Re-naming Network Interfaces on Red Hat 6

If you've ever needed to use a certain network interface on a linux (specifically RHEL6 here) you'll notice there are several different ways to do it.  A search of the interwebs will give you numerous avenues but I'm going to outline the one here which worked for me. We'll use ifcfg-em1 and ifcfg-em2 for these examples and assume you have console access.

Symptoms: one of your nics has died and the software on the server is dependent on the interface name. i.e. Oracle RAC

First you will need to reboot afterwards, there was no way around it for myself.  Give yourself that luxury instead of thinking you can just do a <code> service network restart </code> to finish it. Start by creating backups of ifcfg-em1 and ifcfg-em2. Rename ifcfg-em1 to ifcfg-em3 and then ifcfg-em2 to ifcfg-em1.

Next create a file if it does not exist already of "/etc/udev/rules.d/70-persistent-net.rules".  If it does not exist you can attempt to create it using the automated tool of "/lib/udev/write_net_rules all_interfaces".  This method did not work for me and I had to create the file manually which did work.  *Note you are swapping the MAC addresses here and putting what you WANT em1 and em2 to be.

</etc/udev/rules.d/70-persistent-net.rules>
 # PCI device 0x14e4:0x163a (bnx2) (custom name provided by external tool)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:11:22:33:44:55", ATTR{type}=="1", KERNEL=="em*", NAME="em1"

# PCI device 0x14e4:0x163a (bnx2) (custom name provided by external tool)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:11:22:33:44:44", ATTR{type}=="1", KERNEL=="em*", NAME="em2"
</etc/udev/rules.d/70-persistent-net.rules>

Once you've confirmed those two things are done reboot the server and it'll come back up proper. Took a lot of searching to get all this set up correctly.  Hope this helps someone else.

Breaking a Bonded interface on RHEL

Today I had to break a bonded interface on a server running RHEL 5.  The bond was not a port channel but rather a fail-over setup.  The end result was to have only eth0 still up but if possible not bring down the box to do it.  Here's how I did it and a link to the original site I pulled it from.  You can also look in the documentation on the box if you don't have the interwebs available at the time.

RHEL Network Bonding

For more reference to use there values you can check, in your linux box :  /usr/share/doc/kernel-doc-2.6.18/Documentation/networking/bonding.txt 

>>>> 3.  How to Gracefully Break the Bonded Network Interface?

In Sample Configuration is we have bond0 configure for two interface name eth0 and eth1, and bond running configuration looks as 

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0  Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 53:44:00:43:91:04
Slave Interface: eth1
MII Status: up
Link Failure Count: 0
Permanent HW addr: 52:33:00:6d:0e:70

The process to break the bonded interface is :

a.  Online remove one slave network interface which will be assigned with a new IP address from the bonding device. In this example, we are going to remove the eth1 from bond0. Execute the following command as root:

# ifenslave -d bond0 eth1
Or
# echo -eth1 > /sys/class/net/bond0/bonding/slaves

After issue the command above , You will see the eth1 device has been remove from bond0 # cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0 
Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr:  53:44:00:43:91:04

b. Create a new network configuration for eth1 via graphic tool or text tool and then using following command to start eth1 again. Make sure the physical link has been changed correctly to match the new network configuration of eth1.

# ifup eth1
During the above 2 steps, the network of bond0 will work fine without any break up.

c. Create the same network configuration as bond0 for eth0 

 – just copy the content of /etc/sysconfig/network-scripts/ifcfg-bondX to  /etc/sysconfig/network-scripts/ifcfg-eth0, except the interface name and HW MAC address.

d. Remove the eth0 from bond0, destory the bond0 device and start eth0 immediately.

Please note this disruptive operation, The network of bond0/eth0 will break shortly during this step. # ifenslave -d bond0 eth0; ifdown bond0; ifup eth0
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.4.0 
Bonding Mode: load balancing (round-robin)
MII Status: down
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
now ifconfig will show the configuration for only eth0 and eth1, no bonding interface appears.

e. Remove all bonding setting of bond0 in /etc/modprobe.conf and remove the ifcfg-bond0 in /etc/sysconfig/network-script directory. Then issue following command to remove the bond0 device from memory completely.

# echo -bond0 > /sys/class/net/bonding_masters

Updating iDRAC firmware from linux

Here are ways to update the firmware on Dell iDRAC6 remote access cards.

Both methods require downloading the BIOS from Dell and extracting it from the bundle. For example, this is the 1.70.21 firmware:
mkdir /tmp/dell
cd /tmp/dell
wget http://ftp.dell.com/esm/IDRAC6_FRMW_LX_R299265.BIN

Grab this and extract like this:
cd /tmp/dell
sh IDRAC6_FRMW_LX_R299265.BIN --extract ./idrac6-1.70.21
The firmware image is now in /tmp/dell/idrac6-1.70.21/payload/firmimg.d6

If using the CMC to update the firmware upload the extracted firmimg file, NOT THE BIN!

If you are just updating one machine, then the simplest way to perform the update is to use the Dell bmcfwul tool locally. This is supplied in the dell_ie_nitrogen package, and is installed to /usr/libexec/dell_dup/dell_ie_nitrogen/bmcfwul.

Install the new firmware like this:
/usr/libexec/dell_dup/dell_ie_nitrogen/bmcfwul -input=/tmp/dell/idrac6-1.70.21/payload/firmimg.d6
If you have several machines to update, the most convenient way to perform the update is with tftp.

First, copy the firmware image to the tftp server, and put it in /tftproot, or wherever the root of your tftp server is located:
scp /tmp/dell/idrac6-1.70.21/payload/firmimg.d6 $ip_of_tftp_server:/tftproot

Then, trigger a firmware upgrade on the machines remotely using either racadm or ssh:
racadm -r host.to.update -u root -p calvin fwupdate -g -u -a $ip_of_tftp_server
or
ssh host.to.update racadm fwupdate -g -u -a $ip_of_tftp_server

http://yo61.com/updating-dell-idrac6-firmware-linux.html