Wednesday, 20 June 2012

Linux Real Time Issues-2


I migrate to RHEL6.2 and now I have problem initialization network cards.
My problem is :

I installed OS as a server and when I want to configure the network, I see there are 4 connections for example :
eth0 ,eth1,eth2,eth3.
And when I place these Hard disk(has this version of OS6.2) on to another HP Server or HP Blade.
And when system restart, the network shows:
eth4, eth5,eth6, eth7
It shows that the system remain the previous network configuration somewhere
when I delete all of them and reconfigure again, it shows again number 4,5,6,7.
I configured net devices on /etc/sysconfig/networking/devices
with the name ifcfg-eth0,ifcfg-eth1,ifcfg-eth2,ifcfg-eth3 with static IP,,,
and when I restart service NetworkManager
some of my device name doesn't change.
I found that the uuid and HWADDR stay in configuration file .and for example on my server when I config the server as the same as above and run ifconfig:
I saw eth0 and eth3 but the eth6, eth7 doesn't change.
I need the urgent help.
Please help me to solve.
I need to setup network connection on Blade servers with 4 connection
for DB.



1.Network-Manager configure it?

2.I have seen this happen while cloning centos 6.x virtual machines.

The problem is that udev caches the mac addresses of the nic cards so when
you swap the disks to a new box. It sees them as new devices and assigns
new the numbers.

I believe I was able to keep this from happening by removing the mac
addresses from the /etc/sysconfig/network-scripts/ifcfg-eth* files and
then when booting the cloned vm up for the first time (or in your case, the
other blade), boot to single user mode, remove (or rename)

Then reboot again. udev should recreate the 70-persistent-net.rules file
with the new mac addresses and use them as eth0, eth1, eth2 and eth3.


Thanks a lot for your guidance. I saw the path you had been referred to it and now I'm trying on some servers. One server on Blade and the other on HP DL380.
I'm trying. I hope I can start network connection correctly.


I could change the /etc/udev/rules.d/70*net.rules
but when I change the network connection on Blade system the device number would changed too. For example eth0 --> eth4 and so on..
Also it seem there is somewhere in configuration files that limited us that only 1 or 2 connection can be talk to each other on different servers.
Now I configured networks connections 4 address,,, and on the other server I set the network as :
but only ip range 4 can ping each other I also disable iptables, but the other connections don't ping each others

4.hese are not packages - these are the flatfiles Linux uses to manage the
network interfaces.

For each of your network cards, you should have a file under

One of mine off a Centos 6 box looks like:

cb6 obsr> cat /etc/sysconfig/network-scripts/ifcfg-eth0

To make the OS drives "portable" between machines, try editing out the
HWADDR - put a # in front of it.
Then try removing the udev file and reboot - since your ifcfg-eth# files
are no longer bound to the mac addresses, udev should reassign them as

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