Introduction

Last Updated: Aug 10, 2017

Welcome to Alibaba Cloud Elastic Compute Service (ECS). You can use the APIs described in this document to perform relevant operation on ECS.

Note: Before using these APIs, make sure that you have fully understood the ECS product instructions, user agreements, and billing methods.

Glossary

Term Full name Description
Instance ECS Instance It is a computer virtualized by a physical server by using the virtualization technology.
Region Region It represents the region where resources are located. Each region contains a group of zones.
Zone Zone Zones are physical areas in the same region with independent power grids and networks. The network latency for ECS instances within the same zone is shorter. Intranet communication can take place between zones in the same region, and fault isolation can be performed between zones.
Image Image File Operating systems and application software can be made into image files. You can select one image file to initialize ECS instances.
Images are necessary for the creation of instances. All system disk contents of a newly created instance are copied from images, including the operating system and software configuration. The image files to be selected depend on the operating system your instance is using.
Disk Disk It is a storage device of instances.
Snapshot Snapshot A snapshot is a restore point created for a disk. It contains the disk data at the specified time and can be used to restore disk data or create custom images.
IP Internet Protocol It indicates the public IP address on the Internet.
Security Group Security Group It indicates an instance-related security group. Security policies can be assigned for security groups. An instance may belong to one or more security groups. The security policies of a security group apply to all instances in the group.
CIDR Classless Inter-Domain Routing CIDR is a new addressing mode used on the Internet. Compared with the conventional class A, class B, and class C addressing schemes, CIDR implements more efficient IP address allocation.
For example, to convert the IP segment 125.203.96.0 - 125.203.127.255 into CIDR format, find the same first 19 bits:
125.203.0110 0000.0000 0000 to 125.203.0111 1111.1111 1111 can be represented by 125.203.96.0/19.

Description of business restrictions and type constraints

In ECS, the quantity of instances, security groups, and other resources for each user is limited.

The specifications such as the instance type, number of disks attached to each instance, disk capacity, number of disk snapshots, and public bandwidth of the instance are also limited. When using ECS OpenAPI, refer to the latest restrictions on business rules and resource types on the official website. Query links.

In the API description section, whenever there is a conflict with the resource or specification constraints given on the official website concerning optional parameter values or available specifications, the information on the official website prevails.

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