Tracing LMS processes ( or any other RAC background process ) using DBMS_SYSTEM.set_ev Select sid, serial# process from gv$session SQL> select inst_id,sid, serial#, program from gv$session where program like '%LMS%' and INST_ID=3; INST_ID SID SERIAL# PROGRAM ---------- ---------- ---------- ------------------------------------------------ 3 66 1 oracle@grac43.example.com (LMS0) 3 128 1 oracle@grac43.example.com (LMS1) Connect to instance 3 and enable tracing for LMS0 and LMS1 process SQL> EXEC DBMS_SYSTEM.set_ev(si=>66 ,se=>1, ev=>10046, le=>12, nm=>''); SQL> EXEC DBMS_SYSTEM.set_ev(si=>128 ,se=>1, ev=>10046, le=>12, nm=>''); Check for tracefile grac43_lms0_XXX and grac43_lms1_XXX in your trace directory and display wait events by suppressing "gcs remote message" messages # cat grac43_lms0_7493.trc | grep -v "gcs remote message" *** 2014-02-11 10:15:08.807 WAIT #0: nam='gcs log flush sync' ela= 2722 waittime=30 poll=0 event=138 obj#=0 tim=1392110108814702 Disable tracing: EXEC DBMS_SYSTEM.set_ev(si=>66 ,se=>1, ev=>10046, le=>0, nm=>''); EXEC DBMS_SYSTEM.set_ev(si=>128 ,se=>1, ev=>10046, le=>0, nm=>'');