Server has EFI partition on a separate storage device from the one containing /boot

This document (000019849) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12

Situation

During installation, the EFI boot partition was installed on on different storage device from the device containing /boot, or, some time after installation, changes were made which resulted in the filesystem containing /boot being on a different storage device from /boot/efi. For example:

NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda             253:0    0   20G  0 disk 
└─vda1          253:1    0  500M  0 part /boot/efi
vdb             253:16   0   20G  0 disk 
└─vdb1          253:17   0 19.5G  0 part 
  ├─system-swap 254:0    0  1.1G  0 lvm  [SWAP]
  ├─system-root 254:1    0 12.8G  0 lvm  /
  └─system-home 254:2    0  5.6G  0 lvm  /home

With the above configuration, unattended system boot fails, resulting in the process dropping to the grub shell prompt:

If the boot process is interrupted and then manual selection of the "sles-secureboot" option is made from the EFI firmware Boot Manager, then the system will boot fine. Also, using 'exit' at the grub prompt and manually selecting the default option of the EFI firmware boot menu should also allow the server to boot normally.

Resolution

The most likely reason behind this problem, is that the virtual machine is configured to boot from only one storage device (which is the default). Setting both storage devices (the device that contains /boot/efi and the device that contains /boot) as bootable, should fix the problem. Regarding boot device order, the device containing /boot/efi should come before the device containing /boot.

For a KVM virtual machine, the correct process to mark multiple drives as bootable is done using the following configuration applet:

Note that you may need to choose different storage devices from the ones in the graphic.

For virtual machines running under VMware, the solution is to add a line to the vmx configuration file listing both devices that contain /boot/efi and /boot:

e.g. bios.hddOrder = scsi0:0,scsi0:1

The above change should only be made whilst the VM is not running. You may also need to de-register and re-register the VM.

On other systems where the above is not possible, having /boot and /boot/efi on the same storage device is a way to overcome the issue, such as:

NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vda             253:0    0   20G  0 disk 
├─vda1          253:1    0  500M  0 part /boot/efi
└─vda2          253:2    0  500M  0 part /boot

Cause

Only one storage device is flagged as bootable. Therefore grub can only detect the device that contains /boot/efi and is unable to access the device that contains /boot. Therefore grub is unable to read grub.cfg to continue the boot process. This results in grub dropping to the emergency shell.

Additional Information

It is strongly recommended to keep the efi partition on the same storage device as /boot and the root filesystem.

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.