Incrementing/Decrementing the Trace Level 
Use this procedure to increment/decrement the trace level for the developer trace files (dev_jcontrol, dev_<component name>) of the processes. By default, the trace level is set to 1. In some critical cases and in problem analysis, we recommend that you increase the trace level to log more information in the developer trace files.
The value range of the trace level property can be between 0 (lowest) and 3 (highest):
0: No trace
1: Write error messages in the trace file.
2: Full trace. The trace entries that are actually written can vary with the program that is being traced.
3: Additionally, trace data blocks.
Procedure
Start the SAP Management Console (SAP MMC under Windows, SAP MC under UNIX).
Select a process from the process list.
From the context menu, choose one of the following:
To increment the trace level,
All
Tasks 
Increase trace level (signal URS2)
To decrement the trace level,
All
Tasks Decrease trace level (signal URS1)
To view the trace file, choose Developer Trace from the context menu.
Alternatively, you can send the signals USR2 and —USR1 to a process from the command line using the kill (UNIX) or the sapntkill (Windows) command.
Example
kill —USR2 <pid> increases the trace level of the UNIX process with the process ID <pid>.