Christophe Varoqui wrote: > > Do failover device nodes get reassigned during the rescan ? > Like, for example, a configured path sda gets removed and a new path sdb > appears ? No, since I don't do a rescan on the bus but just on the target itself. When I had the controller in non-hubbed mode and did (when a controller has failed) "echo 1> /sys/class/scsi_host/host[1-2]/scan" I got two new devices, sde and sdf (I normally havesda,sdb,sdc and sdd) But if I instead did "echo 1 > /sys/class/scsi_device/[1-2]:0:0:0/device/rescan", I didn't get any new devices but the old ones start working again. Now, when I have the box in hubbed-mode, I can't seem to get new devices even when I do a scsi-host-scan, but just as before, a scsi-target-rescan will get my devices back to order again. Also, I've noticed that it's not only when a controller fails that this happens, when a failed controller is "revived" the same thing might happen. As far as I've been able to tell, the more I/O-transactions at the time of the failure, the more likely that the (SCSI) device will be marked as "dead". If I do "while /bin/true ;do dd if=/dev/zero of=/mnt/test count=20000; sleep 1" and fail (or revive) a controller it seems to work in 50% of the cases, with 2 sec sleep there is rarely any problem but with no sleep at all it fails nearly 100% of the times And in all types of tests, if I do a SCSI-target(path) rescan before multipath decides both paths are dead, both paths will work again and the multipath-device will never fail. > If so, the FC transport class is in charge of the timeout triggering the > dead devices removal. > A hardware handler wouldn't help here. > > Can you paste a before/after scsi rescan "multipath -l" output ? > They are identical [root@asl005 ~]# multipath -l mpath1 (3600d0230000000000b01910b4d313400) [size=97 GB][features=0][hwhandler=0] \_ round-robin 0 [prio=0][active] \_ 1:0:0:0 sdb 8:16 [active][undef] \_ 2:0:0:0 sdc 8:32 [active][undef] [root@asl005 ~]# dmesg |tail -20 SCSI error : <1 0 0 0> return code = 0x20008 end_request: I/O error, dev sdb, sector 21247352 end_request: I/O error, dev sdb, sector 21247360 SCSI error : <1 0 0 0> return code = 0x20008 end_request: I/O error, dev sdb, sector 21036576 end_request: I/O error, dev sdb, sector 21036584 Aborting journal on device dm-5. ext3_abort called. EXT3-fs error (device dm-5): ext3_journal_start_sb: Detected aborted journal Remounting filesystem read-only EXT3-fs error (device dm-5) in start_transaction: Journal has aborted __journal_remove_journal_head: freeing b_committed_data printk: 254766 messages suppressed. Buffer I/O error on device dm-5, logical block 2092209 lost page write due to I/O error on dm-5 Buffer I/O error on device dm-5, logical block 2093234 lost page write due to I/O error on dm-5 printk: 485 messages suppressed. Buffer I/O error on device dm-5, logical block 1 lost page write due to I/O error on dm-5 [root@asl005 ~]# multipath -l mpath1 (3600d0230000000000b01910b4d313400) [size=97 GB][features=0][hwhandler=0] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:0 sdb 8:16 [failed][undef] \_ 2:0:0:0 sdc 8:32 [failed][undef] [root@asl005 ~]# echo 1 > /sys/class/fc_transport/target1\:0\:0/device/1\:0\:0\:0/rescan [root@asl005 ~]# multipath -l mpath1 (3600d0230000000000b01910b4d313400) [size=97 GB][features=0][hwhandler=0] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:0 sdb 8:16 [failed][undef] \_ 2:0:0:0 sdc 8:32 [failed][undef] [root@asl005 ~]# multipath [root@asl005 ~]# multipath -ll mpath1 (3600d0230000000000b01910b4d313400) [size=97 GB][features=0][hwhandler=0] \_ round-robin 0 [prio=0][active] \_ 1:0:0:0 sdb 8:16 [active][undef] \_ 2:0:0:0 sdc 8:32 [active][undef] -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
