What do I do if a Linux operating system fails to be migrated due to unstable naming schemes for NICs? - Server Migration Center

This topic describes the cause of the "Unsupported network configuration" error message that is reported when you use Server Migration Center (SMC) to migrate an operating system. This topic also describes how to resolve the error.

Problem description

During the migration of an operating system, the "Unsupported network configuration" error message is reported.

Cause

Unstable naming schemes for network interface controllers (NICs) such as eth0 and eth1 are used in the current operating system. These naming schemes cannot ensure naming reliability after the operating system is updated. This may cause network disconnections after the migration and lead to migration failure.

Solution

Set the net.ifnames parameter to 0 to ensure that the eth naming scheme is used for NICs after the migration. This parameter is a kernel startup parameter.

Connect to the Elastic Compute Service (ECS) instance whose operating system you want to migrate. For more information, see Connect to a Linux instance by using a password or key.
Run the following command to view the NIC driver:
```
ethtool -i eth0 | grep driver
```
A command output similar to the following one is returned:
```
ethtool -i eth0 | grep driver
driver: virtio_net
```
Check whether the net.ifnames parameter exists and is set to 0 in the kernel startup parameter configurations.
```
cat /proc/cmdline | grep "net.ifnames=0"
```
If the net.ifnames parameter does not exist or is set to a number other than 0, perform the following steps to modify the kernel startup parameter configurations.
Modify the kernel startup parameter configurations.
1. Run the following command to edit the /etc/default/grub file:
```
vim /etc/default/grub
```
2. Press the I key to enter the insert mode.
3. Add net.ifnames=0 to the line in which the GRUB_CMDLINE_LINUX field is located.
```
GRUB_CMDLINE_LINUX="crashkernel=auto spectre_v2=retpoline rhgb quiet console=tty0 console=ttyS0,115200n8 noibrs nvme_core.io_timeout=4294967295 nvme_core.admin_timeout=4294967295 net.ifnames=0"
```
4. Press the Esc key to exit the insert mode. Enter :wq and press the Enter key to save and close the file.
5. Run one of the following commands to generate the grub.cfg file based on your boot mode and refresh the kernel startup parameter configurations.
  - Legacy boot mode:
```
grub2-mkconfig -o /boot/grub2/grub.cfg
```
  - Unified Extensible Firmware Interface (UEFI) boot mode:
```
grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
```
6. Run the following command to restart the operating system:
```
reboot
```
Connect to the ECS instance whose operating system you want to migrate. For more information, see Connect to a Linux instance by using a password or key.
Run the following command to check whether the net.ifnames parameter exists and is set to 0 in the kernel startup parameter configurations:
```
cat /proc/cmdline
```
If the net.ifnames parameter exists and is set to 0, the modification of the kernel startup parameter configurations is successful.
Run the following command to disable the naming detection of NICs.
In this case, the eth naming scheme is used for the NICs after the operating system is updated. This prevents issues related to the naming order. Therefore, the naming detection of NICs can be disabled.
```
mv /usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/persistentnetnamesdisable /tmp
```
After the error is resolved, run the SMC client and retry the migration job. For more information, see Run the SMC client.