HI,I am so novice in CentOs,And I have a big problem
The network connection has been disconnected and I do not why
When I want to restart my network I have this error

[root@centos1 AAA]# service network restart
Shutting down interface eth0: [ OK ]
Shutting down loopback interface: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0:
Determining IP information for eth0... done.
[ OK ]
Bringing up interface eth0.save: Error: Connection activation failed: Device not managed by NetworkManager or unavailable
[FAILED]

It seems to me that your eth0 is brought up ok?
"Bringing up interface eth0:
Determining IP information for eth0... done.
[ OK ]"
But you have a second config file named "/etc/sysconfig/network-scripts/ifcfg-eth0.save", this interface "eth0.save" is the one that can't be brought up. As it's name suggests it is only a backup of ifcfg-eth0, I suggest you move or delete it.
You see, all config files named "/etc/sysconfig/network-scripts/ifcfg-<anything>" are treated as legitimate interface scripts, causing system to try to activate the interface <anything>.
---
Edit, more accurately:
"...causing system to try to activate the interface specified in the file ifcfg-<anything>."

1 members found this post helpful.

Thanks a million
It works now