Re: the argument with OFA and RAID

IMO,
The only thing that really counts is the distribution of I/O amongst PHYSICAL!!! disks, as shown by the results of the iostat command. You could have a perfect OFA configuration laid out on different filesystems! as recommended, all on a single physical disk and it would help you NOTHING.
That is, your disk is overflooded with requests and it can't handle the number of requests and the disk I/O queue is permanently non-zero. 20 physical disks referred to as 1 logical disk by the O/S would put you at the mercy of RAID to distribute the files amongst physical disks, and you wouldn't be able to influence it. I would probably end-up in a severe argument with your colleague.
IMO, the goal of OFA is twofold:
- to make your setup transparent, so you wouldn't end up with files of
multiple instances in one single directory structure
- to make a 'reasonable' distribution of files amongst filesystems, which
for me refers to physical disks.

Hth,

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Sybrand Bakker, Oracle DBA Received on Thu Oct 07 1999 - 23:38:31 CDT