[Bug 985741] Re: multipath can't show device on which is setup lvm

[David Duffey]

Hi Vencent,

The initial ramdisk includes modules, configuration files, and scripts needed to boot
the system.  Since everything works post-boot, I suspect that some initialization
is the problem.

After looking through your information I am almost certain this is because during
the init process LVM is grabbing the block devices BEFORE multipath gets the chance.

Do you see that after the boot your volume groups are using scsi major numbers (8)
instead of multipath (252)?

It doesn't explain everything.. I would expect this to be a problem even for the
second partition, not only when you create an LVM on partition 1.  Nor does it
explain why the volume group doesn't come up, yet it found it's PVs (directly
instead of using the correct multipath).

Take a look at this bug report, it is a familiar problem. You might have to recreate
an initrd with the correct multipath and lvm config files, and also make sure the
kernel modules you need are loaded.

https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/246324

Sorry I do not have 11.10 installed or I would try to dig a bit deeper.  Canonical
does have a Technical Partner Program for vendors that want to have a formal
relationship (technical partner manager) to make their devices work well
out-of-the-box with Ubuntu.

David

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https://bugs.launchpad.net/bugs/985741

Title:
  multipath can't show device on which is setup lvm

Status in “multipath-tools” package in Ubuntu:
  Confirmed

Bug description:
  root at SGELLIN119:~# lsb_release -rd
  Description:    Ubuntu 11.10
  Release:        11.10

  affect package: multipath-tools, lvm2

  If  creating logical volume with Multipath on disk primary partition 1, multipath can’t find the 
  disks. Syslog show  such error when booting system

  kernel: [   27.604034] device-mapper: table: 252:5: multipath: error getting device
  kernel: [   27.604115] device-mapper: ioctl: error adding target to table

  
  I use fdisk to create two partitions on one physical lun.

  Mpath6:
  /dev/mapper/mpath6-part1
  /dev/mapper/mpath6-part2

  Mpath7:
  /dev/mapper/mpath7-part1
  /dev/mapper/mpath7-part2

  create a logical volume on  mpath6-part2, mpath7-part2
  Reboot  host, there is no exception and error logs. Multipath could
  Find all devices.

  root at SGELLIN119:~# multipath -ll | grep SYMM
  mpath9 (360000970000192602316533030453335) dm-10 EMC,SYMMETRIX
  mpath8 (360000970000192602316533030453334) dm-6 EMC,SYMMETRIX
  mpath7 (360000970000192602316533030453333) dm-7 EMC,SYMMETRIX
  mpath6 (360000970000192602316533030453332) dm-4 EMC,SYMMETRIX
  mpath5 (360000970000192602316533030453331) dm-3 EMC,SYMMETRIX

  
  root at SGELLIN119:~# lvs -v
      Finding all logical volumes
    LV      VG      #Seg Attr   LSize    Maj Min KMaj KMin Origin Snap%  Move Copy%  Log Convert LV UUID                       
    mlv     my_vg      1 -wi-a- 1020.00m  -1  -1 252  22                                         c3cECW-CJry-OdXI-O9bZ-lXq8-BUYq-obzcvB
    sym_lv2 sym_vg2    2 -wi-a-  200.00m  -1  -1 252  20                                         1t9SZa-QEEm-2u6p-lCqN-aqcd-xOpn-dC1YAu
    sym_lv3 sym_vg3    2 -wi-a-  200.00m  -1  -1 252  21                                         w4H00r-l71s-UURm-C32C-wDuS-fEF2-wlJFI0

  Then I use same way to create a lv on mpath6-part1 and mpath7-part1
  After rebooting host,  there are some error logs happen. 
  Multipath can’t find mpath6 and mapth7.  Of course the logical volums on
  Mpath6 and mpath7 were lost also.

  
  root at SGELLIN119:~# multipath -ll| grep SYMM
  mpath9 (360000970000192602316533030453335) dm-3 EMC,SYMMETRIX
  mpath8 (360000970000192602316533030453334) dm-2 EMC,SYMMETRIX
  mpath5 (360000970000192602316533030453331) dm-5 EMC,SYMMETRIX

  
  root at SGELLIN119:~# lvs -v
      Finding all logical volumes
    LV   VG    #Seg Attr   LSize    Maj Min KMaj KMin Origin Snap%  Move Copy%  Log Convert LV UUID                            
    mlv  my_vg    1 -wi-a- 1020.00m  -1  -1 252  1                                          c3cECW-CJry-OdXI-O9bZ-lXq8-BUYq-obzcvB

  
  the finding is that if creating lvm on disk primary partition 1.  Something were changed  and it lead multipath
  couldn’t find devices.

  root at SGELLIN119:~# udevadm info --query=all --name=/dev/mapper/mpath6
  P: /devices/virtual/block/dm-8
  N: dm-8
  L: -100
  S: mapper/mpath6
  S: disk/by-id/dm-name-mpath6
  S: disk/by-id/dm-uuid-mpath-360000970000192602316533030453332
  E: UDEV_LOG=3
  E: DEVPATH=/devices/virtual/block/dm-8
  E: MAJOR=252
  E: MINOR=8
  E: DEVNAME=/dev/dm-8
  E: DEVTYPE=disk
  E: SUBSYSTEM=block
  E: DM_NAME=mpath6
  E: DM_UUID=mpath-360000970000192602316533030453332
  E: DM_SUSPENDED=0
  E: DM_UDEV_RULES=1
  E: DEVLINKS=/dev/mapper/mpath6 /dev/disk/by-id/dm-name-mpath6 /dev/disk/by-id/dm-uuid-mpath-360000970000192602316533030453332

  Value "L" is negative compare to normal one

  Here is an temporary recovery way:
  4)	Service multipath-tools stop
  5)	Dmsetup remove_all
  6)	Service multipath-tools start
  However, the issue is consistent  after I reboot OS.

  If I remove lv  ( still have LVM package in OS) ,  multipath work
  well.

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