RDS Basic Edition is a single-node database edition with decoupled compute and storage. It has no secondary instance, which means no replication overhead and 50% lower cost than RDS High-availability Edition — but also no automatic failover.
Because RDS Basic Edition has no standby instance, unexpected failures, instance specification changes, and database engine upgrades can all cause extended downtime (up to 30+ minutes). For production workloads that require high availability, use RDS High-availability Edition instead. You can upgrade at any time — see Upgrade the edition.
Choose an edition
Use this table to decide whether RDS Basic Edition fits your requirements.
| RDS Basic Edition | RDS High-availability Edition | |
|---|---|---|
| Architecture | Standalone (single node) | Primary + secondary instance |
| Automatic failover | No | Yes |
| Primary/secondary switchover | Not supported | Supported |
| Read-only instances | Not supported | Supported |
| Log management | Not supported | Supported |
| IP address whitelist | Supported | Supported |
| Monitoring and alerting | Supported | Supported |
| Backup and restore | Supported | Supported |
| Downtime during engine upgrade or spec change | Up to 30+ minutes | Minimal |
| Price | 50% less than High-availability Edition | Baseline |
For the full feature list, see Features of ApsaraDB RDS for SQL Server.
How it works
RDS Basic Edition separates compute and storage into independent layers:
Compute layer: The database engine runs on a single compute node. No data is replicated to a secondary instance, so there is no replication overhead — which is why RDS Basic Edition delivers higher throughput than RDS High-availability Edition at the same configuration.
Storage layer: Database files reside on cloud disks managed by Alibaba Cloud's Apsara distributed system, which keeps multiple copies of your data. Compute resources are decoupled from storage resources, which prevents data loss when compute nodes fail.
The reliability of your database service is ensured by the ultra-large Apsara distributed operating system of Alibaba Cloud that keeps multiple copies of your data.
Use cases
RDS Basic Edition is suited for non-production environments and cost-sensitive workloads:
Development and testing: Provision instances quickly and scale them with your workload. Fast provisioning keeps Research and Development (R&D) cycles short.
Learning and evaluation: If you are getting started with ApsaraDB RDS, RDS Basic Edition lets you explore the service at lower cost.
Small websites and applications: Offload routine O&M tasks to Alibaba Cloud and focus on your application. RDS Basic Edition works well when traffic is predictable and brief downtime is acceptable.
Features
Basic Edition supports basic features such as IP address whitelists, Monitoring and Alerts, and backup and recovery. It does not support the following features:
For a list of supported features, see SQL Server feature overview.
Limitations
RDS Basic Edition runs on a single node. Features that depend on a primary-secondary architecture are not available:
No automatic failover: If the compute node fails, the system migrates the database engine to a new node. Your instance is unavailable during migration — in extreme cases, for more than 30 minutes.
No primary/secondary switchover: Without a secondary instance, there is no standby to switch to.
No read-only instances: Read replicas require a primary-secondary setup and are not supported.
No log management: Log management features available in other editions are not supported.
Extended downtime during maintenance: When you change instance specifications or upgrade the database engine, the system checks whether the current physical server has enough resources. If not, it migrates your data to a new server — potentially interrupting connectivity for more than 30 minutes.
Setting the log backup frequency to Every 30 Minutes lets you restore data to a point in time within the last 30 minutes if a cloud disk failure or similar issue occurs. For details, see Back up an ApsaraDB RDS for SQL Server instance.
Create an instance
To create an RDS Basic Edition instance and connect to a SQL Server database, see Create an ApsaraDB RDS for SQL Server instance.
Upgrade the edition
You can upgrade an RDS Basic Edition instance to RDS High-availability Edition at any time. See Upgrade an ApsaraDB RDS for SQL Server instance from Basic Edition to High-availability Edition.
Downgrading from RDS High-availability Edition to RDS Basic Edition is not supported. To achieve the equivalent result, create a new RDS Basic Edition instance, migrate your data from the existing High-availability Edition instance, and then release the original instance. See Migrate data between ApsaraDB RDS for SQL Server instances and Release or unsubscribe from an RDS instance.
FAQ
Why do engine upgrades and instance specification changes take so long on RDS Basic Edition?
RDS Basic Edition uses a standalone architecture with a single compute node. When you upgrade the database engine or change instance specifications, the system checks whether the current physical server can meet the new resource requirements. If not, it migrates all data to a new physical server before switching over — potentially interrupting connectivity for more than 30 minutes.
We recommend that you select RDS Enterprise Edition or RDS Cluster Edition. These editions are based on the high-availability architecture, which allows you to replicate data from the secondary RDS instance without impacts on your workloads, keeping downtime minimal. See RDS High-availability Edition and RDS Cluster Edition for details.
Why does RDS Basic Edition support fewer features than other editions?
Features like primary/secondary switchover, read-only instances, and log management all require a secondary instance to function. Because RDS Basic Edition is a single-node architecture, those features are not architecturally possible. For a complete feature comparison, see Features of ApsaraDB RDS for SQL Server.