Dear,

we've got some performance problems and came up with the following:

drop table previous_events;

CREATE TABLE previous_events AS
SELECT SYSDATE timestamp, v$system_event.*
FROM v$system_event;

SELECT A.event,
A.total_waits - NVL (B.total_waits, 0) total_waits,
A.time_waited - NVL (B.time_waited, 0) time_waited
FROM v$system_event A, previous_events B
WHERE B.event (+) = A.event
AND A.event NOT IN
(
'client message', 'dispatcher timer', 'gcs for action',
'gcs remote message', 'ges remote message',
'lock manager wait for remote message',
'null event', 'Null event', 'parallel query dequeue', 'pipe get',
'PL/SQL lock timer', 'pmon timer', 'PX Deq Credit: need buffer',
'PX Deq Credit: send blkd', 'PX Deq: Execute Reply',
'PX Deq: Execution Msg', 'PX Deq: Signal ACK',
'PX Deq: Table Q Normal', 'PX Deque Wait', 'PX Idle Wait',
'queue messages', 'rdbms ipc message',
'smon timer', 'SQL*Net message to client',
'SQL*Net message from client', 'SQL*Net more data from client',
'virtual circuit status', 'wakeup time manager'
)
ORDER BY time_waited desc;





EVENT TOTAL_WAITS TIME_WAITED
i/o slave wait 1059 6737
db file sequential read 1872 1445
db file scattered read 4081 1040

The create statement and the select are run within one minute. It seems our I/O slave is very high. Could someone tell me where to look for this?

Thx,

Rik