Hi, I have been implementing discard support for the various DM targets. I have a LUN that requires a 4K alignment for all discard requests. I forced the issue (by misconfiguring the alignment such that discards would be misaligned). Multipath failed the path once the SCSI layer got the following error. My question: shouldn't mpath _not_ fail the path for "Illegal Request".. "Parameter value invalid"? The same request would fail on any path given that the failure is on the target side (rejecting the malformed discard request). Following setup is ext4 FS ontop of linear DM mapping (dm-2) ontop of request-based mpath mapping (dm-1): EXT4-fs (dm-2): mounted filesystem with ordered data mode sd 3:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE sd 3:0:0:0: [sda] Sense Key : Illegal Request [current] Info fld=0x0 sd 3:0:0:0: [sda] Add. Sense: Parameter value invalid sd 3:0:0:0: [sda] CDB: Write same(16): 93 08 00 00 00 00 00 00 45 82 00 00 03 00 00 00 end_request: I/O error, dev sda, sector 17794 device-mapper: multipath: Failing path 8:0. end_request: I/O error, dev dm-1, sector 17794 end_request: I/O error, dev dm-1, sector 17794 end_request: I/O error, dev dm-1, sector 0 end_request: I/O error, dev dm-1, sector 386 quiet_error: 1228 callbacks suppressed Buffer I/O error on device dm-2, logical block 1 lost page write due to I/O error on dm-2 Buffer I/O error on device dm-2, logical block 2 lost page write due to I/O error on dm-2 end_request: I/O error, dev dm-1, sector 904 Buffer I/O error on device dm-2, logical block 260 lost page write due to I/O error on dm-2 end_request: I/O error, dev dm-1, sector 926 Buffer I/O error on device dm-2, logical block 271 lost page write due to I/O error on dm-2 end_request: I/O error, dev dm-1, sector 934 Buffer I/O error on device dm-2, logical block 275 lost page write due to I/O error on dm-2 end_request: I/O error, dev dm-1, sector 966 Buffer I/O error on device dm-2, logical block 291 lost page write due to I/O error on dm-2 Buffer I/O error on device dm-2, logical block 292 lost page write due to I/O error on dm-2 Here is the relevant scsi trace: kdmflush-3658 [000] 952692.258948: scsi_dispatch_cmd_start: host_no=3 channel=0 id=0 lun=0 data_sgl=1 prot_sgl=0 cmnd=(WRITE_SAME_16 lba=17794 txlen=768 protect=0 unmap=1 raw=93 08 00 00 00 00 00 00 45 82 00 00 03 00 00 00) <idle>-0 [000] 952692.259650: scsi_dispatch_cmd_done: host_no=3 channel=0 id=0 lun=0 data_sgl=1 prot_sgl=0 cmnd=(WRITE_SAME_16 lba=17794 txlen=768 protect=0 unmap=1 raw=93 08 00 00 00 00 00 00 45 82 00 00 03 00 00 00) result=(driver=DRIVER_OK host=DID_OK message=COMMAND_COMPLETE status=SAM_STAT_CHECK_CONDITION) multipathd-3661 [000] 952692.261484: scsi_dispatch_cmd_start: host_no=3 channel=0 id=0 lun=0 data_sgl=1 prot_sgl=0 cmnd=(READ_10 lba=0 txlen=8 protect=0 raw=28 00 00 00 00 00 00 00 08 00) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel