Check if your database is using ASYNC_IO or not

TO check if your database is using async_io, just execute this query below;

SYS@ABR1 AS SYSDBA> select count(*) filetype_name,asynch_io from v$iostat_file group by filetype_name,asynch_io;

FILETYPE_NAME ASYNCH_IO
------------- ---------
   1 ASYNC_OFF
   1 ASYNC_OFF
   1 ASYNC_OFF
  15 ASYNC_ON
   1 ASYNC_OFF
   1 ASYNC_OFF
   1 ASYNC_OFF
   1 ASYNC_OFF
   1 ASYNC_OFF
   1 ASYNC_OFF
 185 ASYNC_ON
   1 ASYNC_OFF

12 rows selected.

SYS@ABR1 AS SYSDBA>


As you can see, I have 185 datafiles using ASYNC IO, if you cannot find anyone using ASYNC_ON, than you are not using ASYNC_IO, check your disk_asynch_io initialisation parameter and make sure it is set to TRUE.  Also check with your OS admin if your OS is ok to use ASYNC IO.

Best Regards,
Paulo Portugal