Hello, i try to setup a multipath to a EMC Clariion Device with the following infrstructure. Kernel 2.6.10-rc3 and udm2 Patch. multipath-tools 0.4.1 I have one qla2310 Adapter "Firmware version 3.03.02 IPX, Driver version 8.00.00b21-k" wich is zoned to SPA Port0 and SPB Port0 of the Clariion. So we have two path to the LUN. I setup multipath.conf with the following. multipath { wwid 3600601601b121200540b8c1caf4ad911 alias yellow path_grouping_policy failover path_checker emc_clariion path_selector "round-robin 0" getuid_callout "/sbin/scsi_id -g -u -s %n" } device { vendor "DGC " product "RAID 5 " path_grouping_policy failover getuid_callout "/sbin/scsi_id -g -u -s /block/%n" path_checker emc_clariion } When i start the multipathd i get the following table yellow: 0 20971520 multipath 0 0 2 1 round-robin 0 1 1 8:64 1000 round-robin 0 1 1 8:80 1000 multipath -v2 -l reports yellow (3600601601b121200540b8c1caf4ad911) [size=10 GB][features="0"][hwhandler="0"] \_ round-robin 0 [enabled][first] \_ 2:0:1:0 sde 8:64 [ready ][active] \_ round-robin 0 [enabled] \_ 2:0:2:0 sdf 8:80 [ready ][active] I can work with the device dd if=/dev/yellow of=/dev/null count=1000 When i disable one port on the switch to the Clarion, or unplug the cable from the SP (Clariion) the dd command goes to D+ state (ps ax) and I get messages like this. Dec 23 14:35:31 lxssantm1 kernel: SCSI error : <2 0 1 0> return code = 0x20000 Dec 23 14:35:31 lxssantm1 kernel: end_request: I/O error, dev sde, sector 0 Dec 23 14:35:31 lxssantm1 kernel: end_request: I/O error, dev sde, sector 8 Dec 23 14:35:31 lxssantm1 multipathd: devmap event on yellow Dec 23 14:35:45 lxssantm1 multipathd: 8:64 : emc_clariion_checker: query command indicates error Dec 23 14:35:45 lxssantm1 kernel: SCSI error : <2 0 1 0> return code = 0x10000 Dec 23 14:35:45 lxssantm1 last message repeated 6 times Dec 23 14:35:45 lxssantm1 kernel: device-mapper: multipath_message received. argc: 2 Dec 23 14:35:45 lxssantm1 kernel: Unable to handle kernel paging request at virtual address f8d44080 Dec 23 14:35:45 lxssantm1 kernel: printing eip: Dec 23 14:35:45 lxssantm1 kernel: f8f47e43 Dec 23 14:35:45 lxssantm1 kernel: *pde = 1fc86067 Dec 23 14:35:45 lxssantm1 kernel: Oops: 0000 [#1] Dec 23 14:35:45 lxssantm1 kernel: SMP Dec 23 14:35:45 lxssantm1 kernel: Modules linked in: dm_round_robin dm_multipath joydev st sr_mod ide_cd cdrom nvram edd speedstep_lib fre q_table processor ipv6 sg intel_agp agpgart i2c_piix4 i2c_core evdev tulip dm_mod reiserfs qla2300 qla2xxx scsi_transport_fc gdth aic7xxx sd_mod scsi_mod Dec 23 14:35:45 lxssantm1 kernel: CPU: 0 Dec 23 14:35:45 lxssantm1 kernel: EIP: 0060:[<f8f47e43>] Not tainted VLI Dec 23 14:35:45 lxssantm1 kernel: EFLAGS: 00010247 (2.6.10-rc3) Dec 23 14:35:45 lxssantm1 kernel: EIP is at trigger_event+0x3/0x10 [dm_multipath] Dec 23 14:35:45 lxssantm1 kernel: eax: f8d44080 ebx: f31787ec ecx: dfe30000 edx: 00000216 Dec 23 14:35:45 lxssantm1 kernel: esi: dfe30000 edi: f31787f0 ebp: f3178760 esp: dfe33f60 Dec 23 14:35:45 lxssantm1 multipathd: event checker startup : yellow Dec 23 14:35:45 lxssantm1 kernel: ds: 007b es: 007b ss: 0068 Dec 23 14:35:45 lxssantm1 kernel: Process events/0 (pid: 6, threadinfo=dfe32000 task=dffefa60) Dec 23 14:35:45 lxssantm1 kernel: Stack: c0128a38 dfe30020 f8f47e40 00000216 dfe32000 dfe3000c ffffffff ffffffff Dec 23 14:35:45 lxssantm1 kernel: 00000001 00000000 c0116330 00010000 00000000 c18109c0 c1810060 00000000 Dec 23 14:35:45 lxssantm1 kernel: 00000000 dffefa60 c0116330 00100100 00200200 dffefbc4 00000000 00000000 Dec 23 14:35:45 lxssantm1 kernel: Call Trace: Dec 23 14:35:45 lxssantm1 kernel: [<c0128a38>] worker_thread+0x1a8/0x230 Dec 23 14:35:45 lxssantm1 kernel: [<f8f47e40>] trigger_event+0x0/0x10 [dm_multipath] Dec 23 14:35:45 lxssantm1 kernel: [<c0116330>] default_wake_function+0x0/0x10 Dec 23 14:35:45 lxssantm1 kernel: [<c0116330>] default_wake_function+0x0/0x10 Dec 23 14:35:45 lxssantm1 kernel: [<c0128890>] worker_thread+0x0/0x230 Dec 23 14:35:45 lxssantm1 kernel: [<c012c666>] kthread+0x86/0xb0 Dec 23 14:35:45 lxssantm1 kernel: [<c012c5e0>] kthread+0x0/0xb0 Dec 23 14:35:45 lxssantm1 kernel: [<c01019b5>] kernel_thread_helper+0x5/0x10 Dec 23 14:35:45 lxssantm1 kernel: Code: 89 f0 e8 61 fc ff ff 8b 7e 38 85 ff 75 96 8b 46 28 85 c0 74 96 8b 5e 2c 85 db 75 8f c7 44 24 04 01 00 00 00 eb 85 89 f6 8b 40 08 <8b> 00 e9 76 e8 d4 ff 8d b6 00 00 00 00 56 85 d2 53 89 ce 89 c3 Dec 23 14:35:56 lxssantm1 multipathd: 8:64 : emc_clariion_checker: Path healthy Enable the Switch Port or plugging the cable has no effect. The device /dev/yellow remains dead. No failover !!!!