ApsaraDB RDS for SQL Server supports the inter-instance database replication feature. You can replicate databases on an ApsaraDB RDS for SQL Server instance to another ApsaraDB RDS for SQL Server instance.
Prerequisites
- The source and destination RDS instances belong to the same Alibaba Cloud account.
- The major engine versions of the source and destination RDS instances are the same.
The following list describes the supported major engine versions:
- SQL Server 2012
- SQL Server 2016
- SQL Server 2008 R2 with standard SSDs or enhanced SSDs (ESSDs)
- The region and network type of the source RDS instance must be the same as those of the destination RDS instance. The zones of the source and destination RDS instances can be different.
- The destination RDS instance does not have databases whose names are the same as those of the databases that you want to replicate from the source RDS instance.
- The available storage of the destination RDS instance is larger than the total size of the databases that you want to replicate from the source RDS instance.
Description
During the replication process, ApsaraDB RDS first performs a full backup on the source RDS instance and then replicates the full data to the destination RDS instance. If data is written to the source RDS instance during the replication, incremental data of the source RDS instance is not replicated to the destination RDS instance.
You can choose to replicate a single database or all databases in the source RDS instance. If the replication task fails, no data is replicated to the destination RDS instance. This ensures data consistency.
Comparison between the database replication feature of ApsaraDB RDS and the data migration feature of DTS
Item | Database replication | Data migration |
---|---|---|
Principle | ApsaraDB RDS replicates databases from the source RDS instance to the destination RDS instance by using data backup files or to a point in time. The feature does not delete data from the source RDS instance. | The data migration feature that is provided by Data Transmission Service (DTS) performs logical migration. You can use the data migration feature to read and parse the logs of the source instance to migrate the data. A complete data migration process consists of three phases: schema migration, full data migration, and incremental data migration. The feature does not delete data from the source instance. |
Data source | ApsaraDB RDS for SQL Server instances. | Self-managed databases that are deployed on Elastic Compute Service (ECS) instances, self-managed databases that are deployed in data centers, self-managed databases that are deployed on third-party cloud servers, and ApsaraDB RDS for SQL Server instances. For more information, see Supported databases. |
Implementation | Only one-time full replication is supported. The one-time full replication is free of charge. | Schema migration, full data migration, and incremental data migration are supported. For more information about the charges for incremental data migration, see Billing overview. |