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).
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.