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|
|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.
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 typesFor 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.
For information about the pricing for each instance type, see ApsaraDB RDS for MySQL pricing.
You can change the type of your RDS instance between instance families as needed.
For detailed operations, resort to the following resources: