>>>We are running SUSE 8 Linux 2.4 kernel on Intel i 686 boxes >>>+ Netapp Filer + 9.2.0.6 RAC NFS mounted. >>> >>>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 -- //www.freelists.org/webpage/oracle-l