Setting an LCS group device online or offline

Red Hat Enterprise Linux 9.2 LPAR mode z/VM guest

Use the online device group attribute to set an LCS device online or offline.

About this task

Setting a device online associates it with an interface name. Setting the device offline preserves the interface name.

You must know the interface name to activate the network interface. To determine the assigned interface name, use the lszdev --existing command. For each online interface, the interface name is shown in the Name column.

Alternatively, for each online interface, there is a symbolic link of the form /sys/class/net/<interface_name>/device in sysfs. You can confirm that you found the correct interface name by reading the link.

Procedure

To set an LCS group device online, set the online device group attribute to 1. To set an LCS group device offline, set the online device group attribute to 0.

Issue a command of this form:

# echo <flag> > /sys/bus/ccwgroup/drivers/lcs/<device_bus_id>/online

Example

To set an LCS device with bus ID 0.0.d000 online issue:

# echo 1 > /sys/bus/ccwgroup/drivers/lcs/0.0.d000/online
# lszdev --existing
TYPE         ID                          ON   PERS  NAMES
...
lcs          0.0.d000:0.0.d001           yes  no    encd000
...

The interface name that was assigned to the LCS group device in the example is encd000. To confirm that this name is correct for the group device issue:

# readlink /sys/class/net/encd000/device
../../../devices/lcs/0.0.d000

If an error occurs when you set the device online, ensure that the physical connection from the port to the network is in place. If the error persists, note the return code from the error message and contact IBM® support.

To set the device offline issue:

# echo 0 > /sys/bus/ccwgroup/drivers/lcs/0.0.d000/online