what about MO? (magneto-optic disks) - WORM (write once, read many) - WMRM (write many, read many) and what about magnetic-tapes? (e.g. DDS4, DLT, LTO2) which of them lasts for the most? MO units and disks are a bit costly say >=50 euro for 4.5Gbyte R/W cartridge and say >=500 euro for the driver unit (SCSI)