Real-Time Migration

In real-time migration, you only need to configure the source database, destination database, and migration objects. DRS will help you compare and analyze data so you can determine when to migrate with minimal service disruption.

Supported Database Types

DRS supports migration between different DB engines. The following table lists the supported data sources. Self-built databases include on-premises databases and ECS databases.

**Table 1** Database types
Migration Direction	Data Flow	Source DB	Destination DB	Destination DB Type
To the cloud	MySQL->MySQL	On-premises databases ECS databases Databases on other clouds RDS for MySQL DB instances	RDS for MySQL DB instances	Single DB instance Primary/Standby DB instance
From the cloud	MySQL->MySQL	RDS for MySQL DB instances	On-premises databases ECS databases Databases on other clouds	Single DB instance Primary/Standby DB instance

**Table 2** Database versions
Migration Direction	Data Flow	Source DB Version	Destination DB Version
To the cloud	MySQL->MySQL	MySQL 5.5.x MySQL 5.6.x MySQL 5.7.x MySQL 8.0.x	MySQL 5.6.x MySQL 5.7.x MySQL 8.0.x
From the cloud	MySQL->MySQL	MySQL 5.6.x MySQL 5.7.x MySQL 8.0.x	MySQL 5.6.x MySQL 5.7.x MySQL 8.0.x

Supported Migration Types

DRS supports two migration types: full migration and full+incremental migration.

This full migration type is suitable for scenarios where service interruption is acceptable. All objects and data in non-system databases are migrated to the destination database at one time. The objects that can be migrated include tables, views, stored procedures, and triggers.

The full+incremental migration type allows you to migrate data without interrupting services. After a full migration initializes the destination database, an incremental migration parses logs to ensure data consistency between the source and destination databases.

**Table 3** Migration types
Migration Direction	Data Flow	Full Migration	Full+Incremental Migration
To the cloud	MySQL->MySQL	Supported	Supported
From the cloud	MySQL->MySQL	Supported	Supported

Supported Network Types

DRS supports data migration through a Virtual Private Cloud (VPC), Virtual Private Network (VPN), Direct Connect, or public network. Table 4 lists the application scenarios of each network type and required preparations, and Table 5 lists the supported network types of each migration scenario.

**Table 4** Network types
Network Type	Application Scenario	Preparations
VPC	Migrations between cloud databases in the same region	The source and destination databases must be in the same region. The source and destination databases can be in either the same VPC or in different VPCs. If source and destination databases are in the same VPC, they can communicate with each other by default. Therefore, you do not need to configure a security group. If the source and destination databases are not in the same VPC, the CIDR blocks of the source and destination databases cannot be duplicated or overlapped, and the source and destination databases are connected through a VPC peering connection. DRS automatically establishes a route through a single IP address when you test the network connectivity.
VPN	Migrations from on-premises databases to cloud databases or between cloud databases across regions	Establish a VPN connection between your local data center and the VPC that hosts the destination database. Before migration, ensure that the VPN network is accessible.
Direct Connect	Migrations from on-premises databases to cloud databases or between cloud databases across regions	Use a dedicated network connection to connect your data center to VPCs.
Public network	Migrations from on-premises or other cloud databases to destination databases	To ensure network connectivity between the source and destination databases, perform the following operations: Enable public accessibility. Enable public accessibility for the source database based on your service requirements. Configure security group rules. Add the EIPs of the replication instance to the whitelist of the source database for inbound traffic. If destination databases and the replication instance are in the same VPC, they can communicate with each other by default. You do not need to configure a security group. NOTE: The IP address on the Configure Source and Destination Databases page is the EIP of the replication instance. If SSL is not enabled, migrating confidential data is not recommended.

**Table 5** Supported network types
Migration Direction	Data Flow	VPC	Public Network	VPN or Direct Connect
To the cloud	MySQL->MySQL	Supported	Supported	Supported
From the cloud	MySQL->MySQL	Supported	Supported	Supported

Migration Objects

DRS allows you to migrate objects at different levels. The following table lists the supported migration objects.

**Table 6** Supported migration objects
Migration Direction	Data Flow	Full Migration	Table-Level Migration	Database-Level Migration
To the cloud	MySQL->MySQL	Supported	Supported	Supported
From the cloud	MySQL->MySQL	Supported	Supported	Supported

Advanced Features

DRS supports multiple features to ensure successful real-time migration.

**Table 7** Advanced features
Feature	Description
Flow control	Allows you to limit the overall migration speed to make the impact of migration on bandwidth and database I/O controllable. Flow control mode takes effect only during a full migration.
Account migration	Allows you to migrate accounts, permissions, and passwords.
Parameter comparison	Checks the consistency of common parameters and performance parameters between source and destination databases to ensure that the migrated service is running properly.