My Favorites

Close

Please to see your favorites.

  • Bookmark
  • Email Document
  • Printer Friendly
  • Favorite
  • Rating:

Troubleshooting boot issues (multipath with lvm).

This document (7022520) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 12

Situation

After update or upgrade of a system using multipath with logical volumes, the system doesn't boot normally anymore. Instead, it goes on emergency mode.

In the logs, messages similar to below can be observed :
# journalctl -b 1 -xl

Jan 08 13:55:41 sles12sp2-MPIO systemd[1]: Dependency failed for Local File Systems.

-- Subject: Unit local-fs.target has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit local-fs.target has failed.
--
-- The result is dependency.

Resolution

1 - Insert a SLES media which corresponds to the current running version on the system or the version . Then, set bios to boot primarily from the CD/iso inserted. On the menu, select “Rescue system” or “more” and “Rescue system”.

2 - By default, the rescue system will activate the LVM volume group right from the boot, which is not optimal when rescuing a system with multipath configured.

In order to deactivate the volume group, use the following command :
# vgchange -an

Now,  start the multipath service with :
# modprobe dm_multipath

For SLES 12 :
# systemctl restart multipathd

For SLES 11 :
# service multipathd restart
Confirm that the paths are visible with the command :
# multipath -ll

3 – Make sure that the filter on /etc/lvm/lvm.conf is set to reach the devices over multipath by changing the "filter =" line as described below :
filter = [ "a|/dev/disk/by-id/dm-uuid-.*mpath.*|", "r/.*/" ]

An alternative filter would be:

filter = [ "a|/dev/disk/by-id/dm-name.*|", "r/.*/" ]

Important: check which device links exist on the system!
After that, restart lvmetad with command:
# systemctl restart lvm2-lvmetad (SLES 12 only)
# pvscan ; vgscan
If set correctly, the “pvscan” command shouldn't output "Found duplicate PV" messages.

4 – Mount the root LV using the /dev/mapper and bind the /proc, /dev, /sys and /run to it:
# mount /dev/mapper/<rootvg>-<rootlv> /mnt

For SLES 12 :
# for i in dev proc sys run ; do mount -o bind /$i /mnt/$i ; done

For SLES 11 :
# for i in dev proc sys ; do mount -o bind /$i /mnt/$i ; done
after, change the root to /mnt :
# chroot /mnt

5 – Once in the chroot environment, make sure that the multipath is enabled again and that the paths are visible too :
For SLES12 :
# systemctl enable multipathd
# systemctl start multipathd

For SLES 11 :
# chkmod multipath on
# service multipathd start ;

# multipath -ll
6 – Make sure that local and multipathed devices are correctly listed on /etc/fstab.
For multipath devices, use "UUID=" or "/dev/disk/by-id/dm-name-*" instead of "/dev/sd*" or "/dev/disk/by-*", which should be used only for local disks.

7 – As we are still on the system activated by the chroot, change the /etc/lvm/lvm.conf and reload the lvmetad if necessary as described on step 3. Also make sure that there are  “Found duplicate PV” entries after running the “pvscan” command.

8 – Mount all volumes with “mount -a” command.
NOTE: In case /usr  is a separate filesystem, exit chroot here and mount it manually to /mnt/usr
# mount /dev/mapper/<rootvg>-<usrlv> /mnt/usr ; chroot /mnt ; mount -a

Make sure that all volumes were correct mounted and listed on “mount” or "findmnt" command.

It is also a good idea to verify if the output of “cat /proc/mounts” match with the “cat /etc/mtab”. If there are any differences between the two, please do as below :
# cat /proc/mounts > /etc/mtab
Note: this is not necessary on SLE12 !

9 - Make sure that the file /etc/dracut.conf.d/10-mp.conf has the line "force_drivers+="dm_multipath dm_service_time"" in it.

This can be added using the following command :
# echo 'force_drivers+="dm_multipath dm_service_time"' >> /etc/dracut.conf.d/10-mp.conf

NOTE: which modules to force depends on the path selector usage.
      while dm_multipath is a must have, dm_service_time can be replaced by dm_round_robin
      or dm_queue_length, depending on the system requirements.


10 – Next, make a backup of the old initrd and create a new one using the following commands :
# cd /boot
# mkdir brokeninitrd
# cp initrd-<version> brokeninitrd
For SLES 12 :
# dracut --kver <kernelnumber>-default -f -a multipath

For SLES 11 :
# mkinitrd -f multipath -k vmlinuz-<kernelnumber>-default -i initrd-<kernelnumber>-default

And also a new grub config  :
# yast bootloader

Once on the YaST interface, under “Bootloader Options” tab, change the value (by increasing or decreasing) on “Timeout in Seconds”.
This action will force the system to see the changes made and re-create the grub configuration. It is also a good idea to mark the “Boot from Master Boot Record” on “Boot Code Options” tab. 

After the changes, leave the YaST interface by selecting “ok”.

Alternatively, it is possible to manually make the changes as below :
# grub2-mkconfig -o /boot/grub2/grub.cfg
# grub2-install /dev/mapper/dm-name-... # choose the multipath device here!


11 - Ensure that the dm-multipath and lvm2 modules are included on the initrd image created previously with :
# lsinitrd /boot/init<version> |less

12 – Verify that the local devices are blacklisted in /etc/multipath.conf file. If this file doesn't exist, create one and insert a "blacklist" session.

Example below :

blacklist {

  wwid "3600508b1001030343841423043300400"

}

13 – Reboot the system.


Cause

- Bad entries in /etc/fstab.
- For some reason, the multipath or lvm modules were not included on the initrd image following a kernel update.
- Bad entry in /boot/grub2/device.map
-Bad entry in /etc/default/grub_installdevice
- Dependency failures on the modules included on the initrd image.

Additional Information

Additionally, it is also possible to manually check the init files in /boot in order to verify if there are missing dependencies or wrong entries. To do that, "mount" the initrd and modify it as described below :
# cd /boot
# mkdir brokeninitrd
# cp initrd-<version> brokeninitrd
# cd brokeninitrd
# xzcat /initrd-<version> |cpio -id


This will extract the initrd file, where the structure can be verified. On SLES 12 versions, every initrd file should have a link called "init" pointing  systemd at /usr/lib/systemd/systemd

Once the necessary changes are done, re-recreate the initrd file once again with :
# find . | cpio --create -c |xz -z --format=lzma >> ../initrd-<version>

Disclaimer

This Support Knowledgebase provides a valuable tool for NetIQ/Novell/SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7022520
  • Creation Date:05-JAN-18
  • Modified Date:19-NOV-19
    • SUSESUSE Linux Enterprise Server
< Back to Support Search

SUSE Support Forums

Get your questions answered by experienced Sys Ops or interact with other SUSE community experts.

Join Our Community

Support Resources

Learn how to get the most from the technical support you receive with your SUSE Subscription, Premium Support, Academic Program, or Partner Program.


SUSE Customer Support Quick Reference Guide SUSE Technical Support Handbook Update Advisories
Support FAQ

Open an Incident

Open an incident with SUSE Technical Support, manage your subscriptions, download patches, or manage user access.

Go to Customer Center