It is public knowledge that NFS is SLOW solution for Oracle in any way. Even though it is a supported option for Oracle RAC, it is VERY BAD idea, because of the over caching and the fact that Oracle will have to use the default system driver to send it commands and requests.

Thankfully, there is a solution for that called NFS Direct, which bypasses the default NFS driver and issues direct requests to the NFS. Direct NFS provides faster performance than what can be provided by the operating system's NFS driver as Oracle bypasses the operating system and generates exactly the requests it needs (no user configuration or tuning required). Data is cached just once in user space, which saves memory (no second copy in kernel space). Performance is further improved by load balancing across multiple network interfaces (if available).

Direct NFS is fairly easy to implement. Since it searched for the default location for NFS information: /etc/mtab /etc/fstab /etc/oranfstab

Oracle needs to find the NFS in at least one of these files. P.S. Bear in mind that the oranfstab has different configuration syntax than the usual /etc/fstab:

server: MyNFSserver1
path: 192.168.1.1
path: 192.168.1.2
export: /vol/oradata1 mount: /mnt/oradata1

To enable the Direct NFS after that is very easy:

cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk dnfs_on

cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk dnfs_off

After you have enabled the NFS, a message in the alert log should be displayed:

Oracle instance running with ODM: Oracle Direct NFS ODM Library Version 4.0