Archive for March, 2014

DOAG Würzburg: “Resolving child cursor issues resulting in mutex waits”

I feel honored that DOAG asked me once more for being a speaker at an event – this time it’s DOAG Regionalgruppe Würzburg. I will give my (updated) C12LV and Oracle Open World 2012 talk “Resolving child cursor issues resulting in mutex waits” there, supported by my new business Performing Databases GmbH.

My abstract:
In special situations, the Oracle Database generates too many child cursors for particular SQL-IDs. This results in high CPU load on the DB server, coming from heavy mutex access. This is visible as mutex wait events. The lecture will show how this situation arises, how the DBA can try to quick-fix it and how long-term solutions can be found. Additionally, we will have a closer look on the Oracle internal situation: Why does the DB use mutexes here, and how?

Thursday (Donnerstag) 27.03.2014
5 p.m. (17 Uhr)

Würzburger Versicherungs AG
Bahnhofstraße 11
97070 Würzburg

The presentation will be available after the talk at and on the DOAG online-resource page.

By Martin Klier in Community,DOAG,Lectures,Oracle  .::. (Add your comment)

Oracle Dataguard: ORA-00600 [krsu_upi_atc.7] – crash when primary ships the first time

After setting up a new Oracle Dataguard system (primary plus one standby DB), everything looked promising.

But after activating the log shipping from primary, and after archiving a redo log for the first time, the primary instance crashed with ORA-00600 [krsu_upi_atc.7]. Without the standby system available (DB idle or listener off), no error occurred.

 LGWR: Setting 'active' archival for destination LOG_ARCHIVE_DEST_2
 LGWR: Archival destination is a Primary RAC instance: 'ITWMT2'
 Errors in file /u01/app/oracle/diag/rdbms/itwmt/ITWMT/trace/ITWMT_lgwr_22151.trc  (incident=18089):
 ORA-00600: internal error code, arguments: [krsu_upi_atc.7], [], [], [], [], [], [], [], [], [], [], []
 Incident details in: /u01/app/oracle/diag/rdbms/itwmt/ITWMT/incident/incdir_18089/ITWMT_lgwr_22151_i18089.trc
 Use ADRCI or Support Workbench to package the incident.
 See Note 411.1 at My Oracle Support for error and packaging details.
 Errors in file /u01/app/oracle/diag/rdbms/itwmt/ITWMT/trace/ITWMT_lgwr_22151.trc:
 ORA-00600: internal error code, arguments: [krsu_upi_atc.7], [], [], [], [], [], [], [], [], [], [], []
 LGWR (ospid: 22151): terminating the instance due to error 470
 Wed Mar 19 15:27:07 2014
 ORA-1092 : opitsk aborting process
 Wed Mar 19 15:27:07 2014
 System state dump requested by (instance=1, osid=22151 (LGWR)), summary=[abnormal instance termination].
 System State dumped to trace file /u01/app/oracle/diag/rdbms/itwmt/ITWMT/trace/ITWMT_diag_22141_20140319152707.trc
 Dumping diagnostic data in directory=[cdmp_20140319152707], requested by (instance=1, osid=22151 (LGWR)), summary=[abnormal instance termination].
 Instance terminated by LGWR, pid = 22151

Instance terminated by LGWR did not look promising. Plus no search-engine-of-choice hits, no MOS search result. But re-reading the configuration unveiled a very basic mistake: The DB_UNIQUE_NAME of the two databases (primary and standby) was the SAME – not exactly the purpose of a UNIQUE name…. Changing it on standby side, and off it went.

Let me tell you, read carefully.
Martin Klier

By Martin Klier in Oracle  .::. (Add your comment)

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