Hanganalyze and Systemstate

Collection commands for Hanganalyze and Systemstate: Non-RAC:

Sometimes, database may actually just be very slow and not actually hanging. It is therefore recommended,  where possible to get 2 hanganalyze and 2 systemstate dumps in order to determine whether processes are moving at all or whether they are "frozen".

Hanganalyze

sqlplus '/ as sysdba'

oradebug setmypid

oradebug unlimit

oradebug hanganalyze 3

-- Wait one minute before getting the second hanganalyze

oradebug hanganalyze 3

oradebug tracefile_name

exit

Systemstate
sqlplus '/ as sysdba'

oradebug setmypid

oradebug unlimit

oradebug dump systemstate 266

oradebug dump systemstate 266

oradebug tracefile_name

exit

 

Collection commands for Hanganalyze and Systemstate: RAC

There are 2 bugs affecting RAC that without the relevant patches being applied on your system, make using level 266 or 267 very costly. Therefore without these fixes in place it highly unadvisable to use these level

For information on these patches see:

Document 11800959.8 Bug 11800959 - A SYSTEMSTATE dump with level >= 10 in RAC dumps huge BUSY GLOBAL CACHE ELEMENTS - can hang/crash instances 

Document 11827088.8 Bug 11827088 - Latch 'gc element' contention, LMHB terminates the instance 

  

Note:  both bugs are fixed in 11.2.0.3.

  

Collection commands for Hanganalyze and Systemstate: RAC with fixes for bug 11800959 and bug 11827088
For 11g:

sqlplus '/ as sysdba'

oradebug setorapname reco

oradebug  unlimit

oradebug -g all hanganalyze 3

oradebug -g all hanganalyze 3

oradebug -g all dump systemstate 266

oradebug -g all dump systemstate 266

exit

Collection commands for Hanganalyze and Systemstate: RAC without fixes for Bug 11800959 and Bug 11827088

sqlplus '/ as sysdba'

oradebug setorapname reco

oradebug unlimit

oradebug -g all hanganalyze 3

oradebug -g all hanganalyze 3

oradebug -g all dump systemstate 258

oradebug -g all dump systemstate 258

exit
For 10g, run oradebug setmypid instead of oradebug setorapname reco:

sqlplus '/ as sysdba'

oradebug setmypid

oradebug unlimit

oradebug -g all hanganalyze 3

oradebug -g all hanganalyze 3

oradebug -g all dump systemstate 258

oradebug -g all dump systemstate 258

exit

In RAC environment, a dump will be created for all RAC instances in the DIAG trace file for each instance.