We are using a HP 230 Ultrium external tape drive to backup Informix data of 15 GB. While running the Informix command ontape -s -L 0, we get the error "Device does not support the blocksize. Archive failed -function open tape device \\tape0 failed code -1 errno -1". We have tried lowering the blocksize from 728 to 64. The backup works only at 64 but then takes hours to finish. Please help. Many thanks.