bonding – write error – device or resource busy – operation not permitted

Recently, there was a little bit of confusion when following the article about activating network bonding without ifenslave – How to enable Linux bonding without ifenslave. At first, there were couple of errors:

livecd ~ # echo balance-alb > /sys/class/net/bond0/bonding/mode
-bash: echo: write error: Device or resource busy
livecd ~ # echo "+enp129s0f0" > /sys/class/net/bond0/bonding/slaves
-bash: echo: write error: Operation not permitted

Or similar error when changing the bonding mode:

livecd ~ # echo 4 > /sys/class/net/bond0/bonding/mode
-bash: echo: write error: Directory not empty
livecd ~ # echo 802.3ad > /sys/class/net/bond0/bonding/mode
-bash: echo: write error: Directory not empty

The server just booted in rescue live cd and there is no active network configuration:

SCREENSHOT 1) Apparently, the /sys/class/net/bond0/bonding/mode and /sys/class/net/bond0/bonding/slaves are in read only state.

No writes means no new configuration could be installed and the bonding cannot be configured (reconfigured).

main menu
device or resource busy – operation not permitted

Bonding mode could be changed only when the bonding device is in DOWN state.

Network interfaces could be added to the boding device only if they were in DOWN state, too.

In addition, changing bonding mode could only happen if there were no network interfaces added to the bonding interface.

Keep on reading!

How to enable linux bonding without ifenslave

ifenslave is no more needed when configuring bonding under Linux. There are situations when we could have no network link without bonding, because of specific switch configuration and we do not have ifenslave package installed. We can configure bonding manually via Sysfs.
Here are the steps to configure bond0 in adaptive load balancing with two network cards in slave mode:

modprobe bonding
echo balance-alb > /sys/class/net/bond0/bonding/mode
echo +eth0 > /sys/class/net/bond0/bonding/slaves
echo +eth1 > /sys/class/net/bond0/bonding/slaves
ifconfig bond0 netmask up

The adaptive load balancing does not require any special network setup. On the contrary, the mode “802.3ad” could be used only if you enable bonding of the interfaces of your server to have a network link.

echo 802.3ad > /sys/class/net/bond0/bonding/mode

For more detailed explanation:

If the “/sys/class/net/bond0” is missing you should do:

echo +bond0 > /sys/class/net/bonding_masters