Hi Nigel Thanks everybody for the excellent advice. I understand that i would be better of thinking in terms of LUNS then disks and general rule of thumb would be one lun per spindle and one disk per lun (or equally sized disks that make up a lun) is this correct in plain english I also understand that for older data that is infrequently acessed i can mix and match disks and luns of different sizes and can have many luns per spindle where read write performance is not important. regards Hrishy -- //www.freelists.org/webpage/oracle-l