This topic provides an overview of ApsaraDB RDS for SQL Server and describes the related concepts.

ApsaraDB RDS is a stable, reliable, and scalable online database service that is built on top of the Apsara Distributed File System and high-performance SSDs of Alibaba Cloud. ApsaraDB RDS supports the MySQL, SQL Server, PostgreSQL, and MariaDB database engines. ApsaraDB RDS provides a complete suite of solutions for various scenarios, such as disaster recovery, backup, restoration, monitoring, and migration, to facilitate database O&M. For more information about the benefits of ApsaraDB RDS, see Competitive advantages of ApsaraDB RDS instances over self-managed databases.

If your workloads are complex, you can purchase a support plan to obtain exclusive support provided by instant messaging (IM) enterprise groups, technical account managers (TAMs), and service managers.

For more information about ApsaraDB RDS, visit the ApsaraDB RDS for MySQL product page .


Some features or functions that are described in this document may be unavailable. The specific terms and conditions in your commercial contract shall prevail. This document serves as a user guide that is for reference only. Content in this document is provided without warranty of any kind, expressed or implied.

ApsaraDB RDS for SQL Server

ApsaraDB RDS for SQL Server is built on top of a high-availability architecture and supports the restoration of data to a specific point in time. These highlights enable ApsaraDB RDS for SQL Server to support various enterprise applications. In addition, ApsaraDB RDS for SQL Server includes Microsoft-issued licenses, which eliminates the need to purchase licenses and reduces costs.
Note The license for an ApsaraDB RDS for SQL Server instance is approved based on the number of cores that are configured for the instance. You do not need to obtain a client access license.
ApsaraDB RDS for SQL Server provides the following advanced features:
  • ApsaraDB for MyBase dedicated clusters: An ApsaraDB for MyBase dedicated cluster consists of multiple hosts, such as Elastic Compute Service (ECS) instances of the ecs.i2.xlarge instance type and ECS Bare Metal instances. You can deploy RDS instances on these hosts based on your varying business requirements. For more information, see What is ApsaraDB for MyBase?
  • Disk encryption: This feature encrypts the entire data disks of your RDS instance based on block storage. Your data cannot be accessed even if data leaks occur. For more information, see Configure disk encryption for an ApsaraDB RDS for SQL Server instance. This feature does not interrupt your workloads. You can use this feature without the need to modify your application.
  • Read-only RDS instances: If the number of read requests that your database system needs to process is significantly greater than the number of write requests, a single primary RDS instance may not be able to efficiently process read requests and your workloads may be interrupted. To offload read requests from the primary RDS instance, you can create one or more read-only RDS instances. For more information, see Create a read-only ApsaraDB RDS for SQL Server instance. This way, you can increase the read capability of your database system and increase the throughput of your application.
  • Read/write splitting: After read-only RDS instances are created, you can enable the read-only routing endpoint and add the endpoint of the primary RDS instance and the read-only routing endpoint to your application. Your database system forwards write requests to the primary RDS instance and read requests to the read-only routing endpoint. Then, the read-only routing endpoint forwards the read requests to the read-only RDS instances based on the read weights of the read-only RDS instances. For more information, see Overview of read/write splitting.

For more information about the features that are supported by ApsaraDB RDS for SQL Server, see SQL Server 2019.

Basic terms

  • Instance: An RDS instance is a database process that consumes independent physical memory resources. You can specify a specific memory size, storage capacity, and database type for an RDS instance. The performance of an RDS instance varies based on the specified memory size. After an RDS instance is created, you can change its specifications or delete the instance.
  • Database: A database is a logical unit that is created on an RDS instance. One RDS instance can have multiple databases. Each database must have a unique name on the RDS instance on which the database created.
  • Region and zone: Each region is a physical data center. Each region has multiple isolated locations known as zones. Each zone has its own independent power supply and network. For more information, see Global infrastructure of Alibaba Cloud.

General terms

On-premises databaseA database that is deployed in a data center or a database that is not deployed on an ApsaraDB RDS instance.
ApsaraDB RDS for XX (XX represents one of the following database engines: MySQL, SQL Server, PostgreSQL, and MariaDB.)ApsaraDB RDS with a specific database engine. For example, ApsaraDB RDS for MySQL indicates an ApsaraDB RDS instance that runs MySQL.