Migrate ECS instances across accounts or within the same account - Server Migration Center

You can use Server Migration Center (SMC) to migrate an Alibaba Cloud ECS instance from one account to another or across regions within the same account. Common reasons for migration include business relocation, insufficient regional resources, cost optimization, and disaster recovery.

Note

Alternatively, you can migrate ECS instances between accounts or within the same account using the ECS features to copy a custom image and share a custom image.

Migration scenarios

The following scenarios describe how to migrate Alibaba Cloud ECS instances:

Scenario 1: Migrate an instance from Account A to Account B
This scenario applies to migrating ECS instances between different Alibaba Cloud accounts. You can migrate instances to the same region or to a different region.
Scenario 2: Migrate an instance within the same account
This scenario applies to migrating ECS instances within the same Alibaba Cloud account. You can migrate instances across regions or zones.
- If you have not purchased an ECS instance, you can complete the migration by transforming your source server into an image and then using that image to manually create an ECS instance.
- If you have already purchased a destination ECS instance, you can migrate the source server directly to the purchased ECS instance. Ensure that the storage and operating system of the source server are compatible with the purchased ECS instance.
Scenario 3: Scale in the disks of an ECS instance
ECS does not support scaling in system disks or data disks. To scale in disks when you migrate an ECS instance, you can migrate the instance to a custom image or a destination instance that has smaller disks. For more information, see Scale in disks.
Important
- For Linux servers, you can resize disks during migration only if block replication is disabled.
- For Windows servers, you must compress the disks before migration.

Migration limitations

SMC does not support the migration of ECS instances that are created from Alibaba Cloud Marketplace images. To use this feature, you must be added to a whitelist. For more information, contact us.

Migration impact

Before you start the migration, take note of the impacts described in the following table.

Impact	Description
Migrated data directories	During migration, SMC automatically generates a disk partition structure for the destination that is as consistent as possible with the source server's disk partition structure. You can adjust the partition structure of the destination disk, including partition size, order, transfer method, and LVM configurations. By default, all disks on the server are migrated: If a data disk has no mount target, the 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 prevent migration failure, do not stop, start, restart, or release the intermediate instance, or change its billing method during the migration. After the migration is complete, the intermediate instance is automatically released. Note During each 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. 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 Migration principles.
IP address	The IP address changes after migration, which may cause service interruptions. We recommend that you perform the migration during off-peak hours. If your services involve IP address configurations, modify the domain name resolution and ICP filing information yourself after the migration. If a domain name is already mapped to the source server, map the domain name to the new public IP address of the server. For more information, see Add a website resolution. To keep the private IP address unchanged, perform the following operations: Migrate to a ECS Image: After the migration, specify the primary private IPv4 address of the primary network interface card when you purchase an ECS instance from the custom image. Migrate to a ECS Instance: You can modify the private IPv4 address of the destination instance in the advanced configuration step of the migration settings. You can also modify it after the migration. To keep the public IP address unchanged: If the source ECS instance uses a static public IP address: Before migration, convert the public IP address to an Elastic IP Address (EIP) to retain it. After migration, unbind the EIP and then bind it to the migrated ECS instance. For more information, see Convert a static public IP address to an EIP and Elastic IP Address. If the source ECS instance uses an EIP: After migration, unbind the EIP from the source ECS instance and then bind it to the migrated ECS instance. For more information, see Elastic IP Address.
Underlying hardware devices	The underlying hardware devices change after migration. 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 related web applications after server migration

After you migrate a server to Alibaba Cloud ECS, several aspects of your environment change, including network topology, computing and storage resources, application security settings, costs, monitoring, compatibility, network latency and bandwidth, and backup, recovery, and O&M processes. You must also consider the following aspects:

Impact	Description
Network connectivity	After the server migration, the ECS instance will use a new virtual private cloud (VPC). Its network location and other configurations will change with the VPC migration. This ECS instance cannot directly communicate with the original network or other ECS instances in the VPC. To enable cross-account and cross-VPC communication, see VPC interconnection.
Security group	After the server migration, the ECS instance will use new security group rules to control inbound and outbound traffic. Changes in access rules may affect normal business access. If the destination account's security group does not have corresponding security group rules, you can quickly add them by exporting the rules from the security group associated with the original ECS instance 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. Deploy the SSL Certificate to the 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, Server Load Balancer (SLB), and other settings 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 migration.
To migrate a server across international regions, the migration may be slow because of unstable public network conditions. Estimate the migration time and test the transfer speed. We recommend that you connect the source server to an Alibaba Cloud VPC using a VPN Gateway, Express Connect circuit, or Smart Access Gateway to migrate over a 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 using the public network and can improve migration efficiency.
To migrate the source server to an existing Alibaba Cloud ECS instance:
- If the source server runs Linux, the destination instance must also run Linux. If the source server runs Windows, the destination instance must be a Windows server.
- 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 corresponding disks on the source server. If you plan to reduce the disk size during migration, the disk capacity on the destination instance must be greater than or equal to the used disk space 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

Automatically import the migration source from the console

Cross-account

(Migrate an ECS instance from source Account A to destination Account B): Log on to the RAM console using source Account A to create a role. Then, log on to the SMC console using destination Account B.

Warning

In a cross-account migration scenario, make sure to distinguish between source Account A and destination Account B to prevent the migration from proceeding in the wrong direction.
When you import the migration source, use a RAM user of destination Account B.

Prerequisites

An ECS instance must exist in the source account of the ECS instance to be migrated.
The source server must be in the Running state and its Cloud Assistant Agent must be active. For more information, see View the status of Cloud Assistant Agent and handle exceptions.

Preparations

To perform a cross-account migration from the console, you must use a RAM user to import the migration source. Before you start, log on to the destination account and grant the following permissions to the RAM user:
If no RAM user exists under the account, you can create one.
- AliyunSTSAssumeRoleAccess for calling STS.
- AliyunSMCFullAccess for managing SMC.
- AliyunECSReadOnlyAccess for read-only access to ECS.
- AliyunECSAssistantFullAccess for managing Cloud Assistant.
The following steps show how to grant the AliyunSTSAssumeRoleAccess permission.
1. Log on to the RAM console using the destination Alibaba Cloud account.
2. In the navigation pane on the left, choose Users. Then, click the logon name of the target user.
3. Choose Permission Management > Add Permissions.
4. On the Add Permissions page, search for AliyunSTSAssumeRoleAccess, select the policy, and click OK.
You have recorded the IDs of the source and destination Alibaba Cloud accounts.
1. Log on to the Alibaba Cloud Management Console using the source and destination accounts separately.
2. Hover over the user icon in the upper-right corner to view the account ID.

Procedure

Log on to the RAM console using the account that contains the ECS instance to be migrated (source Account A) to create a role and grant permissions to the role.
1. Choose Permission Management > Policies and click Create Policy. On the Script tab, enter the policy script and then 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. Choose Identity Management > Roles and click Create Role. Set Trusted Entity Type to Alibaba Cloud Account and Trusted Alibaba Cloud Account to Other Alibaba Cloud Account. Enter the destination Alibaba Cloud account ID (destination Account B) and ram-role-smc as the role name. Then, click OK.
3. Click the role name ram-role-smc to open the role details page. Click Permission Management > Add Permissions, select Custom Policy, enter the policy name policy-smc, and click OK.
Use the RAM user of the destination account (the RAM user that is authorized by Alibaba Cloud Account B) to open the SMC console - Cross-account/Same-account Migration page.
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 parameters are described in the following table.

Parameter	Description
Migration Source Type	Alibaba Cloud ECS Instance.
Import Method	Select Console Import. Authorize SMC to remotely connect to the source server from the console to automatically import the migration source. The import process automatically calls the Cloud Assistant feature. Do not interrupt or exit the process.
Cross Alibaba Cloud Account	Cross-account.
Alibaba Cloud Account of Source Server	Enter the Alibaba Cloud account to which the server to be migrated belongs (Account A in the example).
Role of Source Server's Account	Enter the role that you created and authorized in Step 1, for example, ram-role-smc.
Region	Select the region where the server to be migrated is located.
Instance	You can search for and select the Alibaba Cloud ECS instances to be migrated in the specified region by 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 Agent to perform the import. The import process takes about 3 to 10 minutes.
On the Cross-account/Same-account Migration page in the SMC console, check the status of the migration source in the Migration Status column.
- A status of Source Online indicates that the import was successful.
  Note
  In a cross-account ECS instance migration scenario, the public IP address of the source instance may not be displayed, the operating system may not be fully shown, and the instance status may not be recognized. This is normal and does not affect the migration task.
- If the status is different, the import failed. Troubleshoot the issue based on the following solutions and then re-import the source.
  - You can troubleshoot the issue based on the error message in the console or by viewing the SMC client log file. The default installation directories for the SMC client are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For information about common issues and solutions, see SMC FAQ and Troubleshooting.

Same-account

Important

The source server (the source ECS instance) must have public network access.
The source server must be in the Running state and have an active Cloud Assistant Agent. For more information, see View the status of Cloud Assistant Agent and handle exceptions.
If you use a RAM user to import the migration source, you must manage the permissions of the RAM user:
- Grant the AliyunECSReadOnlyAccess permission for read-only access to ECS.
- Grant the AliyunECSAssistantFullAccess permission for managing Cloud Assistant.

Open the SMC console - Cross-account/Same-account Migration page.
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 parameters are described in the following table.

Parameter	Description
Migration Source Type	Alibaba Cloud ECS Instance.
Import Method	Select Console Import. Authorize SMC to remotely connect to the source server from the console to automatically import the migration source. The import process automatically calls the Cloud Assistant feature. Do not interrupt or exit the process.
Cross Alibaba Cloud Account	Same-account.
Region	Select the region where the server to be migrated is located.
Instance	You can search for and select the Alibaba Cloud ECS instances to be migrated in the specified region by instance ID/name or IP address. You can select multiple instances for batch import.

Configure the parameters and click Import.
SMC automatically starts the Cloud Assistant Agent to perform the import. The import process takes about 3 to 10 minutes.
On the Cross-account/Same-account Migration page in the SMC console, check the status of the migration source in the Migration Status column.
- A status of Source Online indicates that the import was successful.
  Note
  In a cross-account ECS instance migration scenario, the public IP address of the source instance may not be displayed, the operating system may not be fully shown, and the instance status may not be recognized. This is normal and does not affect the migration task.
- If the status is different, the import failed. Troubleshoot the issue based on the following solutions and then re-import the source.
  - You can troubleshoot the issue based on the error message in the console or by viewing the SMC client log file. The default installation directories for the SMC client are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For information about common issues and solutions, see SMC FAQ and Troubleshooting.

Import the migration source using the command line (Recommended)

Important

The source server must have public network access. If the source server has firewall restrictions, see What are the SMC service domain names? to obtain the SMC domain names and ports, and add them to the firewall whitelist.
If your source server cannot access the public network or you want to improve migration efficiency using a private network, see the private network migration solution.

Obtain the activation code command.

Based on the migration scenario, select the corresponding Alibaba Cloud account and open the SMC console - Cross-account/Same-account Migration page.
- Same-account migration: Log on to the SMC console using the Alibaba Cloud account to which the source ECS instance belongs.
- Cross-account migration (Migrate an ECS instance from source Account A to destination Account B): Log on to the SMC console using destination Alibaba Cloud Account B.
  Warning
  - In a cross-account migration scenario, make sure to distinguish between source Account A and destination Account B to prevent the migration from proceeding in the wrong direction.
  - When you import the migration source, you must enter the activation code or AccessKey pair of destination 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 parameters are described in the following table.

Parameter	Description
Migration Source Type	Alibaba Cloud ECS Instance.
Import Method	Select Command Line Import.
Activation Quota	The number of migration sources that can be activated by the activation code. The value ranges from 1 to 1000. The default value is 200.
Validity Period	The validity period of the activation code. The value ranges from 1 to 90 days. The default value is 90 days.
Activation Code	After generating the activation code, copy the command. Perform the following 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.
  After you run the command, a message similar to Import Source Server [s-bp18x8751kgz2oyh****] Successfully! appears, which indicates that the migration source was imported successfully.
Windows source server
1. Log on to the Windows source server.
2. Open Windows PowerShell with administrator privileges.
3. Paste and run the copied command to import the migration source.
  After you run the command, a message similar to Import Source Server [s-bp19rlidl3mwuptc****] Successfully! appears, which indicates that the migration source was imported successfully.
  If the command fails to run, see What do I do if the command fails to run when I import a Windows migration source from the command line?.
On the Cross-account/Same-account Migration page of the SMC console, you can check the status of the migration source in the Migration Status column.
- A status of Source Online indicates that the import was successful.
  Note
  In a cross-account ECS instance migration scenario, the public IP address of the source instance may not be displayed, the operating system may not be fully shown, and the instance status may not be recognized. This is normal and does not affect the migration task.
- If the status is different, the import failed. Troubleshoot the issue based on the following solutions and then re-import the source.
  - You can troubleshoot the issue based on the error message in the console or by viewing the SMC client log file. The default installation directories for the SMC client are:
    - Windows server: C:\smc.
    - Linux server: /smc.
  - For information about common issues and solutions, see SMC FAQ and Troubleshooting.

Import the migration source using the SMC client

For more information about the SMC client, see SMC client guide.

Important

You must run the client on the source server. By default, public network access is enabled. If the source server has firewall restrictions, see What are the SMC service domain names? to obtain the SMC domain names and ports, and add them to the firewall whitelist.
If your source server cannot access the public network or you want to improve migration efficiency using a private network, see the private network migration solution.

Based on the migration scenario, select the corresponding Alibaba Cloud account and open the SMC console - Cross-account/Same-account Migration page.
- Same-account migration: Log on to the SMC console using the Alibaba Cloud account to which the source ECS instance belongs.
- Cross-account migration (Migrate an ECS instance from source Account A to destination Account B): Log on to the SMC console using destination Alibaba Cloud Account B.
  Warning
  - In a cross-account migration scenario, make sure to distinguish between source Account A and destination Account B to prevent the migration from proceeding in the wrong direction.
  - When you import the migration source, you must enter the activation code or AccessKey pair of destination Account B.
On the Cross-account/Same-account Migration page, click Import Migration Source.

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

Parameter	Description
Migration Source Type	Alibaba Cloud ECS Instance.
Import Method	Client Import.
Import Instructions	In the Import Instructions section, based on the source server's operating system (Linux or Windows) and architecture (32-bit or 64-bit), download, install, and activate the corresponding SMC client as prompted. Click Generate Activation Code and copy the activation code information. You need to 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 loses connection with the SMC console, which causes the migration to fail.
Windows source server
1. Use a remote connection tool that supports file transfer, such as WinSCP, to upload the downloaded SMC client to the Windows source server.
2. On the Windows source server, use the system's built-in decompression tool or a self-installed decompression tool to extract the SMC client package.
3. In the SMC client folder that matches your source system version, double-click the go2aliyun_client.exe application.
  When prompted for administrator permissions, click OK.
4. Obtain an activation code or an AccessKey pair.
  - (Recommended) To obtain an activation code, in the Import Instructions section of the SMC console, click Generate Activation Code and copy the activation code.
  - 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, you can create an AccessKey pair.
5. As prompted, enter the values for 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, the migration source is imported.
Linux source server
1. Use a remote connection tool that supports file transfer, such as WinSCP, to upload the downloaded SMC client to the Linux source server.
2. Remotely connect to the Linux source server and decompress the SMC client package.
  This example uses the Linux 64-bit General-purpose Edition. If you use a different version of the SMC client, replace the package name in the command with the actual downloaded file name.
```
tar -zxvf go2aliyun_client.tar.gz
```
  Note
  The Linux 64-bit Arm Edition supports the g6r general-purpose instance family and the c6r compute-optimized instance family. For more information, see Arm-based enterprise-level computing instance families.
3. (Optional) You can filter and exclude files or directories that do not need to be migrated as needed.
4. Obtain an activation code or an AccessKey pair.
  - (Recommended) Obtain an activation code: In the SMC console, go to the Import Instructions section, click Generate Activation Code, and then copy the activation code.
  - 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, you can create an AccessKey pair.
5. In the SMC client folder, run the following commands to run 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 activation code or AccessKey pair, the following prompts may appear:
  - If the snapshot driver is not installed on the source system, the SMC client displays the following prompt.
    Because scaling in a Linux server requires disabling block replication, enter no.
    Important
    If the snapshot driver fails to install, do not enable block replication when you create the migration task. Otherwise, the migration fails.
  - Most mainstream source systems have rsync installed by default. If not, the SMC client prompts you. Enter yes to automatically install rsync.
  - If SELinux is enabled on the 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, the migration source is imported.
  Note
  If importing the migration source fails, you can troubleshoot the issue based on the returned message. Then, run the following commands to exit the background program and re-import the migration source. For 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 in the SMC console, check the status of the migration source in the Migration Status column.
- If the status is Source Online, the import succeeded.
- If the status is different, the import failed. Troubleshoot the issue based on the following solutions and then re-import the source.
  - You can troubleshoot the issue based on the error message in the console or by viewing the SMC client log file. The default installation directories for the SMC client are:
    - Windows source server: C:\smc.
    - Linux source server: /smc.
  - For information about common issues and solutions, see SMC FAQ and Troubleshooting.

Step 2: Configure the migration

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 a target type based on your migration scenario: ECS Image Convert the existing source server into a custom cloud server image, and then use this custom image to create a new ECS instance to complete the migration. The configuration items are described as follows: Destination Region: The region where your source server will be migrated to in Alibaba Cloud. 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 an existing ECS instance. The storage, operating system, and other configurations of the source server and the existing ECS instance must be compatible. Important When migrating to a destination instance, the operating system of the destination instance is replaced first. The 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 cancel the automatic release of snapshots with the disk before migration. For more information, see Configure automatic snapshots to be released with disks. The configuration items are described as follows: Destination Region: The region where your source server will be migrated to in Alibaba Cloud. This parameter is required. For more information about regions, see Regions and zones. Destination Instance: Select an ECS instance as the destination instance.
Migration Test	The migration drill feature helps you fully understand the feasibility and risks of the migration task before the actual migration. It also provides information such as the amount of data to be migrated, 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 Test is enabled. Warning If the target 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 method is Test Only, the snapshots will be automatically rolled back after the migration drill is completed. The destination ECS instance will be unavailable during the migration drill, and data will be lost during this period. Ensure that the destination ECS instance does not contain important data. For more information, see Configure a migration drill.
Execution Method	Select an execution method based on whether Migration Test is enabled: If Migration Test is enabled Test Only: Creates only a migration drill task. After the migration drill is completed, to migrate the server, you must manually start the server migration task. Test and Migrate: After the migration drill is completed, if there are no drill items with a status of Critical, the system automatically starts the server migration task. By default, Test and Migrate is selected. If Migration Test is not enabled Migrate Now: Starts the migration immediately after creating the migration task. By default, Migrate Now is selected. Migrate Later: After creating the migration task, it automatically starts at the set time. Note The earliest scheduled execution time can be set to 10 minutes after the current time. Create Only: Creates only the migration task. You will need to manually start the migration task later by clicking Start Migration Job in the Actions column.
Automatic Incremental Synchronization	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: Synchronization Interval: The time interval at which the incremental migration task is automatically executed periodically. Maximum Reserved Images: The maximum number of images that the incremental migration task retains by default. The migration task will be executed periodically to synchronize incremental data to Alibaba Cloud. For best practices on incremental migration, see Incremental server migration. If you disable this switch, the migration task will run only once.
Enable a migration template	This parameter appears only when Destination Type is set to ECS Image. A migration template is used to preset the parameters of a migration task. When you start the migration, the template parameters are automatically filled in. For more information about setting a migration template, see Set a migration template.
Network Type	Select the network used to transfer migration data to the intermediate instance. By default, public network transfer is used. The intermediate instance will be created in the selected virtual private cloud (VPC) and vSwitch, so the intermediate instance will be assigned a public IP address. Public Network (Default) Migration data is transferred to the intermediate instance over the public network. To use this mode, the source server must be able to access the public network. Choose whether to specify a VPC and vSwitch as needed. Specify VPC and vSwitch: The migration task creates an intermediate instance in the VPC and vSwitch you specify. Do not specify VPC and vSwitch: The migration task creates an intermediate instance in a new VPC and vSwitch that the system automatically creates. VPC Migration data is transferred to the intermediate instance over the VPC intranet. To use this mode, you need to connect the source server to the Alibaba Cloud VPC and must specify a VPC and vSwitch. Note If you can directly access a VPC in an Alibaba Cloud region from your on-premises data center (IDC), VM environment, or cloud host, we recommend that you use this method for migration. Using intranet transfer provides faster and more stable data transfer than the public network, improving migration efficiency. You can connect the source server and the cloud VPC through a VPN Gateway, Express Connect circuit, or Smart Access Gateway. For more information, see Connect VPC to data center, office terminal, and other cloud.
The private IPv4 address of the destination instance	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. Remain unchanged: By default, the migration IP address of the Destination Instance remains unchanged. Manual: Allows you to enter an address within the available IP range of the Destination Instance's vSwitch. When the migration source IP address is in the vSwitch's network segment, you can change the destination instance IP address to the migration source IP address. When the destination instance network segment is the same as the migration source network segment: Directly enter the private IP address of the migration source. When the destination instance network segment is different from the migration source network segment: You first need to change the VPC of the destination instance so that the destination instance network segment is the same as the migration source network segment, and then enter the private IP address of the migration source.

Adjust the disk partition structure as needed. The parameters are described in the following table.

Parameter

Description

Modify Disk Partition

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 disk information of the source instance is not displayed. The system automatically reads the source instance disk information and generates a disk structure. After migration, the destination disk partition structure is consistent with the automatically generated disk structure by default.
Enabled: The disk information of the source instance is displayed. The system automatically reads the source instance 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 parameters for the disk partition structure are described as follows:
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 2048.
The destination system disk size must be larger than the actual used size of the source system disk. For example, if the source system disk is 400 GiB and the actual used space is 100 GiB, 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 data disk of the Alibaba Cloud server after migration, in GiB. The data disk size ranges from 1 to 32768.
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 size of the source data disk. For example, if the source data disk is 500 GiB and the actual used space is 100 GiB, the destination data disk size must be greater than 100 GiB.
If there is no mount target under the Data Disk or all mount targets are set not to be migrated, the data disk will not be migrated.
LVM: Logical Volume Manager (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 end will automatically rebuild the disk with an LVM structure.
An example is described as follows:
For each destination disk with LVM enabled, the system creates 1 physical volume (PV) and its corresponding volume group (VG). On this volume group, it creates a number of logical volumes (LVMs) corresponding to the number of mount targets. The volume group name defaults to vgX (where X is the disk's sequence number), and the logical volume name defaults to lvX (where X is the logical volume's sequence number), as shown in the following example:
Important
LVM is not supported in the following cases:
If the migration source is a Windows system, LVM is not supported.
If the system disk has no boot partition, LVM is not supported.
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 a disk with an XFS file system is 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 migration source disk partitions.
If the migration source does not support enabling Block Replication for a partition, the switch cannot be turned on. The default file replication is used, and the partition size can be modified.
If the migration source supports enabling Block Replication for a partition, 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 a 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 the partition sizes cannot exceed the size of the belonging disk.
Note
If the disk sizes of the destination instance do not match the migration source disks, the task cannot be created. In this case, the system will automatically adjust the mount target positions to meet the disk size requirements. If the requirements are still not met after adjusting the mount targets, handle the issue according to the prompts on the page.
You can also manually drag the mount target positions to meet the disk size requirements. However, dragging is not supported for boot or system partitions. Perform the following steps:
Hover your mouse over the icon in front of the mount target.
Use the mouse to drag the mount target to another disk.

(Optional) Click Advanced Settings to configure parameters such as the network mode, private IP address, and transfer throttling. For more information about these parameters, see the following table.

Note

We recommend setting Network Mode to Private Network. A private network provides faster and more stable data transfer than a public network, which improves migration efficiency.

Parameter	Description
Migration Job Name	The name of the migration task.
Job Description	Enter a description for the migration task.
Transmission Speed Limit	Transfer throttling limits 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 transfer speed of compressed data) 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 consumption of CPU resources on the migration source. The value ranges from 0 to 10. The default value is 7. A value of 0 means no data compression.
Checksum Verification	Disabled by default. Enabling it enhances data consistency checks but may reduce transfer speed.
SSL-Encrypted Transmission	By default, Auto is selected. Using Secure Sockets Layer (SSL) encryption to transfer migration data can improve data security and ensure data integrity.
License Type	Select the license type. Alibaba Cloud (Default): Currently only supports providing Microsoft Windows Server licenses. After migration, when creating an ECS instance from an image in Hong Kong (China) and overseas regions, a license fee for the image will be charged, and it will be automatically activated. The specific fee is subject to the information displayed when creating the instance. BYOL: Bring Your Own License (BYOL) migration to the cloud currently mainly includes Microsoft, Red Hat Enterprise Linux, and SUSE Linux Enterprise Server. After migration, no image license fee will be charged when creating an ECS instance from the image. 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 a specified ECS instance. For more information, see Purchase a software license for an ECS instance.
Image Check	The image detection feature mainly checks whether the 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 can help you quickly identify potential problems with the image or instance after migration and provide repair solutions to make it comply with Alibaba Cloud standards, improving the success rate of instance startup. For more information, see Configure image detection.
Tag	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 maximum of 20 tags can be bound to a single migration task.
Intermediate Instance Type	You can select the intermediate instance type based on your actual needs. This parameter appears only when Destination Type is set to ECS Image. After you specify this parameter, the system selects this instance type to create the intermediate instance. If this instance type is out of stock, the migration task fails to be created. Do not select an intermediate instance type: The system selects instance types in a default order 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.
Report diagnostic logs	Automatically upload SMC client logs to the SMC server for error diagnosis and analysis, which helps in locating 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 path.

In the message that appears, read the migration notes and click Got It.
On the Cross-account/Same-account Migration page, you can view the migration status.
If you enabled a migration drill, SMC first performs the migration drill. The transfer time is affected by factors such as data volume and network bandwidth. Wait for the migration task to complete.
Note
- Speed: The transfer speed of uncompressed migration data, measured per second. If the Compression Ratio is set to a value greater than 0 when you create a migration task, the displayed speed is higher than the actual network transfer speed of the compressed data.
- Remaining Sync Time: Calculated as (Total Data Volume - Transferred Data Volume) / Speed.
- If the transfer speed is too slow to meet your plan, 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.
To subscribe to migration error events, modify the migration, or pause the migration, perform the following operations:
- To prevent the migration process from being interrupted by task errors, you can subscribe to SMC migration task error event notifications in Cloud Monitor to receive timely email notifications.
- While a migration task is in the Syncing state, you can perform the following operations on the task as needed:
  To modify a migration task, click Modify Migration in the Actions column. You can then change parameters such as the transmission speed limit, compression ratio, and Checksum verification.
  To pause a migration task, click Pause Migration in the Actions column.
(Optional) View migration details.
In the Migration Source ID/Name column, click a migration source ID to view its details.

Verify the migration

The migration is complete when the Migration Status is Completed.
- If you set Destination Type to ECS Image:
  After a successful migration, an Alibaba Cloud custom image is created. To view the image detection results, scroll to the right and click View Report in the Migration Deliverables column. For more information, see View image detection results.
  Manually verify the migration result (Recommended)
  In the Actions column, click Create Instance. You are redirected to the instance creation page in the ECS console, where the custom image is preselected. For more information, see Create an instance from a custom image or shared image.
  Automatically verify the migration result
  Note
  To use this feature, the Cloud Assistant Agent must be installed on the instance, and the instance's system version must support it. For more information, see Install the Cloud Assistant Agent.
  This feature uses the OOS template ACS-SMC-CreateAndVerifyInstance provided by Alibaba Cloud to automatically verify that the image generated by the migration task can be used to successfully create and start an ECS instance.
  In the Actions column, click View Migration Result.
  In the dialog box that appears, review the verification process and click Verify Now.
  You can also click Customize Verification Parameters to manually configure verification parameters.
  You can view the result in the Verify Migration Result column.
  Verified: The migration passed verification. You can click View Report to view the results.
  Not Verified: Indicates that the migration was abnormal. You can click View Cause to view the error details and troubleshoot the issue.
  To view the execution history of the OOS template, you can also click the icon in the Actions column and then click View Verification Records in OOS Console.
- If you set Destination Type to ECS Instance for the migration, you can click View Destination Instance in the Actions column to view the destination ECS instance.
After you migrate the server, perform the following operations to ensure that your business runs normally:
- Verify the data to ensure its integrity and correctness. For more information, see How do I check my system after I migrate a Linux server? or How do I check my system after I migrate a Windows server?.
- If applications and services on the source server are not configured to start automatically, you must manually start them after the migration.
- The IP address changes after 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 already mapped to the source server, map the domain name to the new public IP address of the server. For more information, see Add a website resolution.
  To keep the private IP address unchanged, you can modify the private IP address after the migration is complete.
  ECS Image: When you create an ECS instance, you can specify a private IP address. For more information, see Specify the primary private IPv4 address of the primary network interface card when purchasing an ECS instance.
  When migrating to a ECS Instance, if you do not modify the private IPv4 address in the advanced configuration during the migration settings step, you can do so after the migration is complete. For more information, see Modify the primary private IPv4 address of the primary network interface card of 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 about Server Migration Center (SMC) 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 release an intermediate instance by accident? section of the "FAQ" topic.
If the Real-time Migration Status is Error, the migration task has encountered an error.
In this case, you need to troubleshoot the problem and retry the migration:
1. In the Actions column, click Troubleshoot Errors. Use the error code and error message to resolve the issue. For more information, see SMC FAQ and Troubleshooting.
2. After you resolve the issue, click Retry Migration Job in the Actions column. The migration will resume.
  Important
  If the intermediate instance has been released, you must start the migration again. For more information, see What do I do if I accidentally release the intermediate instance?.

Clean up resources

Migrate to a cloud server image

During migration, SMC creates a temporary pay-as-you-go intermediate instance named No_Delete_SMC_Transition_Instance in your destination Alibaba Cloud account to facilitate the migration. You must decide whether to manually release the instance based on the migration outcome:

Successful migration: The intermediate instance is automatically released. You do not need to manually release it.
Migration error: The intermediate instance is retained for the migration task and incurs charges. You can release it in the following ways to avoid unnecessary charges:
- To delete a migration task and automatically clean up the intermediate instance, click the migration source ID, and then click Cancel Migration Job in the Actions column for the task.
- Manually release the intermediate instance.

Migrate to a destination instance

During migration, SMC creates a temporary pay-as-you-go intermediate disk named SMC_Temp_Disk and attaches it to the destination instance to facilitate the migration. You must decide whether to manually release this intermediate disk based on the migration outcome:

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

Server Migration Center:Migrate ECS instances between accounts or within the same account

Migration scenarios

Migration limitations

Migration impact

Preparations

Migration procedure

Step 1: Import the migration source

Automatically import the migration source from the console

Cross-account

Prerequisites

Preparations

Procedure

Same-account

Import the migration source using the command line (Recommended)

Linux source server

Windows source server

Import the migration source using the SMC client

Windows source server

Linux source server

Step 2: Configure the migration

ECS Image

ECS Instance

If Migration Test is enabled

If Migration Test is not enabled

Public Network (Default)

VPC

Configure disks

Configure mount targets

Verify the migration

Manually verify the migration result (Recommended)

Automatically verify the migration result

Clean up resources

Migrate to a cloud server image

Migrate to a destination instance

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