Overview

Scenarios

If the ECS specifications cannot meet service requirements, you can modify the specifications by upgrading the vCPUs and memory.

For certain ECSs, you can change their virtualization types when modifying their specifications.

Notes

Before modifying specifications, ensure that the NetworkManager service is enabled. Otherwise, the IP address will be lost and the network will be disconnected.
Run the following command to check whether the NetworkManager service is enabled:

systemctl is-enabled NetworkManager

Execution result:
- enabled: NetworkManager is enabled.
- disabled: NetworkManager is disabled. Run the systemctl enable NetworkManager command to enable it.
Before modifying specifications, ensure that the /etc/fstab file is configured correctly. Otherwise, the system may fail to restart. For details, see What Should I Do If My Linux ECS Fails to Start Due to Incorrect /etc/fstab File Configuration?
Modifying specifications may change the disk device number due to the disk driver change. If there are any service dependencies, handle the issue in a timely manner, or change the specifications to those that do not involve disk driver changes.
Generally, this issue occurs on the following specifications that only support the SCSI disk type.
- General computing-plus: C7 and C6h
- Memory-optimized: M7

Constraints

The following table lists the constraints on ECS specification modification.

**Table 1** Constraints
Item		Description
Billing mode		Spot pricing ECSs cannot have their specifications modified.
Image		ECSs created using ISO images cannot have their specifications modified.
Disk		The target specifications must support at least as many SCSI or VBD disks as those currently attached to the ECS. ECSs with disks being attached or detached cannot have their specifications modified.
Network interface		The target specifications must support at least as many network interfaces as those currently attached to the ECS. The target specifications must support at least as many supplementary network interfaces as those currently attached to the ECS. The target specifications must support at least as many vRoCE network interfaces as those currently attached to the ECS.
ECS type	CPU	The target specifications must support at least as many hyperthreads as those supported by the current specifications.
	GPU	GPU-accelerated ECSs using passthrough GPUs cannot have their specifications modified.
	FPGA	FPGA-accelerated ECSs cannot have their specifications modified.
	Local disk	ECSs using local disks cannot have their specifications modified.
	Snapshot	ECSs with snapshots cannot be resized to special flavors, for example, flavors with local disks or special memory (NVDIMM).
Feature	IPv6	ECSs with IPv6 enabled cannot be resized to specifications that do not support IPv6.
	QingTian Enclave	ECSs with QingTian Enclave enabled cannot be resized to specifications that do not support QingTian Enclave.
	ECS group	ECSs with failure domain policies configured cannot be resized to specifications that do not support ECS group fault domain policies.
	Recycle bin	ECSs in the recycle bin cannot have their specifications modified.
	Scheduled event	ECSs that have scheduled specification modification events generated cannot have their specifications modified.

Specification Modification Methods

When modifying specifications, you can change the vCPUs and memory as well as the virtualization type of ECSs.

ECSs support Xen, KVM, and QingTian virtualization types. The following table lists the scenarios and methods of modifying specifications.

**Table 2** Specification modification methods
Scenario		Reference	Description
Virtualization type not changed	Individual ECS	Modifying Specifications of Individual ECSs	Modify the specifications of one single ECS without changing the virtualization type.
Virtualization type changed	Change from Xen to KVM	Changing a Xen ECS to a KVM ECS (Windows)	Modify the specifications of an ECS with the virtualization type changed from Xen to KVM. In this scenario, you need to install related drivers first. Otherwise, the ECS will be unavailable, such as OS start failures, after the specifications are modified. You can select an appropriate operation guide based on the OS type and operation mode.
		Automatically Changing a Xen ECS to a KVM ECS (Linux)
		Manually Changing a Xen ECS to a KVM ECS (Linux)
		Automatically Changing Xen ECSs to KVM ECSs in a Batch (Linux)
	Change from KVM to QingTian	Changing a KVM ECS to a QingTian ECS (Windows)	Modify the specifications of an ECS with the virtualization type changed from KVM to QingTian. In this scenario, the disk drive letters and driver dependencies will change, so you need to check the startup dependencies and installed drivers first. Otherwise, the ECS will be unavailable, such as OS start failures, after the specifications are modified. You can select an appropriate operation guide based on the OS type.
	Change from KVM to QingTian	Changing a KVM ECS to a QingTian ECS (Linux)