WAIT events in *.trc files

Question

I am seeing the below messages in Oracle trace files in bdump directory and it is keep on appending trace files.
WAIT #0: nam='rdbms ipc message' ela= 2929698 timeout=300 p2=0 p3=0 obj#=-1 tim=2406524259034
WAIT #0: nam='rdbms ipc message' ela= 2929698 timeout=300 p2=0 p3=0 obj#=-1 tim=2406527188804
WAIT #0: nam='rdbms ipc message' ela= 2929700 timeout=300 p2=0 p3=0 obj#=-1 tim=2406530118570
Can somebosy help me to figureout what does it mean?.
Curently database is performing normaly and no erros reported.
Platform is :Oracle 10.2 on AIX 5.3
~Thanks

Answer 1

Here, I see my DBWR process does not have tracing enabled currently :
SQL> !ps -ef |grep dbw
2001      4051     1  0 22:11 ?        00:00:00 asm_dbw0_+ASM
ora10204  4101     1  0 22:12 ?        00:00:00 ora_dbw0_ORT24FS
ora10204  4157  4154  0 22:13 pts/1    00:00:00 /bin/sh -c ps -ef |grep dbw
ora10204  4159  4157  0 22:13 pts/1    00:00:00 grep dbw
SQL> select s.sid, s.serial#, s.sql_trace from v$session s, v$process p
  2  where s.paddr=p.addr
  3  and p.spid=4101;
       SID    SERIAL# SQL_TRAC
       167          1 DISABLEDNow, I enable tracing on DBWR :
SQL> exec dbms_monitor.session_trace_enable(167,1);
PL/SQL procedure successfully completed.
SQL> select s.sid, s.serial#, s.sql_trace from v$session s, v$process p
  2  where s.paddr=p.addr
  3  and p.spid=4101;
       SID    SERIAL# SQL_TRAC
       167          1 ENABLEDI can see a trace file being written to :
ora10204>pwd
/oracle_fs/ora10204/admin/ORT24FS/bdump
ora10204>ls -ltr|tail -3
-rw-r----- 1 ora10204 dba     900 Nov 27 22:12 ort24fs_lgwr_4103.trc
-rw-r----- 1 ora10204 dba 1659410 Nov 27 22:13 alert_ORT24FS.log
-rw-r----- 1 ora10204 dba    6457 Nov 27 22:18 ort24fs_dbw0_4101.trc
ora10204>cat ort24fs_dbw0_4101.trc |head -20
/oracle_fs/ora10204/admin/ORT24FS/bdump/ort24fs_dbw0_4101.trc
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
ORACLE_HOME = /oracle_fs/ora10204/product/10.2.0.4
System name:    Linux
Node name:      linux64
Release:        2.6.18-53.el5
Version:        #1 SMP Sat Nov 10 19:37:22 EST 2007
Machine:        x86_64
Instance name: ORT24FS
Redo thread mounted by this instance: 1
Oracle process number: 5
Unix process pid: 4101, image: oracle@linux64 (DBW0)
*** 2008-11-27 22:15:20.886
*** SERVICE NAME:(SYS$BACKGROUND) 2008-11-27 22:15:20.866
*** SESSION ID:(167.1) 2008-11-27 22:15:20.866
WAIT #0: nam='rdbms ipc message' ela= 625573 timeout=64 p2=0 p3=0 obj#=-1 tim=1199018868033615
WAIT #0: nam='rdbms ipc message' ela= 2930717 timeout=300 p2=0 p3=0 obj#=-1 tim=1199018870984135
WAIT #0: nam='rdbms ipc message' ela= 2930648 timeout=300 p2=0 p3=0 obj#=-1 tim=1199018873915147
ora10204>I disable tracing :
SQL> exec dbms_monitor.session_trace_disable(167,1);
PL/SQL procedure successfully completed.
SQL> select s.sid, s.serial#, s.sql_trace from v$session s, v$process p
  2  where s.paddr=p.addr
  3  and p.spid=4101;
       SID    SERIAL# SQL_TRAC
       167          1 DISABLED
SQL> and see that the trace file is no longer being updated. (Unfortunately, stopping tracing on a process does NOT write any message like "tracing stopped" to the trace file, you have to watch the trace file or run an "fuser" command on Unix/Linux to see if it is still being wrttien to (on Windows, I guess the file would be locked by the process if tracing hasn't been disabled).
Hemant K Chitale
http://hemantoracledba.blogspot.com