Public bug reported: As described by:
https://help.ubuntu.com/lts/serverguide/multipath-setting-up-dm- multipath.html The default value for failback is set to manual, instead of immediate. This effectively breaks the idea of multipath, which allows for upgrading E.G SAN A side, then upgrade B side when A is complete. With this set to manual, the system effectively halts. With a system containing 4 paths to a block device, you'll see this in logs during SAN firmware upgrade: November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-4/target0:0:3/0:0:3:0/block/sde and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-4/target0:0:3/0:0:3:0/block/sde and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:03.0/0000:08:00.0/host7/rport-7:0-1/target7:0:0/7:0:0:0/block/sdc and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda November 11th 2016, 13:58:05.000 4 kernel [585264.496735] sd 0:0:1:0: Asymmetric access state changed November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-scsi\x2d3600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:03.0/0000:08:00.0/host7/rport-7:0-1/target7:0:0/7:0:0:0/block/sdc and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:03.0/0000:08:00.0/host7/rport-7:0-1/target7:0:0/7:0:0:0/block/sdc and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda November 11th 2016, 13:58:05.000 3 systemd dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device: Dev dev-disk-by\x2did-wwn\x2d0x600a098038303731702b486638665456.device appeared twice with different sysfs paths /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:03.0/0000:08:00.0/host7/rport-7:0-1/target7:0:0/7:0:0:0/block/sdc and /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:07:00.0/host0/rport-0:0-2/target0:0:1/0:0:1:0/block/sda With the end result that the filesystem is no longer available. If the root partition is on a multipath device (SAN device), then /bin etc. are gone. Suggested fix: Set failback to immediate as default value This would ensure that what you would expect to happen, actually happens - which is when you upgrade SAN firmware, machines continue running like nothing happened due to redundant paths ** Affects: multipath-tools (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1641124 Title: Default failback value is badly chosen To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/1641124/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
