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

Instance families

Family Description Scenario
Shared instance family

(Not supported)

  • A shared instance exclusively occupies the memory resources allocated to it, but shares CPU and storage resources with the other shared instances that are deployed on the same server.
  • CPU resources are highly reused among shared instances that are deployed on the same server to maximize CPU cost-effectiveness.
  • Shared instances may compete for resources.
  • Users pursue cost-effectiveness.
  • Users prefer high availability to stability.
General-purpose instance family
  • A general-purpose instance exclusively occupies the memory resources allocated to it, but shares CPU and storage resources with the other general-purpose instances that are deployed on the same server.
  • CPU resources are moderately reused among general-purpose instances that are deployed on the same server to increase CPU cost-effectiveness.
  • The storage capacity of a general-purpose instance is independent of CPU cores and memory capacity. You can flexibly configure the storage capacity based on your business requirements.
Users are less concerned with performance and stability.
Dedicated instance family A dedicated instance exclusively occupies the CPU and memory resources allocated to it. Its performance remains stable for a long term and is not affected by the other instances that are deployed on the same server.

The top configuration of this instance family is dedicated host. A dedicated host instance occupies all of the resources on the server where it resides.

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

The following figure shows the differences between the three instance families.

Cost-effectiveness comparison

The three instance families each have some unique performance metrics and therefore cannot be directly compared. The following table is a comparison of cost-effectiveness between the three instance families by using instance types with similar specifications as examples. This comparison provides a basis for you to make purchase decisions.

Family CPU cores and memory capacity Storage capacity Maximum number of connections Maximum IOPS Monthly subscription fee
Shared or general-purpose instance family 4 CPU cores, 16 GB 500 GB 4,000 7,000 USD 320
Dedicated instance family 4 CPU cores, 32 GB 500 GB 5,000 9,000 USD 550

Based on the preceding comparison, a dedicated instance costs 70% more but provides twice as much memory capacity, 25% more connections, and 28% higher input/output operations per second (IOPS) than a shared or general-purpose instance. The dedicated instance family delivers high cost-effectiveness if it is used in suitable business scenarios.

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 Primary instance types.

Pricing

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

Change the instance family

You can change the family and specifications of your RDS instance based on your business requirements.

Note You cannot directly upgrade your RDS instance from the shared instance family to the general-purpose or dedicated family. You must create an RDS instance that belongs to the general-purpose or dedicated instance family. Then, you can use Alibaba Cloud Data Transmission Service (DTS) to migrate the data of your RDS instance to the new RDS instance. For more information, see Data migration solutions.

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 shared or general-purpose 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 when the same CPU and memory specifications are used. However, an enterprise-level instance is more stable because it exclusively occupies the CPU and memory resources allocated to it. For more information, see Overview.