This topic provides an overview of RDS instance type families, including general-purpose instances and dedicated instances.

Instance type families

Instance type family Description Applicable scenario
General-purpose instances
  • A general-purpose instance owns the memory resources allocated to it and shares CPU and storage resources with the other general-purpose instances that are deployed on the same physical host.
  • A cost-effective instance type that maximizes utilization by reusing resources for scaling scenarios.
  • Its storage capacity is not subject to CPU or memory restrictions, allowing flexible configurations.
  • Scenarios where cost-effectiveness is a priority.
  • Scenarios where high-performance stability is not required.
Dedicated instances A dedicated instance owns the CPU and memory resources allocated to it. It runs stably for a long term, and its performance does not deteriorate due to operations from the other instances that are deployed on the same physical host.

As an upgraded version of dedicated instance, a dedicated-host instance owns all the resources on the physical host where it is deployed.

Scenarios that typically involve medium- to large-scale business that uses a database-centric system.

The differences between general-purpose and dedicated instances are shown in the following figure.

Differences between common and dedicated instances

Comparison in cost-effectiveness

The types and performance metrics of dedicated instances do not completely match those of general-purpose instances. To help you compare the types and performance of the two instance type families and better make purchase decisions, we use two types that are similar in the two families as examples to analyze their cost-effectiveness.

Instance type family Type CPU/memory Disk space Maximum number of connections Maximum IOPS Price for subscription billing
General-purpose instances rds.mysql.m1.medium 4 cores, 16 GB 500 GB 4,000 7,000 USD 2,726
Dedicated instances mysql.x8.large.2 4 cores, 32 GB 500 GB 5,000 9,000 USD 5,481

Based on the preceding table, although a dedicated instance is 50% more expensive than a general-purpose instance that is in a similar type, the dedicated instance provides two times as many memory resources as the general-purpose instance. As such, the maximum number of connections and maximum IOPS of the dedicated instance increase by 25% and 28%, respectively, compared with the general-purpose instance, and yet the dedicated instance still provides stable CPU and storage performance.

Instance types

For information about RDS instance types and the number of CPU cores, memory size, storage capacity, maximum number of connections, and maximum IOPS in each type, see Instance types.

Pricing

For information about the pricing for each instance type, see ApsaraDB RDS for MySQL pricing.

Type changes

You can change the type of your RDS instance between instance families as needed.

For detailed operations, resort to the following resources: