If you see the following error when trying to restore your Oracle backups (through RMAN):

ORA-27054: NFS file system where the file is created or resides is not mounted with correct options
Additional information: 2

the cause is possibly your are trying to restore your database to an NFS mount point which is not mounted correctly.

The following is for Solaris 10:

Change your /etc/vfstab entry

From:

Nfs_Host:/nfs/oracle – /oradata   nfs   –   yes   -

To:

Nfs_Host:/nfs/oracle – /oradata   nfs   –   yes   hard, bg,proto=tcp, vers=3, suid, rsize=32768, wsize=32768, intr,noac

Then, unmount and re-mount your volumes through /etc/vfstab