Oracle Performance: Showing Redo Generation for RAC

Sometimes I need to quantify the amount of redo being generated over a period of time. For example, if one uses replication, such as Golden Gate, it is important to know how much data is being replicated.

Here is a simple way to sum-up all redo for all RAC nodes. I only list periods where there has been substantial activity. I also show the begin time of the snapshot, for easy reference:

select s.snap_id,
to_char(begin_interval_time, 'dd-mon-yy-hh24:mi') BEG,
round(sum(average*3600/1000000000)) TOT_REDO_GB
from dba_hist_snapshot s, DBA_HIST_SYSMETRIC_SUMMARY M
where s.snap_id = m.snap_id
and s.snap_id between 1480 and 1650
and s.instance_number = m.instance_number
and metric_name like 'Redo Generated Per Sec%'
and Round(average/99999) > 100
group by s.snap_id, to_char(begin_interval_time, 'dd-mon-yy-hh24:mi');

SNAP_ID BEG TOT_REDO_GB
--------- --------------- -----------
1491 08-oct-19-13:00 85
1492 08-oct-19-14:00 45
1493 08-oct-19-15:00 116
1495 08-oct-19-17:00 124
1496 08-oct-19-18:00 38
1502 09-oct-19-00:00 55
1523 09-oct-19-21:00 113
1526 10-oct-19-00:00 55
1533 10-oct-19-07:00 137
1549 10-oct-19-23:00 68
1550 11-oct-19-00:00 54
1559 11-oct-19-09:00 127
1565 11-oct-19-15:00 1207
1566 11-oct-19-16:00 1265
1567 11-oct-19-17:00 1433
1568 11-oct-19-18:00 542
1574 12-oct-19-00:00 55
1598 13-oct-19-00:00 55
1622 14-oct-19-00:00 43
1642 14-oct-19-20:00 136
1646 15-oct-19-00:00 43

Naturally, you can customize the script for the period of interest.