Hi All,
We are looking for help to identify weird performance issue that we are facing on recently upgraded database, we were running 12c on windows 2012 OS , we migrated this database to 19c version on windows 2019 OS, Since then one of the application user complained the processing requests speed has reduced, the read/write to db has been reduced, when we look at the AWR report the highest event is showing as log file sync event , the average wait time 200ms , where as in 12c it was in micro seconds, we have verified that there are no DISK IO issues, our hardware is DELL Hyper converged disks and 200 plus other servers were running excellent performance, the impact is to only 19c servers, we see the log file sync latency only 19c servers ( this includes test machines also where there is no data load ) , we have done lot of tests to prove that disk is not a problem, we have compared sequential write test between 12c Vs 19c there is no difference , we have moved the redo log files to separate disk and we hardly have 4 log switches per day on average.
we have raised a ticket to oracle support they are of not much help, we have changed to filesystemio_options=NONE and Aynch and SETALL , none of them helped.
we also set "_use_adaptive_log_file_sync" to TRUE , we have not made any code changes to DB , there were no complains from users for past 12 years, the issue started only after 19c, Any help on this much appreacited