Terms

This topic describes the terms used in RDS.

No.	Term	Description
1	Instance	RDS instance, or simply instance, is the basic unit for creating RDS services. The instance is the running environment of Database RDS version, and exists as a separate process on the host. You can create, modify, and delete RDS instances through the console. Each instance is independent and resource isolated from each other, and there are no preemptive issues such as CPU, memory, IO, etc. Each instance has its own characteristics, such as database type, version, etc., and the system has corresponding parameters to control instance behavior.
2	Memory	The maximum memory limit that cloud database RDS instances can use.
3	Disk Capacity	The disk capacity is the size of the disk you choose to create when creating an RDS instance. The disk capacity occupied by the instance not only includes the collection data, but also the space required for the normal operation of the instance, such as system databases, database rollback logs, redo logs, indexes, etc. Please ensure that the RDS instance has sufficient disk capacity to store data, otherwise it may cause the instance to be locked. If the instance is locked due to insufficient disk capacity, you can create a larger disk capacity to unlock the instance.
4	IOPS	The maximum number of block device read and write operations per second, in 4KB units.
5	CPU Core	The upper limit of computing power that an instance can use. One CPU has computing power of no less than 2.3GHz Hyper-Threading (Intel Xeon series Hyper-Threading).
6	Number of connections	TCP connection between client and RDS instance. If the client uses connection pooling, the connection between the client and the RDS instance is a long connection, otherwise it is a short connection.