This topic describes the three instance families of ApsaraDB for RDS. They are general-purpose, general-purpose 2, and dedicated instance families.

Overview

Instance family Description Application scenario
General-purpose 2 instance

Not supported

  • A general-purpose 2 instance occupies exclusive memory resources allocated to it, but shares CPU and storage resources with the other general-purpose 2 instances on the same physical host.
  • CPU resources are frequently reused among general-purpose 2 instances on the same physical host to maximize CPU cost effectiveness.
  • General-purpose 2 instances may compete for resources.
Note The general-purpose 2 instance family is only supported for the High-availability Edition used with SQL Server.
  • Users pursue cost-effectiveness.
  • Users prefer high availability to stability.
General-purpose instance
  • A general-purpose instance occupies exclusive memory resources allocated to it, but shares CPU and storage resources with the other general-purpose instances on the same physical host.
  • CPU resources are commonly reused among general-purpose instances on the same physical host to increase CPU cost effectiveness.
  • The storage capacity of a general-purpose instance is independent of CPU cores and memory capacity. Storage capacity can be flexibly configured to fit into your business needs.
Users are less concerned with performance and stability.
Dedicated instance A dedicated instance occupies exclusive CPU and memory resources allocated to it. Its performance and stability are independent of the other instances on the same physical host.

The top configuration of this instance family is dedicated host. A dedicated-host instance occupies all resources on the physical host housing it.

Users are engaged in database-centered businesses such as finance, e-commerce, governmental affairs, and other large- and medium-sized Internet services.

The following figure shows differences between the general-purpose, general-purpose 2, and dedicated instance families.

Cost-effectiveness comparison

The three instance families each have their own different performance metrics and therefore cannot be directly compared. The following table is a comparison in cost-effectiveness between them by using instance types with similar specifications as an example. This comparison provides a basis for you to make your purchase decisions.

Instance family CPU and memory Storage capacity Maximum connections Maximum IOPS Monthly subscription price
General-purpose instance or general-purpose 2 instance 4 cores, 16 GB 500 GB 4,000 7,000 USD 2,100
Dedicated instance 4 cores, 32 GB 500 GB 5,000 9,000 USD 3,650

Based on the above comparison, a dedicated instance costs 70% more but provides twice as much memory capacity, 25% more connections, and 28% higher IOPS than a general-purpose instance or general-purpose 2 instance. This means that the dedicated instance family delivers the highest cost-effectiveness among the three instance families.

Instance types

For more information about instance types and their specifications such as the number of CPU cores, memory capacity, storage capacity, maximum number of connections, and IOPS, see Instance types.

Pricing

For more information about the price of each instance type, visit ApsaraDB RDS for MySQL.

Change instance types

You can change the instance family and specifications of your ApsaraDB for RDS instance as needed.

For more information, see the following topics:

FAQ

Why does an entry-level instance outperform an enterprise-level instance?

An entry-level instance belongs to the general-purpose or general-purpose 2 instance family, whereas an enterprise-level instance belongs to the dedicated instance family. Therefore, an entry-level instance supports a larger maximum number of connections and delivers higher IOPS than an enterprise-level instance with the same CPU and memory specifications. However, an enterprise-level instance is more stable due to its exclusive CPU and memory resources. For more information, see Overview.