When debugging, being able to configure the log level so that just commands for a particular device are logged would be helpful. Often several devices are attached, but only one device causes issues. Log messages for other devices make it hard to evaluate the log output. Thus the rascsi -L option shall be extended with an optional device ID and LUN like this:

-L trace[:ID:[LUN]]

The LOG_LEVEL operation of the protobuf interface should be extended with two optional "id" and "lun" parameters. If this is not possible in a backwards compatible way it is sufficient to just offer the new logging settings in rascsi, because this feature is mainly relevant for debugging on the command line.