RE: RAC in NAS

 >>>We are running SUSE 8  Linux 2.4 kernel on Intel i 686 boxes 

>>>We think this gives us bad I/O performance with db file
>>>sequential reads as top waiting event, because the same
>>>queries in the database cloned on a non-RAC non-noac mounted
>>>NFS run much faster.

That is because without noac you are cached on the NFS client. Memory is faster than ethernet. But, you didn't quantify the wait event with a time measurement.

Be aware that "Intel I 686 **boxes**" (plural) have more I/O bandwidth than the filer. Crack open the filer and you'll see a little intel box (depending on model). So all I/O requests have to go over an northbridge chipset and out over PCI ethernet. A two node RAC cluster will always be able to swamp a single-headed filer. Single headed NAS
(filers) are a bottleneck. Measure sequential writes some time and you'll
see what I mean.

>>>Oracle blames Netapp and Netapp blames Oracle

Of course they do. That is Oracle standard procedure, and NetApp does it because they know large sequential I/O is the bane of a single headed filer--so they need an excuse.

More info:

http://h71028.www7.hp.com/enterprise/downloads/15650%20NAS%20Oracle%20WP %204A2.pdf

--
http://www.freelists.org/webpage/oracle-l