As far as I know "redo size" is the sum of the redo byte written to the log
buffer by the invidivual sessions.
The log writer reports redo blocks written, and the difference between redo
size and redo blocks written (typically 512 byte blocks - though 4K is now
possible) is reported as the "redo wastage";
Then, I think, the "redo block written" is "logical" blocks, not physical
blocks, i.e. I don't think it would be multiplied by 3 if you had 3 files
per log group - consequently I don't THINK writes to remote log files would
show up in these older statistics.
Regards
Jonathan Lewis
On Thu, Apr 23, 2020 at 5:00 PM Tim Gorman <tim.evdbt@xxxxxxxxx> wrote:
Mightn't "redo size" be affected by the number of log archive destinations?
If the standby is MAX PROTECTION or MAX AVAILABILITY , then LGWR
process(es) have to write out to the standby along with writes down to the
online redo log files.
I can't imagine any process other than LGWR to calculate and store the
"redo size" statistic, so my question is whether LGWR tallies bytes read
from the Log Buffer, or whether it tallies bytes written to the
destinations (i.e. online redo plus MAX PROT/AVAIL standby dests)?
