Wednesday Jul 01, 2015

Log Writer Slave Issues in 12.1.0.2 - mainly on IBM AIX

Currently we see a lot of issues with the Multiple Logwriter feature in Oracle Database 12.1.0.2, especially on the IBM AIX platform.

What are Multiple LGWRs?

You will see multiple LGnn (Log Writer Worker) processes on multiprocessor systems, The LGWR (Log Writer) creates worker processes (slaves) to improve the performance of writing to the redo log. LGnn (Log Writer Worker) processes are not used when there is a SYNC standby destination. Possible processes include LG00-LG99.

Here is a list of new background processes in Oracle Database 12.1:
MOS Note 1625912.1 - New Background Processes In 12c 

For deep dive information about how to trace the LGWR (and DBWR) and the differences 11.2/12.1 and wait events and much more, please see this Deep Dive PDF from an UKOUG talk from Frits Hoogland.

Known Symptoms:


Solution:

Turn off multiple logwriters on IBM AIX at the moment - in some cases this may solve issues on other platforms as well but please don't take this as a generic recommendation for all platforms. We are seeing the issues mainly on IBM AIX.

Set in your spfile: 

_use_single_log_writer=true

.

--Mike 

Monday Nov 17, 2014

Oracle Database 12.1.0.2 EE for HP, AIX and zLinux available

Last week the remaining ports for Oracle Database 12c 12.1.0.2 became available at the usual sources:

Thursday Jan 09, 2014

Oracle Database 12c for AIX, HP-UX IA and zLinux now available

It took a while ... but finally Oracle Database 12c is available for:

Oracle Database 12c Release 1
Standard Edition, Standard Edition One, and Enterprise Edition

-Mike

About

Mike Dietrich - Oracle Mike Dietrich
Master Product Manager - Database Upgrade & Migrations - Oracle Corp

Based near Munich/Germany and spending plenty of time in airplanes to run either upgrade workshops or work onsite or remotely with reference customers. Acting as interlink between customers/partners and the Upgrade Development.

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