Logging I/O subchannel status information
When investigating I/O subchannels, support specialists might request operation status information for the subchannel.
About this task
The channel subsystem offers a logging facility that creates a set of log entries with such information. You can trigger this logging facility through sysfs.
The log entries are available through the SE Console Actions Work Area with the View Console Logs function. The entries differ dependent on the device and model that is connected to the subchannel. On the SE, the entries are listed with a prefix that identifies the model. The content of the entries is intended for support specialists.
Procedure
To create a log entry, issue a command of this form:
# echo 1 > /sys/devices/css0/<subhannel-bus-id>/loggingwhere <subchannel-bus-id> is the bus
ID of the I/O subchannel that corresponds to the I/O
device for which you want to create a log entry.
To find out how your I/O devices map to subchannels you can use, for example, the lscss command.
Example
In this example, first the subchannel for
an I/O device with bus ID
0.0.3d07 is identified,
then logging is initiated. # lscss -d 0.0.3d07
Device Subchan. DevType CU Type Use PIM PAM POM CHPIDs
----------------------------------------------------------------------
0.0.3d07 0.0.000c 1732/01 1731/01 80 80 ff 05000000 00000000
# echo 1 > /sys/devices/css0/0.0.000c/logging