How to perform agentless migration for VMware VMs - Server Migration Center

Agentless migration for VMware virtual machines (VMs) is a non-intrusive method that does not consume compute resources from the guest operating system. This method helps address concerns about server security and performance. This topic describes how to use Server Migration Center (SMC) to migrate VMware VMs without an agent.

Note

You can also migrate VMware VMs with an agent. For more information, see Migrate servers to Elastic Compute Service.

Migration scenarios

Important

Due to a change in the intermediate technology solution for server migration, Server Migration Center (SMC) will no longer support migrating Windows servers to destination instances in Alibaba Cloud regions outside the Chinese mainland after 11:59 PM (UTC+8) on November 30, 2025. Before this date, SMC client V2.8.5 and earlier can still be used. For more information about the change and its impact, see Notice on SMC Discontinuing Support for Migrating Windows Servers to Destination Instances in Regions Outside the Chinese mainland.

(Recommended) Migrate a server to an Alibaba Cloud ECS custom image.
If you have not purchased an Alibaba Cloud ECS instance, you can migrate your server to an Alibaba Cloud ECS custom image. Then, you can use the custom image to manually create an ECS instance.
Migrate a server to an existing Alibaba Cloud ECS instance.
If you have already purchased an Alibaba Cloud ECS instance and its storage, operating system, and other configurations are compatible with the source server, you can migrate the source server to the existing ECS instance.
Warning
After migration, the original data on the destination ECS instance is erased. The data on the source server is not affected. Therefore, do not use this method if the destination ECS instance contains important data.

Limits

Environment requirements

Different OVA templates have different environment requirements, as shown in the following table.

OVA template

VMware agentless connector configuration

vCenter deployment

Standalone ESXi deployment

SMC VMware Connector 6.7 OVA

vCPU: 4 vCPUs or more
Memory: 8 GB or more
Disk: 40 GB or more

vCenter version: 6.0, 6.5, or 6.7
ESXi version of the host where the connector resides: 6.0, 6.5, or 6.7
ESXi version of the host where the VM to be migrated resides: 6.0, 6.5, or 6.7
Hardware version of the VM to be migrated: 11, 12, 13, 14, or 15

ESXi version: 6.0, 6.5, or 6.7
Hardware version of the VM to be migrated: 11, 12, 13, 14, or 15

SMC VMware Connector 8.0 OVA

vCPU: 4 vCPUs or more
Memory: 8 GB or more
Disk: 40 GB or more

vCenter version: 6.7, 7.0, or 8.0
ESXi version of the host where the connector resides: 6.7, 7.0, or 8.0
ESXi version of the host where the VM to be migrated resides: 6.7, 7.0, or 8.0

Hardware version of the VM to be migrated: 14, 15, 16, 17, 18, 19, 20, or 21

ESXi version: 6.7, 7.0, or 8.0
Hardware version of the VM to be migrated: 14, 15, 16, 17, 18, 19, 20, or 21

Supported operating systems

The SMC client automatically detects the operating system of the VM to be migrated. The following operating systems are supported. You can run the cat /proc/version command or the systeminfo command to view the operating system.

CentOS
Ubuntu
SUSE
OpenSUSE
Debian
RedHat
Others Linux
Windows Server 2003
Windows Server 2008
Windows Server 2012
Windows Server 2016
Windows Server 2019
Windows Server 2022

Disk size limits

SMC has limits on the size of source disks that can be migrated. If a single disk exceeds the maximum supported capacity, SMC cannot migrate it. If the capacity exceeds the limit, you must transfer the data using a data migration method, such as cp or sftp.

System disk: The maximum capacity is 2 TiB.
Data disk: The maximum capacity is 32 TiB.

Role permission requirements

If you use a vCenter user, the role assigned to the user for the ESXi host and VM must have the following permissions:
- Datastore > Browse datastore
- Datastore > Low-level file operations
- Host > Local operations > Create virtual machine
- Virtual machine > Change Configuration > Acquire disk lease
- Virtual machine > Change Configuration > Toggle disk change tracking
- Virtual machine > Provisioning > Allow virtual machine download
- Virtual machine > Provisioning > Allow disk access
- Virtual machine > Provisioning > Allow read-only disk access
- Virtual machine > Snapshot management > Create snapshot
- Virtual machine > Snapshot management > Remove Snapshot

If you use an ESXi user, the role must be Administrator.

Migration fees

SMC is a free service. However, you are charged for the Alibaba Cloud ECS resources that are used during the migration, such as intermediate instances and intermediate disks. For more information about billing, see SMC billing items.

Prerequisites

Complete the pre-migration preparations. For more information, see Pre-migration preparations.
To prevent data loss, back up important data to an image, a snapshot, or a storage device external to the instance.
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.

Procedure

Step 1: Create a VMware agentless connector

SMC provides an OVA template file. Import the VMware agentless connector OVA template into your vCenter or ESXi environment to deploy the VMware agentless connector.

Note

An Open Virtualization Format (OVF) file is an open standard that describes a portable, secure, efficient, and extensible format for packaging and distributing software. An OVF package consists of several files, such as an .ovf file, an .mf file, a .cert file, .vmdk files, and .iso files. An Open Virtualization Appliance (OVA) is a single-file distribution of an OVF package.
VMware vSphere is VMware's virtualization stack that transforms data centers into aggregated computing infrastructures that include CPU, storage, and networking resources. vSphere manages these infrastructures as a unified operating environment and provides you with tools to manage the data centers that join the environment. The two core components of vSphere are ESXi and vCenter Server. ESXi is the virtualization stack used to create and run VMs and virtual appliances. vCenter Server is a service used to manage multiple hosts connected in a network and to pool host resources.

Download and decompress the OVA template

Click Download OVA template. In the Import Instructions section, download and decompress the OVA template file matching your VMware ESXi or vCenter version.

lQLPJxjJZIQrsxPMl80C7rBONH3msCozYwaTnoZxcjUA_750_151

Deploy the VMware agentless connector

Import the VMware agentless connector OVA template file into your vCenter or ESXi environment to deploy the VMware agentless connector. You can deploy the connector in vCenter or in a standalone ESXi environment based on your needs.

Deploy in vCenter (Recommended)

Import the VMware agentless connector OVA template into your vCenter environment to deploy the VMware agentless connector. The following steps use vCenter 6.7 as an example:

Log on to vCenter. On the vCenter host, right-click Deploy OVF Template....
On the Deploy OVF Template page, follow the wizard to create a virtual machine (VM).
1. Select the OVA template and click NEXT.
  Select Local file and click Browse... to select the decompressed OVA template file.
2. Specify a name and location for the VM and click NEXT.
  You can enter a name in the Virtual machine name field and select a location.
3. Select a compute resource and click NEXT.
4. Verify the template details and click NEXT.
5. Select a storage space and click NEXT.
6. Select a network resource and click NEXT.
7. Review the configuration details and click FINISH.
8. Once the deployment is complete, right-click the VMware agentless connector and choose Power > Power On.
9. Configure the network environment to ensure that the created VMware agentless connector can connect to port 443 (default) of vCenter and port 902 (default) of the ESXi host where the VM to be migrated resides.
10. On the Summary tab, you can obtain the IP address of the VMware agentless connector.

Deploy in a standalone ESXi environment

Import the VMware agentless connector OVA template into your ESXi environment to deploy the VMware agentless connector. The following steps use ESXi 7.0 as an example:

Log in to VMware ESXi. Right-click Virtual Machines and click Create/Register VM.
On the Select Creation Type page, select Deploy a virtual machine from an OVF or OVA file and click Next.
On the Select OVF And VMDK Files page, enter a name for the VM, click Click To Select Files Or Drag/drop to select the downloaded OVA template file, and then click Next.
On the Select Storage page, click Next.
On the Deployment Options page, click Next.
On the Ready To Complete page, click Finish.
Wait for the VM to be deployed. The IP address of the connector is displayed in the General Information section. By default, the connector network is configured using DHCP. You can change the network configuration as needed.
Configure the network environment to ensure that the created VMware agentless connector can connect to ports 443 and 902 (default) of the ESXi host.

Step 2: Import the migration source

Log on to the VMware agentless connector, add and configure the VMs to be migrated, and then run the import command in the connector to import the VMs to the SMC console.

Add VMs to be migrated (multiple VMs are supported)

Use the configure.sh script to add the VMs to be migrated. You can add multiple VMs at a time. The corresponding number of migration sources will then appear in the SMC console.

Note

A single VMware agentless connector can import and associate with a maximum of 10 migration sources at a time. If you configure more than 10 VMs to be migrated, only 10 migration sources appear in the SMC console. The remaining migration sources are automatically imported after the current migration tasks are complete.
The operating system type preset when creating a VM in VMware vCenter may not be accurate. Confirm the operating system type.

Log on to the VMware agentless connector.
The following steps use an SSH remote connection as an example:
In a terminal that can connect to the VMware agentless connector, run the following command to remotely connect to the connector. The default username is root, and the password is empty by default.
```
ssh root@<IP address of the VMware agentless connector>
```
Important
For security reasons, change the password promptly.
Run the following command to check whether the time is correct.
```
date
```
If the time is incorrect, use the ntpdate command to calibrate it. This example uses the 0.asia.pool.ntp.org time server.
```
ntpdate 0.asia.pool.ntp.org
hwclock --systohc
```
Warning
If the time is incorrect, importing the migration source will fail.

Run the following command to configure vCenter or ESXi and the VMs to be migrated.

Note

This step retrieves a list of all hosts and VMs in the environment. If you already know the name of the host or VM you need to configure, you can skip this step and specify the name directly. For more information, see How do I directly specify a VM or a VM under a host for agentless migration of VMware VMs?.

cd /root/smc
bash configure.sh

Enter the IP address, username, password, and port number (default is 443) of VMware vCenter or ESXi in sequence. The output is similar to the following.

[root@localhost ~]# cd /root/smc
[root@localhost smc]# ./configure.sh
Please input vCenter/ESXi IP:192.168.XX.XX
Please input username:administr****@vsphere.local
Please input password:
Please input port number(default 443):443

A message indicates that the connection is successful, a list of hosts is generated, and you are prompted to enter the host corresponding to the VM to be migrated. Select a host that is connected, indicated by an asterisk (*) in the Connected column.

Test to connect the vCenter/ESXi...
Connect success!
save to ./vmware_connect_config.json
========Aliyun SMC VMware Configure Tool 1.2========
Connect success!
 Getting host list progress:
 [>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>100.00%]time: 1.0s


Host List:
------------------------------------------------------------------------
ID      Name                              Version            Connected
1       192.168.XX.XX                     6.7.0                  *
2       192.168.XX.XX                     7.0.3                  *
------------------------------------------------------------------------
Please input the ID of Host(input 0 to exit):1

After entering the host ID, a list of VMs is generated, and you are prompted to enter the ID of the VM to be migrated. Select a VM that is connected, indicated by an asterisk (*) in the Connected column.

Test to connect 192.168.XX.XX
Connect success!
 Getting vm list progress:
 [>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>100.00%]time: 2.3s


VM List of 192.168.XX.XX:
------------------------------------------------------------------------
ID      Name                               Connected      CBT      Add
1080    test1                                  *
1084    win16bios                              *
1011    centos7-bios-2                         *
3008    centos7-uefi                           *
2001    centos-hw10                            *
------------------------------------------------------------------------
Please input the ID of VM to be migrated (input 0 to exit):1084

Select the architecture of the VM to be migrated.

--------------------------------------------------------------
0    x86_64
1    i386
2    arm64
--------------------------------------------------------------
Please choose the architecture:0

If the operating system of the current VM is not successfully identified, enter the number corresponding to the operating system from the provided list. For example, enter 10.

------------------------------------------------------------------------
0	CentOS
1	Ubuntu
2	SUSE
3	OpenSUSE
4	Debian
5	RedHat
6	Others Linux
7	Windows Server 2003
8	Windows Server 2008
9	Windows Server 2012
10	Windows Server 2016
11	Windows Server 2019
12	Windows Server 2022
------------------------------------------------------------------------
Current OS [Apple macOS 10.14 (64-bit)] is invalid, please choose the OS of VM:10

An asterisk (*) in the Add column next to the VM name indicates that the VM was added successfully.

VM List of 192.168.XX.XX:
--------------------------------------------------------------
ID      Name                     Connected      CBT      Add  
481     TEST_CLONE_1                 *      
389     win16bios                    *                    *  
338     hanjun_test_001              *  
386     Aliyun_SMC_Agent_6.5         *  
393     win16uefi   
--------------------------------------------------------------
Please input the ID of VM to be migrated (input 0 to exit):0

Note

To migrate multiple VMs, continue entering the IDs of the VMs to be migrated.
If you are migrating only one VM, enter 0 to return to the host selection. To select VMs from other hosts, repeat the preceding steps. Otherwise, enter 0 to exit the configuration.

(Optional) Configure the VMs to be migrated

Use the vmware_migrate_config.json file to confirm and modify properties of the VMs to be migrated, such as the operating system, disks, and whether to migrate them.

Run the following command to view the generated vmware_connect_config.json and vmware_migrate_config.json files.

ll

The output is similar to the following.

[root@localhost smc]# ll
total 5588
drwxrwxrwx. 4 root root     239 Oct 17 17:27 Check
-rwxrwxrwx. 1 root root    6884 Oct 14 15:54 client_data
-rwxrwxrwx. 1 root root     151 Oct 14 17:47 configure.sh
drwxrwxrwx. 2 root root      72 Nov  1 01:15 dist
-rwxrwxrwx. 1 root root   38878 Oct 14 15:54 EULA
drwxrwxrwx. 2 root root    4096 Oct 17 17:27 Excludes
-rwxrwxrwx. 1 root root 5633792 Oct 31 19:43 go2aliyun_client
-rwxrwxrwx. 1 root root     146 Oct 14 15:54 user_config.json
-rw-r--r--. 1 root root     263 Nov 10 18:05 vmware_connect_config.json
-rw-r--r--. 1 root root   18406 Nov 10 18:07 vmware_migrate_config.json

Check whether the properties of the VM, such as the operating system, disks, and migration status, meet your expectations.

vim vmware_migrate_config.json

The vmware_migrate_config.json file is in JSON format. Each VM corresponds to a key-value pair in the array. The key is the Moref ID of the VM, which is a unique identifier for different objects or resources in a VMware vSphere environment. The value contains the property information of the VM. The key-value pair for each VM is as follows:

 "1": {
        "vm_name": "centos7-bios-main",
        "moref_id": "1",
        "uuid": "1:525794aa-d3e9-2332-5d78-78a6e6d6d4f3:564dfd2b-91ab-1cae-2bef-cda625472b28",
        "cores": 2,
        "memory": 4.0,
        "boot_mode": "bios",
        "vdisk_num": 3,
        "host": "localhost.localdomain",
        "cpu_info": "Intel(R) Xeon(R) Platinum 8269CY CPU @ 2.50GHz",
        "virt_type": "VMware7,1",
        "host_id": "ddbd4d56-f407-f342-a8fa-2edd5424b34e",
        "CBT_enabled": true,
        "power_state": false,
        "connect_state": true,
        "mac": "unavailable",
        "tools_state": false,
        "ipv4": null,
        "guestOS": "CentOS 7 (64-bit)",
        "host_name": null,
        "disk": [
            {
                "key": 2000,
                "uuid": "6000C296-2b4b-5c40-2d8b-dfbc757641a2",
                "capacity": 20971520,
                "file_name": "[datastore1] centos7-bios/centos7-bios-000009.vmdk",
                "change_id": "52 fc 41 38 48 e7 cc cc-cd af c1 f8 44 f3 0d e9/21",
                "system_disk": true,
                "migrate": true
            },
            {
                "key": 2002,
                "uuid": "6000C294-4055-f564-1190-e365396eb0a6",
                "capacity": 22020096,
                "file_name": "[datastore1] centos7-bios/centos7-bios_2-000009.vmdk",
                "change_id": "52 74 c8 ba 23 f6 cd 8b-2c c5 94 40 cd b1 f5 e9/21",
                "system_disk": false,
                "migrate": true
            },
            {
                "key": 2003,
                "uuid": "6000C296-24cf-80d2-e692-67a938ad036c",
                "capacity": 24117248,
                "file_name": "[datastore1] centos7-bios/centos7-bios_3-000009.vmdk",
                "change_id": "52 6a de 0a 18 b4 2a 63-46 54 19 ad 07 88 bd 16/21",
                "system_disk": false,
                "migrate": true
            }
        ],
        "architecture": "x86_64",
        "platform": "CentOS",
        "migrate": true,
        "hardware_version": 19,
        "host_version": "7.0.3",
        "snapshot_state": true

Configure the properties of the VM, such as the operating system, disks, and migration status. You may need to edit the following content:
- platform: The operating system type of the VM. If the automatically detected operating system type is inconsistent with the actual one, you must configure it manually. The following operating system types are supported for migration. Other operating system types are not supported.
- disk: The list of disks for the VM, in array format.
  - The system disk is the first disk by default, and its corresponding system_disk value is true. If the VM's system disk is not the first disk, change the system_disk value for the actual system disk to true and the system_disk value for all other data disks to false.
  - The migrate value for all disks is true by default, which means the disk needs to be migrated. If you do not need to migrate a specific data disk, you can change its corresponding migrate value to false.
- migrate: Whether to migrate the VM.
  - For the selected VM, the migrate value is true, which means the VM needs to be migrated.
  - To migrate a VM whose migrate value is false, you can change the migrate value to true and manually configure platform and architecture.
  - architecture is the architecture of the VM. The valid values are x86_64, i386, and arm64.

Import the migration source

In the VMware agentless connector, run the SMC client from the command line and import the VMware VM information into the SMC console.

Warning

Accidental snapshot deletion
While the SMC client is running, do not manually shut down, restart, or perform snapshot operations, such as creating or deleting snapshots, on the VMware VM to be migrated. If you create or delete snapshots on the VMware VM to be migrated, the migration may fail. If the migration fails for this reason, run ./dist/migrate_configure in the SMC client home directory /root/smc to re-retrieve the VM configuration. Then, run the ./go2aliyun_client --rerun command to restart the SMC client.
Manually delete residual snapshots
During the synchronization phase of the migration task, the SMC client automatically creates a snapshot for the VMware VM to be migrated. The snapshot is named in the format "smc_MigrationTaskID_CurrentTime", for example, smc_j-bp1ho******4_2025-07-02-17:05:43. The snapshot is automatically deleted after synchronization is complete. If you manually delete the migration task before synchronization is complete, residual snapshots may remain. You can resolve this issue as follows:
- Step 1: Manually delete the snapshot
  Manually delete the snapshot in the vCenter/ESXi management interface. Right-click the VM to be migrated, choose Snapshots > Manage Snapshots, select the snapshot, and click DELETE.
- Step 2: Run the following commands to re-retrieve the VM configuration in the SMC client home directory and restart the SMC client.
```
cd /root/smc
./dist/migrate_configure    # Re-obtain the VM configuration
./go2aliyun_client --rerun   # Restart the SMC client
```

Go to SMC console - Agentless Migration of VMware VMs.
On the Agentless Migration of VMware VMs page, click Import Migration source.

Configure the parameters on the Import Migration Source page.

The following table describes the parameters.

Parameter	Description
Migration Source Type	VMware VM.
Import Method	Use Server Migration Connector to Import VMware VM is selected by default and cannot be changed.
Description	Follow the import instructions to import the migration source.

Obtain an activation code.
1. Obtain an activation code (recommended): An SMC activation code, also known as an Access Token, consists of an Access Token ID and an Access Token Code. To obtain a code, click Generatein the Description section of the SMC console and copy it.
2. Log on to the VMware agentless connector and run the following commands in sequence to import the migration source.
```
chmod +x ./go2aliyun_client
./go2aliyun_client
```
  Enter the activation code as prompted. This example uses an activation code. The output is similar to the following. When the message Import Source Server [s-bp14zd35128xgjdbh****] Successfully! appears, the migration source has been imported successfully.
  Note
  - Run ./go2aliyun_client --help to obtain help information.
  - If importing the migration source fails due to an incorrect activation code, you can re-import it. The command is ./go2aliyun_client --accesstokenid=at-****** --accesstokencode=yK******9I.
  - You can also activate the SMC client using 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 an AccessKey pair, create one first. For more information, see Create an AccessKey pair. The command is ./go2aliyun_client --accessid=****** --secretkey=******9I.
3. On the Agentless Migration of VMware VMs page in the SMC console, you can check the status of the migration source in the Real-time Migration Status column.
  - A status of Migration SourceOnline indicates a successful import.
  - If the status is not Source Online, the import failed. Troubleshoot the issue using the following methods and then re-import the source.
    - Resolve the issue based on the error message in the console or by checking the log files in the SMC client directory. The default installation directory for the SMC client is C:\smc.
    - For common issues and solutions, see SMC FAQ and Troubleshooting.

Step 3: Create a migration task

In the SMC console, follow the on-screen instructions to create and start a migration task. SMC supports migrating VMware servers to the destination types listed under Destination Type:

(Recommended) ECS Image: Migrates the server to a custom image. You can then use the custom image to create an ECS instance.
ECS Instance: You can migrate a VMware VM to a new ECS instance or to an existing ECS instance if its data is no longer needed. However, the number and size of storage volumes, the operating system, and other configurations of the VMware VM must be compatible with the target ECS instance.
Warning
After you create the migration task, the original data on the destination ECS instance is cleared. The data on the source server is not cleared. If the ECS instance contains important data, do not use this migration method.

Go to SMC console - Agentless Migration of VMware VMs.
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	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. 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.
Execution Method	Select an execution method for the migration task: 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. Note This feature is not supported if you choose to migrate to a Destination Instance. 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 run periodically and synchronize incremental data to Alibaba Cloud. For more information about best practices for incremental migration, see Agentless incremental migration for VMware VMs.
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 a VPC to a data center or another 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.

Configure disk parameters. The following table describes the parameters.

Parameter

Description

Destination Disk Size (GiB)

Set the disk structure of the destination ECS server. Configure the parameters based on your business needs:

System Disk

The size of the system disk for the destination Alibaba Cloud ECS server, in GiB. The value range for the system disk size is 20 to 2048. The destination system disk size must be greater than the source system disk size. For example, if the source system disk size is 400 GiB, the destination system disk size must be greater than 400 GiB.

Note

The default value is the size of the source system disk. If you do not need to reduce the system disk capacity, do not set it to a value smaller than the default.

Data Disk

Data Disk <N>: The size of the data disk for the destination Alibaba Cloud ECS server after migration, in GiB. The value range for the data disk size is 20 to 32768.

The variable <N> represents the data disk number.
The data disk size must be greater than the source data disk size. For example, if the source data disk size is 500 GiB, the destination data disk size must be greater than 500 GiB.

Note

If your migration source does not have a data disk, or the data disk is not mounted, the Data Disk configuration item will not appear. For more information, see Why does the data disk configuration item not appear on the new migration task page?.

(Optional) To set advanced parameters, such as the network mode and compression ratio, click Advanced Settings. The following table describes these parameters.

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.
Transmission Mode	Automatic: Default. This mode selects the best available transmission mode. LAN: This mode uses local area network (LAN) transmission. It requires that the VMware agentless connector VM can access the ESXI of the VM to be migrated via the LAN. LAN-Free: This mode uses storage network transmission. It requires that the VMware agentless connector VM and the VM to be migrated are on the same ESXI.
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 Agentless Migration of VMware VMs page, you can view the migration status.
The time required for data transmission depends on factors such as the source data size and network bandwidth. Wait for the migration task to complete.
When the migration task status is Synchronizing, you can click Pause Migration Job in the Actions column to pause the task.
(Optional) View migration details.
In the Migration Source ID/Name column, click a migration source ID to view its details.

Verify the migration result

The migration is complete when the Real-time 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 the system after a Linux server is migrated? or How do I check the system after a Windows server is migrated?.
- 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 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.

References

Incremental migration
To migrate incremental data multiple times, after the first full migration is complete, you can perform multiple incremental migrations at custom intervals. This synchronizes the incremental data generated by the source server system to Alibaba Cloud, effectively reducing business downtime and final cutover time. For more information, see Agentless incremental migration for VMware VMs.
ECS server migration guide
Alibaba Cloud provides various ways to migrate servers to the cloud and within the cloud, such as migrating on-premises physical machines to Alibaba Cloud, migrating Tencent Cloud servers to Alibaba Cloud, and migrating ECS instances between accounts in Alibaba Cloud. You can choose the appropriate migration method based on your specific business scenario. For more information, see ECS server migration guide.
SMC also provides the following migration capabilities:
The SMC client is a migration tool developed by Alibaba Cloud. You need to run the SMC client on the source server during migration. For more information, see SMC client user guide.
Error S11: Network connection error with the intermediate service on the destination instance during migration

Server Migration Center:Agentless migration for VMware VMs

Migration scenarios

Limits

Environment requirements

Supported operating systems

Disk size limits

Role permission requirements

Migration fees

Prerequisites

Procedure

Step 1: Create a VMware agentless connector

Download and decompress the OVA template

Deploy the VMware agentless connector

Deploy in vCenter (Recommended)

Deploy in a standalone ESXi environment

Step 2: Import the migration source

Add VMs to be migrated (multiple VMs are supported)

(Optional) Configure the VMs to be migrated

Import the migration source

Step 3: Create a migration task

ECS Image

ECS Instance

Public Network (Default)

VPC

System Disk

Data Disk

Verify the migration result

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

References