How to see hidden parameters in Oracle

To see hidden parameters in Oracle :

set echo off lines 149 pages 9999 feed off
clear col
clear break
clear compute
ttitle off
btitle off

COLUMN Param FORMAT a42 wrap head 'Underscore Parameter'
COLUMN Descr FORMAT a75 wrap head 'Description'
COLUMN SessionVal FORMAT a7 head 'Value|Session'
COLUMN InstanceVal FORMAT a7 head 'Value|Instnc'
ttitle skip 1 center 'All Underscore Parameters' skip 2

SELECT
a.ksppinm Param ,
b.ksppstvl SessionVal ,
c.ksppstvl InstanceVal,
a.ksppdesc Descr
FROM
x$ksppi a ,
x$ksppcv b ,
x$ksppsv c
WHERE
a.indx = b.indx AND
a.indx = c.indx AND
a.ksppinm LIKE '/_%' escape '/'
ORDER BY 1;

How to calibarte disk io using the RESOURCE_MANAGER package

@see :
resource manager io calibration in 11g
I/O Calibration Inside the Database

How to disable AUTO TASKS under Oracle 11g

Do the following commands :

set lines 180 pages 1000
 
BEGIN
  DBMS_AUTO_TASK_ADMIN.disable(
    client_name => 'auto space advisor',
    operation   => NULL,
    window_name => NULL);
END;
/
 
BEGIN
  DBMS_AUTO_TASK_ADMIN.disable(
    client_name => 'sql tuning advisor',
    operation   => NULL,
    window_name => NULL);
END;
/
 
BEGIN
  DBMS_AUTO_TASK_ADMIN.disable(
    client_name => 'auto optimizer stats collection',
    operation   => NULL,
    window_name => NULL);
END;
/

To see the auto task status, use the following command :

 
col client_name for a40
col attributes for a60

select client_name, status,attributes,service_name from dba_autotask_client;

CLIENT_NAME                              STATUS   ATTRIBUTES                                                   SERVICE_NAME
---------------------------------------- -------- ------------------------------------------------------------ ----------------------------------------------------------------
auto optimizer stats collection          DISABLED ON BY DEFAULT, VOLATILE, SAFE TO KILL
auto space advisor                       DISABLED ON BY DEFAULT, VOLATILE, SAFE TO KILL
sql tuning advisor                       DISABLED ONCE PER WINDOW, ON BY DEFAULT, VOLATILE, SAFE TO KILL