Re: Log switches every 4 minutes with 17MB Archivelogs despite 500MB log file size

Was it around every 15 minutes. Or 15 minutes. As I recall archive_lag_target either has a default of 15 minutes or often gets set like that.

On 3 Feb 2017 08:23, "Martin Decker" <martin.decker_at_ora-solutions.net> 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
>
>
>

--
http://www.freelists.org/webpage/oracle-l