redo log average write time

[issamson]

hey all!
does anybody knows how can I calculate the average redo log
write time?

10x in advance.
Ido

[roobaron]

Look at stats on the database
(need timed_statistics = TRUE for meaningful stats)

A raw figure will be

redo write time / redo writes = avg. redo write time
This will be in writes/ 10s of millisec

The quickest log switch interval is something different

there is a script on http://www.ixora.com.au called
log_switch_interval.sql to determine this.

I suppose some extrapolation could be used to determine the average log switch interval

i.e redo size / redo write time = avg redo write speed
in bytes/10s of millisec

Then the average time will be the

redo log size / avg redo write speed

Have Fun

[pipo]

you can know that from v$log_history, doing something like :

select (a.first_time - b.first_time) * 3600 * 24
from v$log_history a, v$log_history b
where b.sequence#=a.sequence# - 1;

this will give you time in seconds for each redo logs. from there you can get min/max/avg times.