Minimum online access at present. Can't check MoS.
Sounds like an argument based on private redo threads, which aren't used in
RAC. But maybe reservation still happens- bit roughly 128K * transactions/ 10
(IIRC)
If it's only 17M of redo in 4 minutes, does it really matter or is this just
curiosity ?
Regards
Jonathan Lewis
(From my iPad mini; please excuse typos and auto-correct)
On 3 Feb 2017, at 08:21, Martin Decker <martin.decker@xxxxxxxxxxxxxxxxx>
wrote:
Dear Jonathan,
I apologize for the delay.
We have the majority of the workload on Instance 1. We saw switches with
15-18 MB archivelogs every 4 minutes on instance 1 and log switches with even
smaller archivelogs around every 15 minutes on instance 2. As the workload is
similar all the time, the behavior is visible all the time.
Support explained that it has to do with the "logfile space reservation
algorithm" (rough explanation in MOS 1356604.1) and with the fact that Redo
Buffer size is very similar compared to redo log size (both around 500M). We
are waiting for a more detailed explanation from support specifically for our
setup with #private strands, #cpus, log buffer, redo size. Next
recommendation was to reduce log buffer from 512m to 256m and reduce redo.
log file size to 700M.
Best regards,
Martin
