grub2 can't find lvmid device when a 2nd disk is added to the root volume group

This document (7024181) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12  for POWER including all Service Packs
SUSE Linux Enterprise Server 15  for POWER including all Service Packs

Situation

The root volume (LVM) is running out of space and needs to be extended.
To achieve that another physical volume (pv) is created and added to the volume group containing /
After that, the root volume is extended (lvextend), subsequently the filesystem of / is extended as well
After rebooting the system, grub2 can't find the root volume anymore and is stuck with an errormessage similar to:
 
error: disk 'lvmid/eBY8sJ-l5YB-nVGq-dhld-lbDa-hQxT-P8eXl9/zbpPOS-yUU1-pgTr-QLJC-5jeK-d3ts-gNwtzw' not found.
 

 
 

Resolution

To make the system reboot reliably the bootloader must be installed on every disk/physical volume in the root volume group.
 
To be able to install the bootloader it is mandatory to use partitions. raw disks, formatted as physical volumes (LVM), do not have a reserved space for the bootloader and installation may fail. 
 
Assuming the system consists of a singe LUN /dev/mapper/360000000000000000000000000000000, holding two partitions of which the first is PReP and the second partition is a physical volume for /dev/system/root
The correct workflow would be:
 
  • Assign another LUN to the system (e.g. dev/mapper/360000000000000000000000000000010)
  • Create a GPT partition table. (IMPORTANT! Msdos partition table does not work!)
  • create a PReP partition of about 8MB size /dev/mapper/360000000000000000000000000000010-part1
  • create a second partition consuming all free space on the LUN e.g. /dev/mapper/360000000000000000000000000000010-part2
  • pvcreate /dev/mapper/360000000000000000000000000000010-part2
  • vgextend system  /dev/mapper/360000000000000000000000000000010-part2
  • lvextend -L+20G /dev/system/root
  • btrfs filesystem resize max /
Now the root volume is extended, as well as the root FS.
Now install the bootloader on BOTH PReP partitions
  • grub2-install /dev/mapper/360000000000000000000000000000000-part1
  • grub2-install /dev/mapper/360000000000000000000000000000010-part1
 
repeat that until all PVs in the root volumegroup are covered.

Cause

NOTE: This issue is only seen on POWER, other architectures are not affected as it's caused by an issue in OpenFirmware.
 
Whenever there is more than one disk/LUN in the LVM volumegroup Openfirmware cannot find the bootloader so there must a PReP partition on each LUN and the bootloader needs to be installed (or refreshed in case of any changes) on all disks/LUNS.
At the time this TID was written, this needed to be done manually.

Additional Information

Ideally the above is done before the system stops booting.
In case it's too late already follow the steps in TID 7022520 - Troubleshooting boot issues (multipath with lvm)
to boot a rescue system, configure lvm on multipath and finish with the grub2-install commands before rebooting again
 

Disclaimer

This Support Knowledgebase provides a valuable tool for 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:7024181
  • Creation Date: 15-Oct-2019
  • Modified Date:23-Feb-2021
    • SUSE Linux Enterprise Server

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