Move ECS Instances Across Servers Using SMC - Server Migration Center

Use Server Migration Center (SMC) to migrate ECS instances between accounts or across regions within the same account for various purposes, including business migration, insufficient regional inventory, cost optimization, and disaster recovery.

Note

You can also use the Copy Custom Image and Share Custom Image features of ECS to migrate ECS Instances between accounts or within the same account.

Use cases

You can migrate an Elastic Compute Service (ECS) instance in the following use cases:

Use case 1: Migrate an instance between different Accounts
In this use case, you migrate an ECS instance to a different Alibaba Cloud Account. This migration is supported both within the same Region and across different Regions.
Use case 2: Migrate an instance within the same Account
In this use case, you migrate an ECS instance within the same Alibaba Cloud Account, either to a different Region or Zone.
- If you have not purchased a Target Instance, you can convert the Source Server to a Custom Image and then use the Image to manually create a new ECS instance.
- If you have purchased a Target Instance, you can migrate the Source Server directly to it. Ensure that the Storage and Operating System of the Source Server are compatible with the Target Instance.
Use case 3: Shrink disks
Elastic Compute Service (ECS) does not support directly scaling down a System Disk or Data Disk. As a workaround, you can migrate the instance to a Custom Image or a Target Instance that has smaller disks. This method is supported for migrations within the same Account and across different Accounts. For more information, see Shrink disks.
Important
- For Linux servers, you can modify the disk size during migration only when Block Replication is disabled.
- For Windows servers, you must shrink the disk before migration.

Migration limits

Currently, you cannot migrate ECS instances created from Alibaba Cloud Marketplace images. To do so, contact us to be added to the whitelist.

Migration considerations

Before migrating, consider the following:

Consideration	Description
Migrated data directories	During migration, SMC automatically generates a destination disk partition structure that matches the source server's disk partition structure as closely as possible. You can adjust the destination disk's partition structure, including partition size, order, transfer method, and Logical Volume Management (LVM) configurations. By default, all disks on the server are migrated: If a data disk has no mount target, that data disk is not migrated. If you do not need to migrate certain partition directories, you can choose not to migrate them when you adjust the partition structure. For more information, see Adjust the disk partition structure as needed.
Intermediate instance	Do not interfere with the intermediate instance. To avoid migration failure, do not stop, start, restart, or release the intermediate instance during the migration. Do not change its billing method. After the migration is complete, the intermediate instance is automatically released. Note For each migration, SMC creates a pay-as-you-go temporary intermediate instance named `No_Delete_SMC_Transition_Instance` in your destination Alibaba Cloud account to assist with the migration. If you choose to migrate to a destination instance, that instance serves as the intermediate instance and is not automatically released. For more information, see How SMC works.
IP address	The IP address changes after migration, which may cause service interruptions. Migrate during off-peak hours. If your services involve IP address configurations, modify the domain name resolution and ICP filing information after the migration. If a domain name is mapped to the source server, map the domain name to the new server's public IP address. For more information, see Add a DNS record. To keep the private IP address unchanged, perform the following operations: Migrate to an ECS Image: After the migration, using the ECS image, specify the primary private IPv4 address of the primary network interface card when you purchase an ECS instance. Migration to an Elastic Compute Service Instance: You can modify the private IPv4 address of the target instance in the Advanced Configuration section of the Migration Settings step. You can also modify it after the migration. To retain the public IP address when migrating within the same region: If the source ECS Instance uses a static public IP address: Before migration, Convert the static public IP address of an ECS Instance to an EIP to retain the public IP address. After migration, disassociate the Elastic IP address (EIP) and then associate it with the destination ECS Instance. If the source ECS Instance uses an Elastic IP address (EIP): After migration, disassociate the EIP from the source ECS Instance and then associate it with the destination ECS Instance.
Underlying hardware devices	After migration, the underlying hardware devices change. This may invalidate some application licenses that are bound to hardware. Check your licenses.
Performance impact	The migration process consumes server resources, including CPU, memory, disk I/O, and network bandwidth.
Data consistency before and after migration	For information about data and system configuration changes that occur before and after migration, see Data consistency issues after migration.

Impact on web applications after server migration

After you migrate a server to Alibaba Cloud ECS, your business's network topology, computing and storage resources, application security settings, costs, monitoring, compatibility, network latency and bandwidth, backup and recovery, and operations and maintenance (O&M) processes will change. You must also consider the following aspects:

Impacted item	Description
Network connectivity	After migration, the ECS instance uses a new virtual private cloud (VPC). Its network location and other configurations change with the VPC migration. The ECS instance cannot directly communicate with the original network or other ECS instances in the VPC. To enable communication across accounts and VPCs, see VPC connections.
Security group	After migration, the ECS instance uses new security group rules to control inbound and outbound traffic. Changes to access rules may affect normal business access. If the destination account's security group does not have the necessary rules, you can quickly add them by exporting the rules from the original ECS instance's security group and importing them into the destination security group. For more information, see Import and export security group rules.
SSL Certificate	If your website uses HTTPS, you need to apply for and install an SSL Certificate. You can apply for a free SSL certificate from Alibaba Cloud and deploy it to your ECS instance. For more information, see Purchase and deploy an SSL certificate to an ECS instance.
Data migration	To migrate data from other servers to Alibaba Cloud, you can use methods such as FTP, SCP, or manual backup to OSS. For more information, see Transfer files to an ECS instance and Use ossutil to transfer data to an ECS instance.
Other configurations	Ensure that database connections, APIs, and Server Load Balancer (SLB) instances point to the new domain name and ECS IP address.

Preparations

Complete the pre-migration preparations for the server.
Read the migration guide to understand the SMC client, migration principles, billing, migration process, and feedback channels.
To prevent data loss, back up important data to an image, snapshot, or a storage device other than the instance before you start the migration.
When you migrate servers across international regions, the migration speed may be slow because of unstable public network conditions. You can estimate the migration time and test the transfer speed. We recommend that you connect your source server to the Alibaba Cloud VPC using a VPN Gateway, Express Connect circuit, physical connection, or Smart Access Gateway, and then migrate over the private network.
If you can directly access a VPC in an Alibaba Cloud region from your on-premises data center, VM environment, or cloud host, we recommend that you use the SMC private network migration solution. This solution is faster and more stable than migrating over the public network and improves migration efficiency.
To migrate a source server to a purchased Alibaba Cloud ECS instance:
- If the source server runs a Linux system, the destination instance must run a Linux distribution. If the source server runs a Windows system, the destination instance must run a Windows system.
- The number of data disks attached to the destination instance must be greater than or equal to the number of data disks on the source server. If the destination instance does not have enough data disks, you must attach data disks.
- The capacity of the system disk and data disks on the destination instance must be greater than or equal to the capacity of the system disk and data disks on the source server. If you want to reduce the disk size, the capacity of the system and data disks on the destination instance must be greater than or equal to the used capacity of the disks on the source server. If the disk capacity of the destination instance is insufficient, you must resize the disks.

Migration procedure

Step 1: Import the migration source

Console

Cross-account

For a cross-account migration (from source account A to target account B), log on to the Resource Access Management (RAM) console with source account A to create a role. Then, log on to the Server Migration Center (SMC) console with target account B.

Warning

In a cross-account migration, carefully distinguish between source account A and target account B to avoid a reverse migration.
When you import the migration source, you must use a Resource Access Management (RAM) user that belongs to target account B.

Prerequisites

An Elastic Compute Service (ECS) instance exists in the source account.
The source server must be in the Running state, and the Cloud Assistant client must be running properly. For more information, see View Cloud Assistant client status and troubleshoot exceptions.

Preparations

A cross-account migration from the console requires a Resource Access Management (RAM) user. Before you begin, log on to the target account and grant the following permissions to this RAM user:
If no RAM user exists under the Alibaba Cloud account, create one first.
- AliyunSTSAssumeRoleAccess: Grants permission to call Security Token Service (STS) operations.
- AliyunSMCFullAccess: Grants full management permissions on Server Migration Center (SMC).
- AliyunECSReadOnlyAccess: Grants read-only permissions on Elastic Compute Service (ECS).
- AliyunECSAssistantFullAccess: Grants full management permissions on Cloud Assistant.
Follow these steps to grant the AliyunSTSAssumeRoleAccess permission.
1. Log on to the Resource Access Management (RAM) console with the target Alibaba Cloud account.
2. In the navigation pane on the left, choose Identities > Users and click the logon name of the target user.
3. Choose Permissions > Add Permissions.
4. On the Add Authorization page, enter AliyunSTSAssumeRoleAccess, then select the corresponding policy and click Confirm New Authorization.
Record the account IDs of both the source and target Alibaba Cloud accounts.
1. Log on to the Alibaba Cloud console with the source and target accounts.
2. Hover over the profile icon in the upper-right corner to view the account ID.

Procedure

Log on to the Resource Access Management (RAM) console with the source account (Account A) to create a role and grant permissions.
1. Select Permission Management > Permission Policy, and click Create Permission Policy. On the Script Edit tab, add the policy and click OK. Enter policy-smc as the policy name.
```
{
    "Version": "1",
    "Statement": [
        {
            "Action": [
                "ecs:DescribeZones",
                "ecs:DescribeInstances",
                "ecs:DescribeSecurityGroupAttribute",
                "ecs:DescribeSecurityGroups",
                "ecs:DescribeSnapshots",
                "ecs:DescribeImages",
                "ecs:DescribeDisks",
                "ecs:DescribeCloudAssistantStatus",
                "ecs:RunCommand",
                "ecs:DescribeInvocations"
            ],
            "Resource": "*",
            "Effect": "Allow"
        }
    ]
}
```
2. Select Identity Management > Role, and click Create Role. For Trusted Entity Type, select Cloud Account. For Trusted Entity Name, select Other Cloud Account and enter the ID of the target Alibaba Cloud account (Target Account B). Enter ram-role-smc as the target role name and click OK.
3. Click the role name ram-role-smc, and on the details page of the target role, click Permission Management > Precise Authorization, select Custom Policy, enter the policy name policy-smc, and click OK.
Log on to the Server Migration Center (SMC) console as the target account's Resource Access Management (RAM) user.
On the Cross-account/Same-account Migration page, click Import Migration Source.

Configure the parameters as prompted on the page and copy the activation code command. The following table describes the parameters.

Parameter	Description
Migration source type	Alibaba Cloud ECS server.
Import method	Select Console Import. This authorizes SMC to remotely connect to the source server from the console to automatically import the migration source. The import process automatically invokes Cloud Assistant. Do not interrupt or exit the process.
Cross-account migration	Cross-account.
Alibaba Cloud account of source server	Enter the ID of the Alibaba Cloud account that owns the source server (Account A).
Role in source server's account	Enter the role created in Step 1 (`ram-role-smc` in this example).
Region	Select the region where the source server is located.
Instance	Search for and select the source ECS instance in the specified region by its instance ID, name, or IP address. You can select multiple instances for batch import.

After you configure the parameters, click Import.
SMC automatically starts the Cloud Assistant client for the import, which takes 3 to 10 minutes.
On the Cross-account/Same-account Migration page in the Server Migration Center (SMC) console, view the status of the migration source in the Migration Real-time Status column.
- If the status is Migration Source Online, the import succeeded.
  Note
  In a cross-account ECS instance migration, the public IP address of the migration source may not be displayed, the operating system information may be incomplete, and the instance status may not be recognized. This is normal and does not affect the migration task.
- If the source shows any other status, the import failed. Troubleshoot the issue and then try to import the source again.
  - You can troubleshoot the issue based on the error message on the console or by checking the SMC client log files. The default installation directories are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For common issues and solutions, see SMC FAQ and Troubleshooting.

Same-account

Important

The source Elastic Compute Service (ECS) instance must have a public IP address.
The source server must be in the Running state, and the Cloud Assistant client must be running properly. For more information, see Check the status of the Cloud Assistant client and handle exceptions.
If you use a Resource Access Management (RAM) user to import the migration source, you must grant permissions to the RAM user:
- Grant the AliyunECSReadOnlyAccess permission for read-only access to ECS.
- Grant the AliyunECSAssistantFullAccess permission for full management permissions on Cloud Assistant.

Go to the Server Migration Center (SMC) console.
On the Cross-account/Same-account Migration page, click Import Migration Source.

Configure the parameters as prompted on the page and copy the activation code command. The following table describes the parameters.

Parameter	Description
Migration source type	Alibaba Cloud ECS server.
Import method	Select Console Import. This authorizes SMC to remotely connect to the source server from the console to automatically import the migration source. The import process automatically invokes Cloud Assistant. Do not interrupt or exit the process.
Cross-account migration	Same-account.
Region	Select the region where the source server is located.
Instance	Search for and select the source ECS instance in the specified region by its instance ID, name, or IP address. You can select multiple instances for batch import.

After you configure the parameters, click Import.
SMC automatically starts the Cloud Assistant client for the import, which takes 3 to 10 minutes.
In the Real-time Migration Status column on the Cross-account/Same-account Migration page of the Server Migration Center (SMC) console, view the status of the migration source.
- If the status is Migration Source Online, the import succeeded.
  Note
  In a cross-account ECS instance migration, the public IP address of the migration source instance may not be displayed. The operating system information may be incomplete, and the instance status may be unrecognizable. This is normal and does not affect the migration task.
- If the source shows any other status, the import failed. Troubleshoot the issue and then try to import the source again.
  - You can troubleshoot the issue based on the error message on the console or by checking the SMC client log files. The default installation directories are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For common issues and solutions, see SMC FAQ and Troubleshooting.

CLI (Recommended)

Important

The source server must have a public IP address. If the source server has firewall restrictions, see SMC service endpoints to find the required SMC domain names and ports, and add them to the firewall allowlist.
If your source server cannot access the internet or you want to use a private network for higher efficiency, see Private network migration.

Obtain the activation code command.

Depending on your migration scenario, log on to the Server Migration Center (SMC) console.
- For a same-account migration, log on to the SMC console with the Alibaba Cloud account that owns the source ECS instance.
- For a cross-account migration (from source account A to target account B), log on to the SMC console with target account B.
  Warning
  - In a cross-account migration, carefully distinguish between source account A and target account B to avoid a reverse migration.
  - When you import the migration source, you must provide the activation code or AccessKey pair of target account B.
On the Cross-account/Same-account Migration page, click Import Migration Source.

Configure the parameters as prompted on the page and copy the activation code command. The following table describes the parameters.

Parameter	Description
Migration source type	Alibaba Cloud ECS Server.
Import method	Select Command-Line Import.
Migration source quota	The number of migration sources that can be activated with the activation code. The value ranges from 1 to 1,000. The default is 200.
Validity period	The validity period of the activation code. The value ranges from 1 to 90 days. The default is 90 days.
Activation code	After generating the activation code, copy the command. Follow these steps: Click Generate. Based on the source server's operating system, click the Linux Shell or Windows Powershell tab. Click Copy to copy the activation code command.

Log on to the source server, and then paste and run the copied command with administrator privileges to import the migration source.
Linux source server
1. Log on to the Linux source server.
2. Paste and run the copied command with administrator privileges to import the migration source.
  A message similar to Import Source Server [s-bp18x8751kgz2oyh****] Successfully! appears. This indicates that the migration source was imported successfully.
Windows source server
1. Log on to the Windows source server.
2. Open Windows PowerShell as an administrator.
3. Paste and run the copied command to import the migration source.
  A message similar to Import Source Server [s-bp19rlidl3mwuptc****] Successfully! appears. This indicates that the migration source was imported successfully.
  If the command fails to run, see What do I do if the command fails when I import a Windows migration source from the command line?.
In the Real-time Migration Status column on the Cross-account/Same-account Migration page of the Server Migration Center (SMC) console, view the status of the migration source.
- If the status is Migration Source Online, the import succeeded.
  Note
  In a cross-account ECS instance migration, the public IP address of the migration source may not be displayed, the operating system information may be incomplete, and the instance status may not be recognized. This is normal and does not affect the migration task.
- If the source shows any other status, the import failed. Troubleshoot the issue and then try to import the source again.
  - You can troubleshoot the issue based on the error message on the console or by checking the SMC client log files. The default installation directories are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For common issues and solutions, see SMC FAQ and Troubleshooting.

SMC client

For more information about the SMC client, see SMC Client User Guide.

Important

The client must run on the source server. By default, the client accesses SMC over the internet. If the source server has firewall restrictions, see SMC service endpoints to find the required SMC domain names and ports, and add them to the firewall allowlist.
If your source server cannot access the internet or you want to use a private network for higher efficiency, see Private network migration.

Based on the migration scenario, use the appropriate Alibaba Cloud account to go to the Server Migration Center (SMC) console.
- For a same-account migration, log on to the SMC console with the Alibaba Cloud account that owns the source ECS instance.
- For a cross-account migration (from source account A to target account B), log on to the SMC console with target account B.
  Warning
  - In a cross-account migration, carefully distinguish between source account A and target account B to avoid a reverse migration.
  - When you import the migration source, you must provide the activation code or AccessKey pair of target account B.
在跨账号/同账号迁移页面，单击导入迁移源。

On the Import Migration Source page, configure the parameters described in the following table.

Parameter	Description
Migration source type	Alibaba Cloud ECS server.
Import method	Client Import
Description	In the Import Instructions area, follow the prompts to download, install, and activate the corresponding SMC client based on the source server's operating system (Linux or Windows) and architecture (32-bit or 64-bit). Click Generate Activation Code and copy the activation code information. You must enter the activation code when you install the client.

Import the migration source.
Important
Do not close the SMC client during the migration. Otherwise, the migration source disconnects from the SMC console, causing the migration to fail.
Windows
1. Use a remote connection tool that supports file transfers, such as WinSCP, to upload the downloaded SMC client to the Windows source server.
2. On the Windows source server, use the built-in decompression tool or a third-party tool to extract the SMC client package.
3. In the SMC client folder for your system version, double-click the go2aliyun_client.exe application.
  You will be prompted for administrator permissions at runtime. Click OK.
4. Obtain an activation code or an AccessKey pair.
  - (Recommended) Obtain an activation code: In the Import Instructions section of the Server Migration Center (SMC) console, click Generate Activation Code and copy the activation code information.
  - Obtain an AccessKey pair: An AccessKey pair for an Alibaba Cloud account consists of an AccessKey ID and an AccessKey secret. If you have not created one, create an AccessKey pair first.
5. As prompted, enter the values for the activation code, access_access_token_id and access_token_code, and press the Enter key.
  When a message similar to Import Source Server [s-bp18x8751kgz2oyh****] Successfully! is returned, it indicates that the migration source has been successfully imported.
Linux
1. Use a remote connection tool that supports file transfers, such as WinSCP, to upload the downloaded SMC client to the Linux source server.
2. Remotely connect to the Linux source server and extract the SMC client package.
  This example uses the Linux 64-bit universal version. If you use a different version of the SMC client, you need to replace the compressed package name in the command with the actual name of the downloaded file.
```
tar -zxvf go2aliyun_client.tar.gz
```
  Note
  Linux 64-bit (ARM) supports the general-purpose instance type family g6r and the compute-optimized instance type family c6r. For more information about instance types, see Enterprise-level ARM Compute Instance Families.
3. (Optional) You can filter and exclude files or directories that you do not want to migrate.
4. Obtain an activation code or an AccessKey pair.
  - (Recommended) Obtain an activation code: In the Server Migration Center (SMC) console, under Import Instructions, click Generate Activation Code and copy the activation code information.
  - Obtain an AccessKey pair: An AccessKey pair for an Alibaba Cloud account consists of an AccessKey ID and an AccessKey secret. If you have not created one, create an AccessKey pair first.
5. In the SMC client folder, run the following commands to start the SMC client.
```
cd go2aliyun_client_linux_x86_64
sudo chmod +x go2aliyun_client
sudo ./go2aliyun_client
```
6. As prompted, enter the activation code or AccessKey pair. This example uses an activation code:
  After you enter the credentials, you may see the following prompts:
  - If the snapshot driver is not installed on the source system, the SMC client displays a prompt.
    Enter no because you must disable block replication to scale down and migrate a Linux server.
    Important
    If the snapshot driver fails to install, do not enable block replication when you create the migration task. Otherwise, the migration fails.
  - Rsync is installed by default on most mainstream migration source systems. If it is not installed, the SMC client will prompt you. Enter yes to automatically install rsync.
  - If SELinux is enabled on the migration source system, the SMC client prompts you to disable it. Enter yes to automatically disable SELinux.
  When a message similar to Import Source Server [s-bp11npxndknsycqj****] Successfully! is returned, it indicates that the migration source is successfully imported.
  Note
  If the import fails, troubleshoot the issue based on the displayed message, and then run the following commands to exit the background process and re-import the source. For more information about common issues and solutions, see SMC FAQ and Troubleshooting.
  sudo ./go2aliyun_client --abort sudo ./go2aliyun_client
On the Cross-account/Same-account Migration page of the Server Migration Center (SMC) console, view the status of the migration source in the Migration Real-time Status column.
- If the status is Migration Source Online, the import succeeded.
- If the source shows any other status, the import failed. Troubleshoot the issue and then try to import the source again.
  - You can troubleshoot the issue based on the error message on the console or by checking the SMC client log files. The default installation directories are:
    - Windows source server: C:\smc.
    - Linux source server: /smc.
  - For common issues and solutions, see SMC FAQ and Troubleshooting.

Step 2: Migration configuration

Find the migration source that you want to manage and click Start Migration in the Actions column.

Configure the parameters and click Start Migration.

Configure basic parameters.

Parameter	Description
Destination Type (Required)	Select the destination type based on your migration scenario: ECS Image Convert the existing source server into an ECS custom image, and then use that custom image to create a new ECS instance to complete the migration. The following table describes the configuration items: Destination Region: The Alibaba Cloud region to which you want to migrate your source server. This parameter is required. For more information about regions, see Regions and zones. Image Name Prefix: The name of the destination Alibaba Cloud custom image that SMC generates for the migration source. ECS Instance Migrate the source server directly to a purchased ECS instance. The storage, operating system, and other configurations of the source server and the purchased ECS instance must be compatible. Important When migrating to a destination instance, the operating system of the destination instance is replaced first. Automatic snapshots of the system disk are cleared and cannot be recovered. To retain automatic snapshots for future use or data security, you can manually disable the automatic release of snapshots with the disk before migration. For more information, see Configure automatic snapshots to be released with disks. The following table describes the configuration items: Destination Region: The Alibaba Cloud region to which you want to migrate your source server. This parameter is required. For more information about regions, see Regions and zones. Destination Instance: Select an ECS instance as the destination instance.
Migration Drill	The migration drill feature helps you understand the feasibility and risks of a migration task before the actual migration. It provides information such as data volume, migration speed, and total migration time, and offers repair suggestions to reduce potential problems and losses during the actual migration. Pay-as-you-go resources will incur some fees during the migration drill. By default, Migration Drill is enabled. Warning If the destination type is ECS Instance, snapshots will be created for all disks of the destination ECS instance during the migration drill. If the drill is abnormal or the execution mode is Drill Only, the snapshots will be automatically rolled back after the migration drill is complete. The destination ECS instance will be unavailable during the migration drill, and data will be lost. Ensure that the destination ECS instance does not contain important data. For more information, see Configure a migration drill.
Execution Mode	Select an execution mode based on whether Migration Drill is enabled: If Migration Drill is enabled Drill Only: Creates only a migration drill task. After the drill is complete, you must manually start the server migration task if you want to migrate the server. Drill and Migrate: After the migration drill is complete, the system automatically starts the server migration task if there are no drill items with a Critical status. Drill and Migrate is selected by default. If Migration Drill is not enabled Migrate Now: Starts the migration immediately after creating the migration task. Migrate Now is selected by default. Schedule Migration: Creates a migration task that automatically starts at a set time. Note The earliest scheduled execution time can be set to 10 minutes from the current time. Create Only: Creates only a migration task. You must later manually start the migration task by clicking Start Migration in the Actions column.
Automatic Incremental Synchronization	Specifies whether the migration task automatically synchronizes incremental data from the source server to Alibaba Cloud. By default, automatic incremental synchronization is disabled. If you enable this switch, you need to set the following configuration items: Sync Repeat Frequency: The time interval at which the incremental migration task is automatically executed periodically. Max Image Retention: The maximum number of images that the incremental migration task retains by default. The migration task will run periodically and synchronize incremental data to Alibaba Cloud. For best practices on incremental migration, see Incremental server migration. If you disable this switch, the migration task runs only once.
Enable Migration Template	This parameter appears only when Destination Type is set to ECS Image. Migration templates are used to preset migration task parameters. When you start a migration, the template parameters are automatically filled in. For more information about setting a migration template, see Set a migration template.
Network Mode	Select the network to use for transferring migration data to the intermediate instance. By default, public network transmission is used. The intermediate instance is created in the selected virtual private cloud (VPC) and vSwitch, so it is assigned a public IP address. Public Network Transmission (Default) Migration data is transferred to the intermediate instance over the public network. This mode requires the source server to have public network access. As needed, choose whether to specify a VPC and a vSwitch. Specify a VPC and vSwitch: The migration task creates an intermediate instance in your specified VPC and vSwitch. Do not specify a VPC and vSwitch: The migration task creates an intermediate instance in a system-generated VPC and vSwitch. Private Network Transmission Migration data is transferred to the intermediate instance over the VPC's internal network. This mode requires you to connect the source server to the Alibaba Cloud VPC and specify a VPC and vSwitch. Note If you can directly access a VPC in an Alibaba Cloud region from your on-premises data center, VM environment, or cloud host, we recommend using this migration method. Using the internal network provides faster and more stable data transmission than the public network, improving migration efficiency. You can connect the source server to the cloud VPC using a VPN Gateway, Express Connect circuit, physical connection, or Smart Access Gateway. For more information, see Connect a VPC to an on-premises data center or another cloud.
Destination Instance IPv4 Private Address	To change the private IP address of the destination instance, you can manually specify a private IP address. This parameter appears only when Destination Type is set to ECS Instance. Keep Unchanged: By default, the migration IP address of the destination instance remains unchanged. Manually Specify: Allows you to enter an address within the available IP CIDR block of the vSwitch where the destination instance is located. When the migration source's IP address is in the vSwitch's CIDR block, you can change the destination instance's IP address to the migration source's IP address. When the destination instance's CIDR block is the same as the migration source's: Directly enter the private IP address of the migration source. When the destination instance's CIDR block is different from the migration source's: You first need to change the VPC of the destination instance so that their CIDR blocks are the same, and then enter the private IP address of the migration source.

Adjust the disk partition structure as needed. The following table describes the parameters.

Parameter

Description

Adjust Disk Partition Structure

Choose whether to enable adjusting the disk partition structure based on your needs. This feature is supported only in SMC client V2.8.0 and later. For more information about the SMC client, see SMC client user guide.

Disabled: The source instance's disk information is not displayed. The system automatically reads the source instance's disk information and generates a disk structure. After migration, the destination disk partition structure will be consistent with the automatically generated structure by default.
Enabled: The source instance's disk information is displayed. The system automatically reads the source instance's disk information and generates a disk structure. You can adjust the destination disk partition structure, including partition size and order, transfer method, and whether to enable LVM.
The following table describes the disk partition structure parameters:
Configure disks
System Disk: The size of the destination Alibaba Cloud server's system disk, in GiB. The system disk size ranges from 20 to 2,048.
The destination system disk size must be larger than the actual used space of the source system disk. For example, if the source system disk is 400 GiB and 100 GiB is used, the destination system disk size must be greater than 100 GiB.
Note
The default value is the size of the source system disk. If you do not need to reduce the system disk capacity, we recommend not setting it to a value smaller than the default.
Data Disk <N>: The size of the destination Alibaba Cloud server's data disk, in GiB. The data disk size ranges from 1 to 32,768.
The variable <N> represents the data disk number. If migrating to a destination instance, N is the data disk ID.
The data disk size must be larger than the actual used space of the source data disk. For example, if the source data disk is 500 GiB and 100 GiB is used, the destination data disk size must be greater than 100 GiB.
If the Data Disk has no mount target or all mount targets are set not to be migrated, the data disk will not be migrated.
LVM: Logical Volume Management (LVM) is a mechanism for managing disk partitions in Linux systems. LVM is more flexible than standard disk partitions and allows for dynamic adjustment of disk space.
You can choose whether to enable LVM based on your needs. If LVM is enabled, the destination will automatically rebuild the disk with an LVM structure.
The following is an example:
For each destination disk with LVM enabled, the system creates one physical volume (PV) and its corresponding volume group (VG). On this VG, it creates a number of logical volumes (LVs) equal to the number of mount targets. The VG name defaults to vgX (where X is the disk's sequence number), and the LV name defaults to lvX (where X is the LV's sequence number). For example:
Important
LVM is not supported:
You cannot enable LVM if the migration source is a Windows system.
LVM requires a boot partition on the system disk.
After enabling LVM, the feature will not take effect in the following scenarios:
The migration source does not support lvm2 or the lvm2 package is not installed.
The migration source is a Debian system with a kernel version of 3.x or earlier, and has a disk with an XFS file system mounted.
Configure mount targets
Migrate: You can choose whether to migrate the mount target based on your business needs.
Enable block replication: Using block replication can effectively improve the stability of migration transfer speed and ensure consistency with the source partition structure, but the partition size cannot be modified. SMC determines whether to support enabling block replication based on the state of the source disk partition.
If the source partition does not support enabling block replication, the switch cannot be turned on. The default file replication is used, and the partition size can be modified.
If the source partition supports enabling block replication, block replication is enabled by default to achieve partition-level disk migration.
Note
When the migration source is a Windows operating system, the block replication feature is enabled by default and cannot be disabled.
If LVM is enabled on the disk and the partition size is not an integer multiple of 4 MiB, block replication will not take effect, and file replication will be used for data transfer.
Set partition size: When block replication is not enabled, you can set the partition size as needed, but the sum of partition sizes cannot exceed the size of the belonging disk.
Note
If the disk sizes of the destination instance do not match the source disks, the task cannot be created. In this case, the system automatically adjusts the mount target positions to meet the disk size requirements. If the requirements are still not met after adjusting the mount targets, resolve the issue based on the interface prompts.
You can also manually drag and drop mount target positions to meet the disk size requirements. However, boot partitions or system partitions cannot be dragged. Follow these steps:
Hover your mouse over the icon in front of the mount target.
Drag the mount target to another disk with your mouse.

To set advanced parameters, such as the network mode, private IP address, or transfer speed limit, click Advanced Configuration. The following table describes the parameters.

Note

We recommend that you select VPC for Network Type. Migrating over a private network is faster and more stable than migrating over the internet.

Parameter	Description
Task Name	The name of the migration task.
Task Description	Enter a description for the migration task.
Transfer Speed Limit	The transfer speed limit restricts the actual network transfer speed, in Mbps. If the Compression Ratio is set to a value greater than 0, the actual network transfer speed (the speed of compressed data transfer) will be less than the speed displayed in the Real-time Migration Status.
Compression Ratio	The level of data compression during migration. Set the compression ratio based on your actual needs. In environments with limited bandwidth, using a high compression ratio can increase data transfer speed. In environments with very high bandwidth, we recommend not compressing data to reduce the CPU resource consumption on the source server. The value ranges from 0 to 10. The default is 7. A value of 0 means no data compression.
Checksum Verification	Disabled by default. Enabling it enhances data consistency verification but may reduce transfer speed.
SSL Encrypted Transmission	The default is Auto Select. Using Secure Sockets Layer (SSL) encryption for data transmission can improve data security and ensure data integrity.
License Type	Select the license type. Alibaba Cloud (Default): Currently only supports Microsoft Windows Server licenses. When you create an ECS instance from the image in Hong Kong (China) or other regions outside China, you will be charged an image license fee, and the license will be automatically activated. The specific fee is subject to the information displayed when creating the instance. Bring Your Own License: Bring Your Own License (BYOL) migration to the cloud currently includes Microsoft, Red Hat Enterprise Linux, and SUSE Linux Enterprise Server. When you create an ECS instance from the image after migration, you will not be charged an image license fee. Please use your own license for activation. Note If you have already created an ECS instance, Alibaba Cloud supports quickly purchasing software licenses such as Red Hat Enterprise Linux and SUSE Linux Enterprise Server for the specified ECS instance. For more information, see Purchase a software license for an ECS instance.
Image Detection	The image detection feature mainly checks whether an image is valid and whether it can be used to create a fully functional ECS instance. You can use the image detection feature when creating server migration and VMware agentless migration tasks. Image detection helps you quickly identify potential problems with the image or instance after migration and provides repair solutions to make it compliant with Alibaba Cloud standards, improving the success rate of instance startup. For more information, see Configure image detection.
Tags	Bind tag key-value pairs to the migration task for easy querying and management. For more information, see Use tags to manage migration sources and tasks and Implement fine-grained permission management using tags. Note A single migration task can be bound with up to 20 tags.
Intermediate Instance Type	You can select an intermediate instance type based on your actual needs. This parameter appears only when Destination Type is set to ECS Image. If you specify this parameter, the system will use this instance type to create the intermediate instance. If this instance type is out of stock, the migration task creation will fail. If you do not select an intermediate instance type, the system will select an instance type to create the intermediate instance. Important To avoid migration errors, do not stop, start, restart, or release the intermediate instance during the migration process. After the migration is complete, the instance is automatically released.
Upload Diagnostic Logs	Automatically upload SMC client logs to the SMC server-side for error diagnosis and analysis, which helps locate problems when migration errors occur. This feature is enabled by default. SMC client logs are generally saved in the `/smc/go2aliyun_client*/Logs` directory under the installation directory.

In the message that appears, read the migration notes and click Got It.
On the Cross-account/Intra-account Migration page, view the real-time status of the migration.
If you enabled Migration Drill, SMC performs the drill first. Transfer time depends on factors such as data volume and network bandwidth. Please wait patiently for the migration task to complete.
Note
- Speed: The amount of migration data transferred per second (i.e., the transfer speed of data before compression). If you set the Compression Ratio to a value greater than 0 when you create a migration task, the displayed speed will be greater than the actual network transfer speed (i.e., the transfer speed of data after compression).
- Remaining Sync Time: Remaining Sync Time = (Total Data Volume - Transferred Data Volume) / Speed.
- If the transfer speed is too slow, you can consider temporarily increasing the fixed bandwidth of the source and destination servers. For more information, see Estimate migration time and test transfer speed.
Subscribe to migration error events, modify the migration, and pause the migration
- To prevent errors from interrupting migration tasks, you can subscribe to SMC migration task error event notifications in CloudMonitor to receive timely email alerts.
- When the migration task is in the Syncing state, you can perform the following operations as needed:
  Edit the migration task: In the Actions column, click Modify Migration to change parameters such as Transfer Speed Limit, Compression Ratio, and Checksum Verification.
  Pause the migration task: In the Actions column, click Pause Migration.
(Optional) View migration details.
In the Source ID/Name column for the migration source, click the source ID to view the migration details.

Verify the migration result

A migration is successful when its Migration Status is Completed.
- If you set Destination Type to ECS Image:
  After the migration is successful, a custom Alibaba Cloud image is created. You can scroll to the right and in the Migration Deliverable column, click View Report to view the image detection results. For more information, see View image detection results.
  (Recommended) Manually verify the migration result
  In the Actions column, click Create Instance. You are redirected to the instance creation page in the ECS console with the custom image pre-selected. For more information, see Create an instance using a custom image or a shared image.
  Automatically verify the migration result
  Note
  To use this feature, you need to install the Cloud Assistant plugin on the instance, and the instance's operating system version must support the plugin. For more information, see Install Cloud Assistant Agent.
  This feature uses the Alibaba Cloud-provided OOS template ACS-SMC-CreateAndVerifyInstance to automatically verify whether an ECS instance can be created from the image generated by the migration task and start as expected.
  In the Actions column, click Verify Migration Result.
  In the dialog box that appears, review the verification process and click Verify Now.
  You can also click Customize Verification Script Parameters to manually configure verification parameters.
  View the verification result in the Verify Migration Result column.
  Verification Passed: The migration is valid. You can click Details to view the verification details.
  Verification Not Completed: Indicates that the migration result is abnormal. You can click View Reason to find the cause of the error and troubleshoot the problem.
  You can also click in the Actions column and then click Go to OOS to View Historical Verifications to view the execution history of the OOS template.
- If you set Destination Type to ECS Instance, you can click View Destination Instance in the Actions column to view the details of the destination ECS instance.
After you migrate the server, perform the following operations to ensure that your business runs as expected:
- Perform data validation and verification to ensure data integrity and correctness. For more information, see How do I check the system after migrating a Linux server? or How do I check the system after migrating a Windows server?.
- If applications and services on the source server are not set to auto-start, you must manually start them after the migration.
- The IP address changes after the migration. If your business involves IP address configurations, you must modify the domain name resolution, ICP filing, and other settings after the migration.
  If a domain name is mapped to the source server, map the domain name to the public IP address of the destination server. For more information, see Add a DNS record.
  If you want to keep the original private IP address, you can manually modify it after the migration is complete.
  Migrate to an ECS Image: You can modify the private IP address when you create an ECS instance. For more information, see Specify the primary private IPv4 address for the primary NIC when creating an ECS instance.
  Migrate to an ECS Instance: If you do not modify the private IPv4 address in the advanced configuration during the migration settings step, you can modify it after the migration is complete. For more information, see Modify the primary private IPv4 address of the primary NIC for an existing instance.
If Error is displayed in the Real-time Migration Status column, the migration failed.
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 Errors occurred during a server migration.
2. In the migration source list, click Retry Migration Job.
  The migration job resumes from the point where it was suspended.
  Important
  If the intermediate instance is released, you must create another migration job. For more information, see the What do I do if I accidentally release an intermediate instance? section of the "FAQ" topic.
If the Real-time Migration Status is Error, the migration task has encountered an error.
In this case, you must troubleshoot the issue and retry the migration:
1. In the Actions column, click Troubleshoot Error and resolve the issue based on the error code and error message. For more information, see SMC FAQ and Troubleshoot errors.
2. After fixing the problem, click Retry Migration in the Actions column. The system will resume the migration from where it left off.
  Important
  If the intermediate instance has been released, you must start a new migration. For more information, see What do I do if I accidentally release an intermediate instance?.

Clean up resources

Migrate to an ECS image

During the migration, SMC creates a temporary pay-as-you-go intermediate instance named No_Delete_SMC_Transition_Instance in your destination Alibaba Cloud account to assist with the migration. Whether you need to manually clean up the instance depends on the migration result:

Migration successful: The intermediate instance is automatically released. You do not need to clean it up manually.
Migration error: The intermediate instance persists with the migration task and incurs charges. You can release it in one of the following ways to avoid unnecessary charges:
- If you no longer need this migration task, click the source ID, and then in the Actions column, click Cancel Migration. This action deletes the migration task and automatically cleans up the intermediate instance.
- Manually release the intermediate instance.

Migrate to an ECS instance

During the migration, SMC creates a temporary pay-as-you-go intermediate disk named SMC_Temp_Disk under the destination instance to assist with the migration. Whether you need to manually clean up this intermediate disk depends on the migration result:

Migration successful: The intermediate disk is automatically released. You do not need to clean it up manually.
Migration error: The intermediate disk persists with the migration task and incurs charges. You can release it in one of the following ways to avoid unnecessary charges:
- If you have confirmed that a migration task is no longer needed, click its source ID. In the Actions column for the task, click Cancel Migration. This action deletes the migration task and automatically cleans up the intermediate disk.
- Manually release the intermediate disk.

References

To migrate incremental data multiple times, you can perform multiple incremental migrations at custom intervals after the initial full migration is complete. This synchronizes the incremental data generated on the source server to Alibaba Cloud, which reduces business downtime and the final cutover time. For more information, see Incremental server migration.
For more information about common issues and solutions, see FAQ and Troubleshooting.

Server Migration Center:Migrate ECS instances between accounts

Use cases

Migration limits

Migration considerations

Preparations

Migration procedure

Step 1: Import the migration source

Console

Cross-account

Prerequisites

Preparations

Procedure

Same-account

CLI (Recommended)

Linux source server

Windows source server

SMC client

Windows

Linux

Step 2: Migration configuration

ECS Image

ECS Instance

If Migration Drill is enabled

If Migration Drill is not enabled

Public Network Transmission (Default)

Private Network Transmission

Configure disks

Configure mount targets

Verify the migration result

(Recommended) Manually verify the migration result

Automatically verify the migration result

Clean up resources

Migrate to an ECS image

Migrate to an ECS instance

References