SLES12 exits to emergency shell with active LVM snapshots during reboot

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Environment

SUSE Linux Enterprise Server 12

Situation

The system exits into emergency shell after rebooting not being able to access LVM snapshot(s):

[...]
[ OK ] Found device /dev/mapper/system-swap.
[ OK ] Started Show Plymouth Boot Screen.
[ OK ] Reached target Paths.
[ OK ] Reached target Basic System.
[ OK ] Found device /dev/mapper/system-swap.
Starting Dracut Emergency Shell...
Warning: /dev/disk/by-uuid/6cbf0ef6-8120-4bca-9bba-bd6ed383728b does not exist
Warning: /dev/system/root does not exist

Running rdsosreport shows the dm_snapshot module is not available in the initrd.

Resolution

Before issuing the reboot command make sure dm_snapshot is listed in lsmod output and run

dracut -f

to rebuild the initrd and include the missing dm_snapshot module. The required fix is already contained in dracut-037-34.4 which is shipped with SLES12.

Cause

The initrd built during installation is missing the dm_snapshot module.

Disclaimer

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