random things

Although the format /dev/[vg_name]/[lv_name] format is easier to read when you got plenty of VGs (compared to /dev/mapper/[vg_name]-[lv_name]), it won’t work at boot.

This is the few lines of default initramfs script which is responsible for the behaviour described above:
/usr/share/initramfs-tools/scripts/local-top, from line 40:

# Make sure that we have a d-m path
vg=${vg#/dev/mapper/}
if [ "$vg" = "$1" ]; [...]