This topic describes the instance families of ApsaraDB RDS. They are shared, general-purpose, dedicated, and dedicated cluster instance families. The shared and general-purpose instance families belong to the entry level, and the dedicated instance family belongs to the enterprise level.

Overview

Instance family Description Scenario
Shared instance family (entry-level) (supported only for SQL Server)
  • A shared instance exclusively occupies the allocated memory resources, but shares CPU and storage resources with the other shared instances that are deployed on the same physical host.
  • CPU resources are highly reused among shared instances that are deployed on the same physical host. This maximizes cost-effectiveness.
  • Shared instances may compete for resources.
  • Users pursue high cost-effectiveness to reduce costs.
  • Users require high availability but are not demanding for stability.
General-purpose instance family (entry-level)
  • A general-purpose instance exclusively occupies the allocated memory resources, but shares CPU and storage resources with the other general-purpose instances that are deployed on the same physical host.
  • CPU resources are moderately reused among general-purpose instances that are deployed on the same physical host. This increases cost-effectiveness.
  • The storage capacity of a general-purpose instance is independent of the number of CPU cores and memory capacity. You can flexibly configure the storage capacity based on your business requirements.
Users are not demanding for performance or stability.
Dedicated instance family (enterprise-level)
  • A dedicated instance exclusively occupies the allocated CPU and memory resources. Its performance remains stable and is not affected by the other instances that are deployed on the same physical host.
  • The top configuration of the dedicated instance family is dedicated host. A dedicated host instance occupies all the resources on the physical host where it is deployed.
Users use databases as core systems in sectors such as finance, e-commerce, government affairs, and large- and medium-sized Internet services.
Dedicated cluster instance family
  • You can log on to and perform operations and maintenance (O&M) operations on the hosts in a dedicated cluster.
  • A dedicated cluster instance exclusively occupies all the resources on the virtual or physical host where it is deployed.
  • You can create more than one RDS instance on a host based on your business requirements.
Dedicated cluster instances benefit from the flexible resource scheduling that is delivered by ApsaraDB RDS and can meet your requirements for regulatory compliance, high performance, and security. For more information, see What is ApsaraDB for MyBase?
  • Users have manageable hosts and want to migrate their O&M systems to the cloud.
  • Users want to allocate resources based on a proper overcommit ratio to reduce the overall expenditure.

Cost-effectiveness advantages of the dedicated instance family

The dedicated instance family (enterprise-level) and the general-purpose instance family (entry-level) each have some unique performance metrics that cannot be directly compared. The following table is a cost-effectiveness comparison between the two instance families based on similar specifications. The comparison provides a basis for you to make purchase decisions.

Instance family CPU cores and memory capacity Storage capacity Maximum number of connections Maximum IOPS Monthly subscription fee
General-purpose instance family (entry-level) 4 CPU cores, 16 GB 500 GB 4000 7000 USD 320
Dedicated instance family (enterprise-level) 4 CPU cores, 32 GB 500 GB 5000 9000 USD 550

Based on the preceding table, 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 general-purpose instance. In addition, a dedicated instance provides stable CPU and storage performance. If the dedicated instance family is used in suitable business scenarios, it can deliver high cost-effectiveness.

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 prices of various instance types, visit the ApsaraDB RDS buy page

Change of the instance family

You can change the instance type of your RDS instance between the dedicated and general-purpose instance families based on your business requirements.

Note
  • You cannot change the instance type of your RDS instance from the shared instance family to another instance family. If necessary, you can create an RDS instance that belongs to another instance family and then 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.
  • You cannot change the instance type of your RDS instance from the dedicated cluster instance family to another instance family. If necessary, you can create an RDS instance that belongs to another instance family and then use DTS to migrate the data of your RDS instance to the new RDS instance. For more information, see Migrate data from a user-created database to ApsaraDB for MyBase.

For more information about how to change the instance family of your RDS instance, see the following topics:

FAQ

A general-purpose instance and a dedicated instance have the same CPU cores and memory capacity. Why does the general-purpose instance support a larger maximum number of connections and deliver higher IOPS than the dedicated instance?

A dedicated instance exclusively occupies the allocated CPU and memory resources, whereas a general-purpose instance exclusively occupies only the allocated memory resources. Therefore, a general-purpose instance delivers higher performance than a dedicated instance due to flexible resource scheduling. However, a dedicated instance runs more stably than a general-purpose instance. For more information, see the "Overview" section of the topic.