Problem Diagnosis - Expert Oracle RAC Performance Diagnostics and Tuning - page 628

When servers are running slow and there are users complaining of slow sessions, ORADEBUG
helps the DBA collect session trace information for user sessions:

3.

sqlplus '/as sysdba'
sqlplus> oradebug setospid 7010
sqlplus>oradebug event 10046 trace name context forever, level 12
sqlplus>
sqlplus '/as sysdba'
sqlplus> oradebug setospid 7010
sqlplus> oradebug event 10046 trace name context off
sqlplus>

In the preceding output, 10046 trace is collected for session 7010 by setting the operating system process
identifier (OSPID) to the current session.

4. Several times when critical issues arise in a production environment and the management

keeps looking over the shoulders of the DBA to get the database up, the DBAs do not have
sufficient time to do any preliminary investigation. Under these circumstances or when
additional information needs to be dumped from the memory structures of Oracle, it could
be useful to freeze the instance and dump out instance information for analysis later.

By invoking the flash freeze feature available from ORADEBUG, DBAs can take a diagnostic snapshot of the entire
system at the time of failure and quickly restart the database. This helps to complete the analysis offline:

SQL> oradebug ffbegin
Statement processed.

FFBEGIN (flash freeze begin) will freeze the database instance, including all background processes. When this
command is issued, the database will record the freeze information in the alert log:

Fri Dec 17 18:01:27 2010
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20344, image: oracle@prddb1 (PMON)
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20346, image: oracle@prddb1 (PSP0)
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20348, image: oracle@prddb1 (VKTM)
Error (ORA-00072) failed to issue ORADEBUG FFBEGIN to: Unix process pid: 20348, image: oracle@prddb1
(VKTM)
Errors in file /app/oracle/diag/rdbms/prddb/PRDDB_1/trace/PRDDB_1_ora_23646.trc:
ORA-00072: process "VKTM" is not active
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20352, image: oracle@prddb1 (GEN0)
Fri Dec 17 18:01:27 2010
Unix process pid: 20344, image: oracle@prddb1 (PMON) flash frozen [ command #1 ]
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20354, image: oracle@prddb1 (DIAG)
Fri Dec 17 18:01:27 2010
Unix process pid: 20346, image: oracle@prddb1 (PSP0) flash frozen [ command #1 ]
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20356, image: oracle@prddb1 (DBRM)
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20358, image: oracle@prddb1 (PING)
Issuing ORADEBUG FFBEGIN to: Unix process pid: 20360, image: oracle@prddb1 (ACMS)
Unix process pid: 20701, image: oracle@prddb1 (TNS V1-V3) flash frozen [ command #1 ]
Fri Dec 17 18:01:27 2010
Unix process pid: 20747, image: oracle@prddb1 (CJQ0) flash frozen [ command #1 ]
Fri Dec 17 18:01:27 2010
Unix process pid: 20706, image: oracle@prddb1 (TNS V1-V3) flash frozen [ command #1 ]