This topic describes the instance families of ApsaraDB RDS. They are shared, general-purpose, and dedicated instance families. Different instance families support different specifications and are suitable for different scenarios.
|Shared instance family
|General-purpose instance family||
||Business that is not demanding on performance and stability.|
|Dedicated instance family||A dedicated instance exclusively occupies the CPU and memory resources allocated to
it. Its performance remains stable and is not affected by 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 resources on the server where it is deployed.
|Business that uses databases as the core system, such as finance, e-commerce, government affairs, and large- and medium-sized Internet services.|
The following figure shows the differences between the three instance families.
The three instance families have some unique performance metrics that cannot be directly compared. The following table is a comparison of costs between the three instance families based on instance types with similar specifications. This comparison provides a basis for you to make purchase decisions.
|Instance family||CPU cores and memory capacity||Storage capacity||Maximum connections||Maximum IOPS||Monthly subscription fee|
|Shared or general-purpose instance family||4 CPU cores, 16 GB||500GB||4000||7000||USD 320|
|Dedicated instance family||4 CPU cores, 32 GB||500GB||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 shared or general-purpose instance. A dedicated instance also provides more stable CPU and storage performance. The dedicated instance family delivers high cost effectiveness if it is used in suitable business scenarios.
Instance typesFor 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.
For more information about the price of each instance type, see the ApsaraDB RDS pricing page.
Change of the instance family
You can change the instance family and specifications of your RDS instance based on business requirements.
For more information about how to change the specifications of your RDS instance, see the following topics:
- Change the specifications of an ApsaraDB RDS for MySQL instance
- Change the specifications of an ApsaraDB RDS for SQL Server instance
- Change the specifications of an ApsaraDB RDS for PostgreSQL instance
- Change the specifications of an ApsaraDB RDS for PPAS instance
- Change the specifications of an ApsaraDB RDS for MariaDB instance
Why does an entry-level RDS instance outperform an enterprise-level instance? The entry-level RDS instance belongs to the shared or general-purpose instance family, whereas the enterprise-level RDS instance belongs to the dedicated instance family.
Therefore, the entry-level RDS instance supports a larger maximum number of connections and delivers higher IOPS than the enterprise-level RDS instance even when they have the same CPU and memory specifications. However, the enterprise-level RDS instance is more stable because it exclusively occupies CPU and memory resources. For more information, see Instance families.