Oracle Database Discussions

This question is regarding performance of an Oracle database running on an AIX 6.1 operating system with the volumes mounted using CIO option.

The CIO option refers to 'concurrent I/O', and is generally recommended by IBM for enhanced performance of database files that reside on volumes using the CIO option.

(NOTE: only the database files are placed on volumes mounted with CIO option. All other binary files, backups, etc., are placed on non-CIO mounted volumes.)

The reason this is questioned is because a simple write operation, such as copying a (large) file to a volume with CIO option takes forever. It takes an extraordinarily long time. My thinking is that IBM's recommendation to use CIO for volumes used for database data files is probably true for databases that are of high-read activity, but low write activity. I say this based on the very long time it takes to write a file to a volume that is mounted with the CIO option.

Also, in our world, our system admins and SAN storage admins have set everything up using RAID-05. All disk storage allocated to the database servers are RAID-05. But our volumes are literally striped across 300 to 400 disks, so any performance degradation that would normally be seen with RAID-05 would theoretically be negligible since the rebuilding the parity data distribution would be minimal across that many disks.

I'm very interested to know if anyone else has actually experienced this, and if there are exceptions for when to use CIO for database files as I suspect.

Thanks.

Edited by: ji li on Aug 24, 2009 6:43 AM

I posted this last week and hoped someone might be able to help out.
This is an important question that I could only answer by having 'spare' servers to do benchmark comparison testing, but unfortunately I don't. Any help or input would be appreciated.