Disk IO_WAIT

SELECT  target_name, round(avg(average),2)
  FROM mgmt$metric_daily
WHERE     column_label = 'Total Disk I/O made across all disks (per second)'
    AND rollup_timestamp >= sysdate-14
    AND rollup_timestamp <= sysdate
group by target_name
order by 2 desc;

Up to 2000 is low (normal)
Between 2000-5000 is busy
over 5000 is high
over 10000 is extreme