I used this only last week - found at http://orafaq.com/usenet/comp.databases.oracle.server/2007/07/12/0854.ra w [ first flush the buffer cache ] sys@xxxxxxxxx> alter system flush buffer_cache; System altered. [ Then issue (as user oracle) ] oracle@ironman:~$ truss -f -t open,ioctl -u ':directio' sqlplus user/ pass ... (lots of output here) [ Then type ] create table a as select * from big_table; You will see that for every data file opened, directio is explicitly turned off: 24399: open("/u04/oradata/BIA/APM_DATA13.dbf", O_RDWR|O_DSYNC) = 11 24399: -> libc:directio(0x10f, 0x0, 0x1, 0x0) 24399: ioctl(271, 0x2000664C, 0x00000000) = 0 The 3rd parameter to the ioctl() call is 0 for directio_off, and 1 for directio_on. ________________________________ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of DBA Deepak Sent: 17 October 2007 11:21 To: oracle-l Subject: filesystemio_options option on solaris 9 sparc 64-bit (Oracle 10g) Hi Experts, Have enabled directIO on Solaris 9 (Oracle 10g) by setting the parameter filesystemio_options=setall Is there any way that I can verify whether Oracle is using directIO or not? -- Regards, Deepak Oracle DBA BJSS Limited, 1st Floor Coronet House, Queen Street, Leeds LS1 2TW. Registered in England with company number 2777575. http://www.bjss.co.uk