SAME and OFA

Subject: SAME and OFA

As I read more and more about SAME (Strip And Mirror Everything) it occurs to me that the performance rationale for OFA is breaking down. Am I missing something here?

The most detailed paper I've read on SAME is "Optimal Storage Configuration Made Easy" by Juan Loaiza of Oracle.

As I understand it, OFA was developed with the idea that the Oracle server would have some number of discrete physical disks and various files would be placed on different physical disks in such a way as to minimize head/controller/channel contention. Further, OFA provided a proven and consistent strategy for placement of various files, given a certain number of physical drives.

Now, with SAME, the rational seems to be to group all of those physical drives into a large hardware controlled RAID array, and let the increased bandwidth and RAID controlled load balancing take care of it.

From our Day One on Oracle (running 7.3 on NT) we have been using RAID-1 and/or RAID-5 on our various Oracle servers and simulating an OFA architecture by chopping the RAID partitions up into multiple logical drives. I have been preaching (to no avail) to those who make the hardware purchase and configuration decisions that Oracle databases need more drives, not bigger drives.

If I'm not missing anything, my question is two-fold. First, has the ascendancy of large RAID arrays made OFA obsolete? Second, given an Oracle implementation on a RAID system, is there any rational for simulating OFA with multiple logical drives - or should we just develop a manageable directory structure on a single logical drive and quit worrying about OFA?

As I read over the above, it sounds like I'm an old fart that doesn't want to let go of old technology (OFA). The truth is that out of necessity, we've always had everything on either a single stripe set or a stripe set for data and a mirror set for rollbacks and archive logs. Further, when some poor sizing choices caused us to run out of space on some logical drives while barely utilizing others , we moved to replacing multiple logical drives (to simulate an OFA architecture) with multiple directories. So it seems that we have arrived at the essentials of SAME anyway. Should I enjoy being ahead of my time, or do I still have battles to fight? Is there anything I should be looking out for in the position I find myself in?

Comments and elucidation appreciated.

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Ed Stevens
(Opinions expressed do not necessarily represent those of my employer.)