migration, perform a migration trial before you start the migration to help you detect and resolve problems in advance.
Start your migration task during off-peak hours. A less active database is easier to migrate successfully. If the data is fairly static, there is less likely to be any severe performance impacts during the migration.
If network bandwidth is not limited, the query rate of the source database increases by about 50 MB/s during full migration, and two to four CPUs are occupied.
The data being migrated may be locked by other transactions for a long period of time, resulting in read timeout.
Due to the inherent characteristics of MySQL, in certain scenarios the performance may be negatively affected. For example, if the CPU resources are insufficient and the storage engine is TokuDB, the read speed on tables may be decreased by 10%.
If DRS concurrently reads data from a database, it will use about 6 to 10 sessions. The impact of the connections on services must be considered.
If you read a table, especially a large table, during the full migration, the exclusive lock on that table may be blocked.
Data-Level Comparison
To obtain accurate comparison results, start data comparison at a specified time point during off-peak hours. If it is needed, select Start at a specified time for Comparison Time. Due to slight time difference and continuous operations on data, data inconsistency may occur, reducing the reliability and validity of the comparison results.
Precautions¶
The full+incremental migration process consists of four phases: task startup, full synchronization, incremental synchronization, and task completion. A single full migration task contains three phases. To ensure smooth migration, read the following precautions before creating a migration task.
Type | Restrictions |
|---|---|
Starting a task |
|
Full migration |
|
Incremental migration |
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Stopping a task |
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Prerequisites¶
You have logged in to the DRS console.
For details about the DB types and versions supported by real-time migration, see Real-Time Migration.
You have read Suggestions and Precautions.
Procedure¶
On the Create Replication Instance page, configure task details, description, and the replication instance, and click Next.
Task information description
Table 5 Task information¶ Parameter
Description
Region
The region where the replication instance is deployed. You can change the region. To reduce latency and improve access speed, select the region closest to your services.
Project
The project corresponds to the current region and can be changed.
Task Name
The task name must start with a letter and consist of 4 to 50 characters. It can contain only letters, digits, hyphens (-), and underscores (_).
Description
The description consists of a maximum of 256 characters and cannot contain special characters
!=<>'&"\Replication instance information
Table 6 Replication instance settings¶ Parameter
Description
Data Flow
Select To the cloud.
The destination is a DB instance on the current cloud.
Source DB Engine
Select MySQL.
Destination DB Engine
Select DDM.
Network Type
Available options: VPC, Public network, and VPN or Direct Connect. By default, the value is Public network.
VPC is suitable for migrations of cloud databases in the same region.
VPN and Direct Connect are suitable for migrations from on-premises databases to cloud databases or between cloud databases across regions.
Public network is suitable for migration from on-premises databases or external cloud databases to destination databases.
Destination DB Instance
The DDM instance you created.
Replication Instance Subnet
The subnet where the replication instance resides. You can also click View Subnet to go to the network console to view the subnet where the instance resides.
By default, the DRS instance and the destination DB instance are in the same subnet. You need to select the subnet where the DRS instance resides, and there are available IP addresses for the subnet. To ensure that the replication instance is successfully created, only subnets with DHCP enabled are displayed.
Migration Type
Full: This migration type is suitable for scenarios where service interruption is acceptable. All objects in non-system databases are migrated to the destination database at one time, including tables, views, stored procedures, and triggers.
Note
If you are performing a full migration, do not perform operations on the source database. Otherwise, data generated in the source database during the migration will not be synchronized to the destination database.
Full+Incremental: This migration type allows you to migrate data without interrupting services. After a full migration initializes the destination database, an incremental migration initiates and parses logs to ensure data consistency between the source and destination databases.
Note
If you select Full+Incremental, data generated during the full migration will be continuously synchronized to the destination database, and the source remains accessible.
Tags
Table 7 Tags¶ Parameter
Description
Tags
Tags a task. This configuration is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 20 tags.
After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.
On the Configure Source and Destination Databases page, wait until the replication instance is created. Then, specify source and destination database information and click Test Connection for both the source and destination databases to check whether they have been connected to the replication instance. After the connection tests are successful, select the check box before the agreement and click Next.
Source database configuration
Table 8 Source database settings¶ Parameter
Description
IP Address or Domain Name
The IP address or domain name of the source database.
Port
The port of the source database. Range: 1 - 65535
Database Username
The username for accessing the source database.
Database Password
The password for the database username.
SSL Connection
SSL encrypts the connections between the source and destination databases. If SSL is enabled, upload the SSL CA root certificate.
Note
The maximum size of a single certificate file that can be uploaded is 500 KB.
If SSL is disabled, your data may be at risk.
Note
The IP address, domain name, username, and password of the source database are encrypted and stored in DRS, and will be cleared after the task is deleted.
Destination database configuration
Table 9 Destination database settings¶ Parameter
Description
DB Instance Name
The DDM instance selected when you create the replication instance.
Database Username
The username for accessing the destination DDM database.
Database Password
The password for the database username.
Note
The username and password of the destination database are encrypted and stored in DRS, and will be cleared after the task is deleted.
On the Set Task page, select migration objects and click Next.
Table 10 Migration object¶ Parameter
Description
Migrate Object
You can migrate table-level objects to destination databases based on service requirements.
If the source database is changed, click
in the upper right corner before selecting migration objects to ensure that the objects to be selected are from the changed source database.Note
If an object name contains spaces, the spaces before and after the object name are not displayed. If there are two or more consecutive spaces in the middle of the object name, only one space is displayed.
The name of the selected migration object cannot contain spaces.
To quickly select the desired database objects, you can use the search function.
On the Check Task page, check the migration task.
If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
For details about how to handle check items that fail to pass the pre-check, see Solutions to Failed Check Items.
If the check is complete and the check success rate is 100%, click Next.
Note
You can proceed to the next step only when all checks are successful. If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.
On the Confirm Task page, specify Start Time and confirm that the configured information is correct and click Submit to submit the task.
Table 11 Task startup settings¶ Parameter
Description
Started Time
Set Start Time to Start upon task creation or Start at a specified time based on site requirements. The Start at a specified time option is recommended.
Note
The migration task may affect the performance of the source and destination databases. You are advised to start the task in off-peak hours and reserve two to three days for data verification.
After the task is submitted, view and manage it on the Online Migration Management page.
You can view the task status. For more information about task status, see Task Statuses.
You can click
in the upper right corner to view the latest task status.