Overview of a CVM Instance

An instance is a Cloud Virtual Machine (CVM). It contains basic computing components such as the CPU, the memory, the operating system, the network, and the disk.

CVM instances provide elastic computing services in the cloud in a secure and reliable way to meet computing requirements. As business demands change, computing resources can be scaled in real time to lower your software and hardware costs and simplify IT OPS work.

Each instance type offers different computing and storage capabilities, making them suitable for different use cases. You can choose the computing capacity, storage, and network access method of the instance based on the scope of the service you need to provide. For more information about instance types and use cases, see Instance Types. After you launch an instance, you can use it as you would any traditional computer. You will also have complete control over your instances.

Instance Image

An Image is a template that contains software configurations (operating systems, pre-installed programs, etc.) required for launching CVM instances. You can use an image to launch an instance or multiple instances repeatedly. In other words, an image is the “installed disk” of the CVM.

Tencent Cloud provides the following types of images:

• Public image: available to all users and suitable for major operating systems.
• Custom image: only available to the creator and the users with whom the image is shared. A custom image is created from running instances or imported from external sources.
• Shared image: shared by other users. They can only be used to create instances.

For more information about images, see Overview or Image Types Overview.

Instance Storage

Similar to a normal CVM, instances can be stored in the system disk and the data disk:
System disk: similar to the C drive in the Windows system. The system disk contains a full copy of the image used to launch an instance and the running environment for the instance. A system disk larger than the used image is required when an instance is launched.
Data disk: similar to the D and E drives in the Windows system. The data disk saves user data and supports flexible expansion, mounting, and unmounting.

Both the system disk and the data disk support different types of storage provided by Tencent Cloud. For more information, please see Storage Overview.

Instance Security

Tencent Cloud provides the following instance security protection methods:

• Policy: when different accounts need to control the same set of cloud resources, you can use a policy to control their access to cloud resources.
• Security groups: you can use a security group to control the access of trusted addresses to instances.
• Login control: log in to your Linux instances using SSH keys as much as possible. If you log in to your Linux instances using login passwords, change your passwords periodically.