Nigel Noble's Oracle Blog

08/01/2015

“log file sync” and the MTTR Advisor

Filed under: 11gR2, Performance — Nigel Noble @ 6:12 pm

I recently investigated a performance problem on an Oracle 11.2 OLTP trading system and although we still don’t fully understand the issue (and which versions of Oracle it effects), I thought I would share what we found (and how we found it). We had a hardware failure on the database server, within 30 seconds the database had automatically been restarted on an idle identical member of the cluster and the application continued on the new database host. A few days later I just happened to notice the following change in the LGWR trace file. I noticed that the Log Writer trace was showing more “kcrfw_update_adaptive_sync_mode” messages than normal.

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