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    Server Migration Center:Cross-zone ECS instance migration

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    Server Migration Center:Cross-zone ECS instance migration

    Last Updated:Sep 12, 2024

    Server Migration Center (SMC) allows you to migrate an Elastic Compute Service (ECS) instance across zones in a region and change the instance type at the same time based on your business requirements. The instance type specifies the number of vCPUs and the memory size and can be changed within the same instance family.

    Scenarios

    • Change the instance type of an ECS instance

      If the current configurations of your ECS instance cannot meet your business requirements and the required instance type is sold out in the current zone, you can change the instance type within the same instance family while migrating the ECS instance across zones.

    • Change the zone of an ECS instance

      You can deploy your application on ECS instances across different zones in a region to ensure that when a zone fails, services can be quickly switched to another zone to continue running. This improves the overall availability and stability of your system.

    Limits

    • Preemptible instances are not supported.

    • You must change the instance type of an ECS instance within the same instance family. For more information about instance families, see Overview of instance families.

    • The following instance families do not support instance type changes across zones:

      • 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

      • Instance families of the eighth generation, including g8ise, g8a, g8i, g8ae, g8y, c8a, c8i, c8ae, c8y, r8a, r8i, r8ae, and r8y

    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 the 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 codes

    After an ECS instance is migrated, its software authorization codes may change.

    IP address

    • 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.

    Number of refunds allowed

    You can refund an ECS instance up to three times. An instance type downgrade may result in a refund, which consumes the refund quota.

    Other

    • 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 the 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 ECS instance is migrated. You must add the ECS instance to the vServer group of the SLB instance. For more information, see the "Modify a vServer group" section of the Create and manage a vServer group topic.

    Billing

    • When you migrate an ECS instance, if you do not change its instance type, no fee changes are involved.

    • Otherwise, fees are changed 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.

    Preparations

    Note

    The cross-zone migration feature is commercialized, but the instance type change feature is available only to specific users. If you want to try the instance type change feature, submit a ticket. Your account will be added to the whitelist.

    • Create snapshots for the disks of the ECS instances to migrate. For more information, see Create a snapshot.

    • Make sure that the ECS instances are deployed in virtual private clouds (VPCs). If you want to change the instance type of an ECS instance that resides 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.

    • Make sure that applications 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.

    • 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 be installed and the instances cannot be started. 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 space. Otherwise, virtualization drivers may fail to be installed and the instances cannot be started.

    • Make sure that Alibaba Cloud Global Accelerator is disabled and the following items are not configured for the instances: IPv6 addresses, high-availability virtual IP addresses (HAVIPs), elastic network interfaces (ENIs), reverse proxies, and route tables.

    Procedure

    1. Log on to the SMC console.

    2. In the left-side navigation pane, choose Cloud Migration > Cross-zone Migration.

    3. In the upper-left corner of the page, click Cross-zone Migration.

    4. In the Cross-zone Instance Type Change dialog box, select instances, click Configure Parameters, configure the parameters in the Change Instance Type Across Zones dialog box, and then click OK.

      Parameter

      Description

      Instance to Be Migrated

      Select the ECS instances to be migrated.

      Preferred Destination Zone

      Select the zone to which you want to migrate the instances.

      Preferred Network Settings

      Select the 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 types based on your business requirements. Valid values:

      • Use Current Instance Type: Do not change the instance types.

      • Change Instance Type: Change the instance types. However, only partial instance families support instance type changes. For more information, see Instance types and families that support instance type changes.

        Important

        You can change an instance type only to another type within the same instance family.

      Note

      Select ECS Terms of Service and I have backed up data.

    5. Click OK.

    Verify the migration result

    • The migration is successful if the migration job enters the Completed state.

      imageAfter the cross-zone migration job is complete, perform the following operations to check the migration result:

      1. Click View Destination Instance in the Actions column of a migration source.

      2. On the Instance Details tab, view the Zone and Instance Type parameters of the migrated ECS instance.

    • The migration failed if the migration job enters the InError state.

      In this case, you need to perform the following operations:

      1. Click Troubleshoot Errors in the Actions column and fix the failure based on the error code and error message. For more information, see FAQ and Troubleshooting.

      2. On the Migration Jobs page, click Retry Migration Job.

        The migration job resumes from the point where it was suspended.