FWIW, I'm running LVM on top of device mapper to HSV110s, and it seems to work. This is my multipath.conf devices { device { vendor "COMPAQ " product "HSV110 (C)COMPAQ" path_selector "round-robin 0" path_grouping_policy "group_by_serial" getuid_callout "/sbin/scsi_id -g -u -s /block/%n" path_checker "readsector 0" #path_checker "tur" #features "1 queue_if_no_path" } } You might want to try the "readsector 0" checker rather than the test-unit-ready one. As others have pointed out, if you are running the qlogic driver then setting #define QL_DEBUG_LEVEL_2 in drivers/scsi/qla2xxx/qla_dbg.h makes the driver print out some more useful scsi information. Guy -- Dr. Guy Coates, Informatics System Group The Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK Tel: +44 (0)1223 834244 ex 7199