Change instance types across zones - Elastic Compute Service

Server Migration Center (SMC) allows you to change the instance types of Elastic Compute Service (ECS) instances across zones. This way, you can migrate ECS instances to different zones and change their instance types based on your business requirements.

Prerequisites

Note

The cross-zone instance type change feature is in invitational preview. To use the feature, submit a ticket.

The ECS instances use the subscription or pay-as-you-go billing method and are not preemptible instances.
The instance families to which the ECS instances belong support instance type changes. For information about ECS instance families that do not support instance type changes, see the Limits section of this topic.
Snapshots are created for the disks of the ECS instances. For more information, see Create a snapshot for a disk.
The ECS instances are deployed in virtual private clouds (VPCs). If you want to change the instance type of an ECS instance that is deployed in the classic network, you must migrate the instance from the classic network to a VPC. For more information, see Migrate ECS instances from the classic network to a VPC.
Applications that are deployed on the ECS instances do not depend on the current private IP addresses of the instances. If you select a new vSwitch when you change the instance type of an ECS instance across zones, the system assigns a new private IP address to the instance.
The ECS instances are not associated with IPv6 addresses or high-availability virtual IP addresses (HAVIPs) and do not have multiple elastic network interfaces (ENIs). Reverse proxies, route tables, and Alibaba Cloud Global Accelerator are not configured for the instances.

Scenarios

The instance types that are available in the current zone are insufficient. You want to change the instance types of instances to instance types that are available in a different zone within the same region.
You want to migrate ECS instances to a different zone within the same region based on your business requirements.

Limits

The following instance families do not support cross-zone instance type changes:
- Heterogeneous computing instance families
- ECS Bare Metal Instance families
- Super Computing Cluster (SCC) instance families
- u1, universal instance family
- e, economy instance family
- x86-based instance families:
  - Big data instance families
  - Instance families with local SSDs
  - Security-enhanced instance families
For information about instance families, see Overview of instance families.
If you want to change the instance type of an instance, the target instance type must belong to the same instance family as the original instance type.

Pre-migration notes

If security software such as Safedog, Huweishen, and Yunsuo is installed on the ECS instances whose instance types you want to change, disable the software before you make cross-zone instance type changes. Otherwise, virtualization drivers may fail to install and the instances cannot start. You can enable the software after the cross-zone instance type changes.
Make sure that the system disks of the ECS instances have more than 500 MiB of available disk space. Otherwise, virtualization drivers may fail to install and the instances cannot start.
During cross-zone instance type changes, do not stop, restart, or release the ECS instances manually or by using O&M scripts.
Each instance can be refunded up to three times. An instance type downgrade may result in a refund, which counts against the refund quota.

Migration impacts

Item	Description
Amount of time that is required to migrate an ECS instance	Approximately 15 minutes are required from the time when an instance is stopped until the time when the instance is migrated and started. Note After the computing and network resources of an ECS instance are migrated, the instance is started. After the instance is started, the system continues to migrate disk data of the instance. In most cases, approximately 4 hours are required to migrate 100 GiB of disk data. During the migration, the I/O performance of disks degrades and you cannot perform snapshot-related and disk-related operations.
Instance status	During the migration, the ECS instance is stopped and then restarted. We recommend that you migrate the instance during off-peak hours.
Software authorization code	After an ECS instance is migrated, its software authorization codes may change.
IP addresses	The public IP address of the ECS instance may change. After the instance is migrated, the system attempts to assign the original public IP address to the instance. If the original public IP address cannot be assigned to the instance, the system assigns a new public IP address to the instance. The private IP address of the ECS instance may change. After the instance is migrated, the new vSwitch assigns a new private IP address to the instance. You can modify the private IP address. For more information, see Modify the private IP address of an instance.
Fees	If you do not change the instance type of an ECS instance, you are not charged. If you change the instance type of an ECS instance, you are charged based on the following rules: If you downgrade the instance type of a subscription ECS instance, the instance type downgrade may result in a refund. The refund amount is calculated by using the following formula: Refund amount = Remaining amount of the configuration price before the downgrade - Price of the new configurations. If you upgrade the instance type of a subscription ECS instance, you must pay for the price difference between the original instance type and the new instance type for the remainder of the current billing cycle. Actual fees are displayed in the ECS console. If you change the instance type of a pay-as-you go ECS instance, you are charged based on the new instance type.
Others	After an ECS instance is migrated, the following attributes of the instance remain unchanged: instance ID, elastic IP address (EIP), media access control (MAC) address, security groups, disk serial numbers, disk IDs, username, and logon password. If an ECS instance is added to the vServer group of a Server Load Balancer (SLB) instance before the ECS instance is migrated, the ECS instance is not automatically associated with the SLB instance after the migration. You must add the ECS instance to the vServer group of the SLB instance. For more information, see the Modify a vServer group section in the "Create and manage a vServer group" topic.

Procedure

Note

The cross-zone instance type change feature is available only in the ECS console of the latest version.

Log on to the ECS console.
In the left-side navigation pane, choose Instances & Images > Instances.
In the top navigation bar, select the region and resource group to which the resource belongs.
Change the instance types of ECS instances based on your business requirements.
- To change the instance type of a single ECS instance, find the instance and click Change Configurations in the Actions column.
- To change the instance types of multiple ECS instances at the same time, perform the following operations:
  - On the Instance page, select the instances whose instance types you want to change and choose More > Upgrade/Downgrade > Change Configurations.
  - In the Change Configurations dialog box, confirm the instances and click Next.
On the Instance Configuration tab in the Change Configurations dialog box, select Change Instance Type Across Zones and click Continue.

In the Change Instance Type Across Zones dialog box, configure parameters and click OK.

The following table describes the parameters.

Parameter	Description
Migration Task Type	The value is fixed to ECS Instance Migration.
Current Region	The region in which the ECS instances reside is displayed.
Preferred Destination Zone	Select a destination zone based on your business requirements.
Preferred Network Settings	Select a destination vSwitch. After the instances are migrated, new private IP addresses that belong to the CIDR block of the vSwitch are randomly assigned to the instances. Important After the instance type of an instance is changed across zones, the original private IP address of the instance is not retained. Make sure that applications deployed on the instance do not depend on the original private IP address.
Instance Type	Specify whether to change the instance type based on your business requirements. Use Current Instance Type: Do not change the instance types. Change Instance Type: Change the instance types. For information about the instance families that support instance type changes across zones and other limits on instance type changes, see the Limits section of this topic.
Preferred New Instance Type	Select a target instance type. Note This parameter is displayed only if you select Change Instance Type.
Instance to Be Migrated	The information about the ECS instances is displayed in the Instance ID/Name, Destination Zone, Destination Instance Type, and Destination vSwitch columns.
Note	Select ECS Terms of Service and I have backed up data.

In the dialog box that appears, click Pay and complete the payment as prompted.
Go back to the ECS console to check the instance status.
A specific period of time is required to change the instance types. If the instance type of an ECS instance is changed, the state of the instance changes from Migrating to Running. You can check the progress of the cross-zone instance type change in the SMC console. Perform the following steps:
1. Log on to the SMC console.
2. In the left-side navigation pane, click Migration Jobs.
3. Click the Cross-zone Migration tab. Then, check the migration progress in the Status column corresponding to the instance. If the instance type is changed, the state of the migration job is Completed.