The Oracle dNFS client passes the optimal record size to the ZFS Storage Appliance for each NFSv4 write request. The ZFS Storage Appliance NFSv4 server passes the record size to the ZFS file system with the I/O request. The ZFS file system then bypasses the default file system record size and uses the record size value passed with the I/O request. The record size can only be set for newly created files. If a file already exists the record size will not be changed.