How can I enable or disable debug on Control-M/Server processes?

It is recommended to consult with BMC Support first, before setting any debug

A.  Interactive option:
Login to the Control-M Configuration Manager within Control-M/Enterprise Manager
Right-click on the desired Control-M/Server
Select Control-M Server Debug to view the current debug levels
Set the desired Debug Level (typically 4)
Click Apply
Click Ok

B.  Command line option directly on Control-M Server:

1. View Current debug levels.
   • Open a command prompt as the Control-M/Server user
   • Run either of the following commands:

ecaprflag -ACTION LIST

prf 1 1

The last column "DIAG_LVL" will show the debug level (0 = Disabled)

For example,
PROCNAME PROCID     PROCSTAT PSTAT_REQ SLEEP_TIME DIAG_LVL
CE                21364958  R                 R                   60                  0
NS                19267736  R                 R                   30                  0
RT                7536752    R                 R                   30                  0
SU                5046418    R                 R                   60                  0
TR                23920842  R                 R                   5                    0
WD               20840502  R                 R                   360                0

• Open a command prompt as the Control-M/Server user
•  Run the dbglvl command
  • Syntax:  dbglvl process_name debug_level [module_number]
• Examples (typically the first value for debug_level is set to 4 and module_number is set to 0):
  • dbglvl CE 4 0
  • dbglvl SU 4 0
  • dbglvl TR 4 0
  • dbglvl UT 4 0
  • dbglvl ALL 4 0

3. Disable debug on the Control-M Server

• Examples:
  • dbglvl ALL 0 0
  • dbglvl SU 0 0
  • dbglvl CE 0 0
  • dbglvl TR 0 0

NOTE: Debug can also be set via the ctm_menu utility via option 8. Troubleshooting -> 1. Set Diagnostic Levels

C. Enabling Debug may have a great impact on the performance of Control-M/Server

To reduce the performance impact of debug one can enable FAST_DIAG mode by setting this variable to Y in ~/ctm_server/data/config.dat and recycling Control-M/Server
By default, FAST_DIAG is set to N on Unix and is set to Y on Windows.
This parameter by default is not included in the ~/ctm_server/data/config.dat file
When added FAST_DIAG keyword to this file it will overwrite the default behavior 

Setting to Y on Unix will prevent the application from opening and closing the debug log files for every line output.
Performance-wise, enabling FAST_DIAG will greatly improve CTMS throughput on Unix platforms.
Therefore if debugging CTMS and you see that it is having a serious impact on performance one should insert FAST_DIAG in config.dat and set it to Y. The processes need to be recycled for this change to take effect.
The drawback to enabling FAST_DIAG is that one should shut CTMS to flush the write buffer and close the log file before moving the proclog files otherwise one may lose the last few minutes of the debug.