Device eth0 does not seem to be present, delaying initializa

Fault analysis:
When the machine is changed, the mac address of the NIC is changed. This problem is caused by udev.

Solution:
Method 1:
You can modify/etc/udev/rules against the existing mac address. d/The 70-persistent-net.rules file in the directory (the name may be different). Replace the MAC address of the ethx with the existing MAC address.

The second method is the simplest and recommended by bloggers:
# Rm-f/etc/udev/rules. d/70-persistent-net.rules
# Reboot
After the restart, the system automatically generates the 70-persistent-net.rules file.

This article is based on the CentOS 6.3 Environment, it is also possible to directly comment out the MAC address in/etc/sysconfig/network-scripts/ifcfg-ethx on the 5.x host.