IO waits in SAP/Oracle

From: thuge <thuge_at_steelcase-strafor.com>
Date: Tue, 22 Jun 1999 13:04:44 GMT
Message-ID: <7ko1l5$894$1@nnrp1.deja.com>

Hello,

I have a "philosophical" problem about my SAP/Oracle/AIX database : I'm quite sure i have some IO waits problem :
- sar + vmstat give me about 50% of the time is spent in IO wait

iostat : mainly the most accessed disks are those which contains the Oracle data files.
Precise/SQL, SQL tuning tool, tells me that 95% of the SQL statements spent their time in IO wait

BUT the Oracle Buffer Cache Hit Ratio is always between 95% and 98%, that is to say Oracle finds more than 95% of the data in its buffer then there's no disk access. Am i wrong ?

The system is only for SAP/Oracle, the paging is low. Could someone explain this ???
Could these IO waits come from another thing than SAP/Oracle ?

Thanks for your help,

--
Thierry HUGE
AIX/Oracle/SAP Administrator
STEELCASE STRAFOR (FRANCE) Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't. Received on Tue Jun 22 1999 - 08:04:44 CDT