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Documentation > Virtual Machines > Overview of instance template

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Instance templates overview

Instance template is the configuration information template provided by JD Cloud for creating instances, including Image, Instance Type, System Disk and Data Disk Type and Capacity, Virtual Private Cloud, and Subnet Configuration, Security Group and Login Information, etc.

Instance templates can be used to create instances or for configuring Availability Groups. Once the instance template is successfully configured, you can quickly create the same configuration instance multiple times without having to re-specify the parameters already configured in the template, reducing deployment time.

Create an instance using the instance template: The default is to use the configuration in the instance template for initialization, and you need to specify configuration information not included in the instance template, such as availability zones, billing types, etc. You can also modify the configuration in the instance template if it does not meet your needs for this creation operation. Note that modifying the configuration only affects this creation operation and does not affect the instance template content. For details, see Create Instance.
Create a Availability Group using an instance template: An instance template must be specified when creating a Availability Group. After that, the configuration of new instances in the high availability group is the same as the configuration in the instance template, and the availability zone depends on the configuration of the high availability group, please refer to high availability groupfor details.

The instance template includes the following instance configuration information:

Information Items	Description
Geography	Physical location of the deployment of instances and other resources.
Image	Instance preconfigured environment containing the server's preconfigured environment (operating system and other installed software).
Instance specifications	Identifies the corresponding compute, memory, storage and network capabilities that determine the hardware configuration of the instance
Disk Information	System disk and data disk information.
Network	Virtual Private Cloud as a custom virtual network space for logical isolation between resources. You need to specify the Virtual Private Cloud and the corresponding subnet for the instance, and the intranet IP address will be assigned to the instance in the subnet CIDR range.
Elastic Public IP	Provides public access to instances, either with the creation of the instance or bound separately after creation.
Login Information	Instance login credentials, including password and key information, where the key is for Linux systems only.

Use Restrictions

A maximum of 20 instance templates are allowed to be created for a single geographic region; please submit a work order request if you have additional requirements;
The instance template does not support modification at the moment, if you need to modify some information items, we recommend you to create a new instance template;
Instance templates cannot be deleted if they are already referenced by a high availability group;
If the resources referenced by the instance template are deleted, the instance template will not be used normally, and the high availability group configured with the instance template will not be able to add instances normally, please also ensure that the resources associated with the instance template are available before use.