Hi, multipath seems to work on gentoo, I have to load the modules in proper order, this is my configuration: cat /etc/conf.d/local.start # /etc/conf.d/local.start # This is a good place to load any misc programs # on startup ( use 1>&2 to hide output) /sbin/modprobe dm-emc /sbin/modprobe qla2300 /bin/sleep 5 /sbin/udevstart /etc/init.d/multipathd start is critical the command udevstart without only one path is seen, I experienced a kernel oops with kernel-2.6.12 (both vanilla-sources and gentoo-sources) when I load qla2300 module, here are the logs: Unable to handle kernel NULL pointer dereference at virtual address 00000000 printing eip: f8f262c8 *pde = 00000000 Oops: 0000 [#1] SMP Modules linked in: dm_round_robin qla2300 qla2xxx dm_emc dm_multipath dm_mod CPU: 1 EIP: 0060:[<f8f262c8>] Not tainted VLI EFLAGS: 00010086 (2.6.12-gentoo-r10) EIP is at rr_select_path+0x8/0x50 [dm_round_robin] eax: f30311cc ebx: 00000000 ecx: f7f4d08c edx: f30311cc esi: f46f1580 edi: 00000001 ebp: f46f1580 esp: f75f1ee0 ds: 007b es: 007b ss: 0068 Process kmpathd/1 (pid: 5836, threadinfo=f75f0000 task=c2171530) Stack: f30311c0 f8f12bf6 f30311cc f46f15b8 f46f1580 f7f4d080 f8f12cd9 f46f1580 f30311c0 f46f1580 f7f4d080 00000000 f46f158c f8f12fd9 f46f1580 00000001 c2171530 00000246 00000000 f46f1590 f46f15c8 f7f4d080 f46f15cc f46f1580 Call Trace: [<f8f12bf6>] __choose_path_in_pg+0x26/0x60 [dm_multipath] [<f8f12cd9>] __choose_pgpath+0xa9/0xc0 [dm_multipath] [<f8f12fd9>] process_queued_ios+0xd9/0x100 [dm_multipath] [<c012b229>] worker_thread+0x1b9/0x260 [<f8f12f00>] process_queued_ios+0x0/0x100 [dm_multipath] [<c01163c0>] default_wake_function+0x0/0x20 [<c01163c0>] default_wake_function+0x0/0x20 [<c012b070>] worker_thread+0x0/0x260 [<c012f85a>] kthread+0xba/0xc0 [<c012f7a0>] kthread+0x0/0xc0 [<c0101015>] kernel_thread_helper+0x5/0x10 Code: 40 08 8b 10 8b 48 04 89 11 89 4a 04 8b 13 89 42 04 89 10 89 58 04 89 03 31 c0 5b c3 8d b4 26 00 00 00 00 53 8b 44 24 08 8b 58 04 <8b> 03 39 d8 74 32 89 c1 8b 50 04 8b 00 85 c9 89 50 04 89 02 8b <4>device-mapper: dm-emc: long trespass command will be send device-mapper: dm-emc: honor reservation bit will not be set (default) Unable to handle kernel NULL pointer dereference at virtual address 00000000 printing eip: f8f262c8 *pde = 00000000 Oops: 0000 [#2] SMP Modules linked in: dm_round_robin qla2300 qla2xxx dm_emc dm_multipath dm_mod CPU: 0 EIP: 0060:[<f8f262c8>] Not tainted VLI EFLAGS: 00010086 (2.6.12-gentoo-r10) EIP is at rr_select_path+0x8/0x50 [dm_round_robin] eax: f748c8cc ebx: 00000000 ecx: f7f4d00c edx: f748c8cc esi: f46f1680 edi: 00000001 ebp: f46f1680 esp: f7517ee0 ds: 007b es: 007b ss: 0068 Process kmpathd/0 (pid: 5835, threadinfo=f7516000 task=f7f0e530) Stack: f748c8c0 f8f12bf6 f748c8cc f46f16b8 f46f1680 f7f4d000 f8f12cd9 f46f1680 f748c8c0 f46f1680 f7f4d000 00000000 f46f168c f8f12fd9 f46f1680 c200c558 f7f0e530 00000246 00000000 f46f1690 f46f16c8 f7f4d000 f46f16cc f46f1680 Call Trace: [<f8f12bf6>] __choose_path_in_pg+0x26/0x60 [dm_multipath] [<f8f12cd9>] __choose_pgpath+0xa9/0xc0 [dm_multipath] [<f8f12fd9>] process_queued_ios+0xd9/0x100 [dm_multipath] [<c012b229>] worker_thread+0x1b9/0x260 [<f8f12f00>] process_queued_ios+0x0/0x100 [dm_multipath] [<c01163c0>] default_wake_function+0x0/0x20 [<c01163c0>] default_wake_function+0x0/0x20 [<c012b070>] worker_thread+0x0/0x260 [<c012f85a>] kthread+0xba/0xc0 [<c012f7a0>] kthread+0x0/0xc0 [<c0101015>] kernel_thread_helper+0x5/0x10 Code: 40 08 8b 10 8b 48 04 89 11 89 4a 04 8b 13 89 42 04 89 10 89 58 04 89 03 31 c0 5b c3 8d b4 26 00 00 00 00 53 8b 44 24 08 8b 58 04 <8b> 03 39 d8 74 32 89 c1 8b 50 04 8b 00 85 c9 89 50 04 89 02 8b <4>device-mapper: dm-emc: long trespass command will be send device-mapper: dm-emc: honor reservation bit will not be set (default) Unable to handle kernel NULL pointer dereference at virtual address 00000000 printing eip: f8f262c8 *pde = 00000000 Oops: 0000 [#3] SMP Modules linked in: dm_round_robin qla2300 qla2xxx dm_emc dm_multipath dm_mod CPU: 2 EIP: 0060:[<f8f262c8>] Not tainted VLI EFLAGS: 00010086 (2.6.12-gentoo-r10) EIP is at rr_select_path+0x8/0x50 [dm_round_robin] eax: f7e4850c ebx: 00000000 ecx: f7f4d10c edx: f7e4850c esi: f46e4880 edi: 00000001 ebp: f46e4880 esp: f777dee0 ds: 007b es: 007b ss: 0068 Process kmpathd/2 (pid: 5837, threadinfo=f777c000 task=f7d11a40) Stack: f7e48500 f8f12bf6 f7e4850c f46e48b8 f46e4880 f7f4d100 f8f12cd9 f46e4880 f7e48500 f46e4880 f7f4d100 00000000 f46e488c f8f12fd9 f46e4880 c201c9d0 f7d11a40 00000246 00000000 f46e4890 f46e48c8 f7f4d100 f46e48cc f46e4880 Call Trace: [<f8f12bf6>] __choose_path_in_pg+0x26/0x60 [dm_multipath] [<f8f12cd9>] __choose_pgpath+0xa9/0xc0 [dm_multipath] [<f8f12fd9>] process_queued_ios+0xd9/0x100 [dm_multipath] [<c012b229>] worker_thread+0x1b9/0x260 [<f8f12f00>] process_queued_ios+0x0/0x100 [dm_multipath] [<c01163c0>] default_wake_function+0x0/0x20 [<c01163c0>] default_wake_function+0x0/0x20 [<c012b070>] worker_thread+0x0/0x260 [<c012f85a>] kthread+0xba/0xc0 [<c012f7a0>] kthread+0x0/0xc0 [<c0101015>] kernel_thread_helper+0x5/0x10 Code: 40 08 8b 10 8b 48 04 89 11 89 4a 04 8b 13 89 42 04 89 10 89 58 04 89 03 31 c0 5b c3 8d b4 26 00 00 00 00 53 8b 44 24 08 8b 58 04 <8b> 03 39 d8 74 32 89 c1 8b 50 04 8b 00 85 c9 89 50 04 89 02 8b <4>device-mapper: dm-emc: long trespass command will be sendhowever kernel-2.6.13 works fine (both vanilla and gentoo-sources) here are my multipath configuration grep -v "#" /etc/multipath.conf defaults { multipath_tool "/sbin/multipath -v0" udev_dir /dev polling_interval 10 default_selector "round-robin 0" default_getuid_callout "/sbin/scsi_id -g -u -s /block/%n" default_prio_callout "/bin/true" failback immediate } multipaths { multipath { wwid 3600601608c901200ccfe543f4053d911 alias 200Gb path_grouping_policy failover path_checker readsector0 path_selector "round-robin 0" failback immediate } multipath { wwid 3600601608c9012006269b8f63b87d911 alias 5Gb path_grouping_policy failover path_checker readsector0 path_selector "round-robin 0" failback immediate } multipath { wwid 3600601608c9012008ae5de2cc985d911 alias 300Gb path_grouping_policy failover path_checker readsector0 path_selector "round-robin 0" failback immediate } } The tests aren't very accurate because the machine is 100 Km away, tomorrow I'll do more accurate tests, I'll post results, big thanks to Cristophe for multipath-tools, big thanks to gistolero for his accurate testing on gentoo, your posts are very useful for me, any suggestions to improve my setup are welcome, I have to install naviagent? On redhat naviagent register powerpath name to cx 300, it works with multipath? Nicola P.S. for gistolero, I haven't your problem with multipathd (or so seems) however my hardware is different, I think also that the need to run udevstart is a gentoo bug, today gentoo has releases udev-0.68-r1 with start-stop script, if you read start script there is udevstart, however I haven't yet tested this script because they require unstable baselayout-1.12 |