The danger of averages - Measuring I/O throughput
This query, based on AWR snapshots on sys.wrh$_sysstat, includes in its metrics the I/O read throughput for a given snapshot duration.
However it’s important to realise the huge limitation to this figure - it’s an average. It completely shoots you in the foot if you’re looking at capacity requirements.
Consider this real-life example extracted from the above query:
[sourcecode] Timestamp Total Read MBPS =========================================== 14-SEP-10 05.15.12.660 113.748 14-SEP-10 06.00.40.953 202.250 14-SEP-10 06.