Unknown filesystem type ‘LVM2_member’

I went into safe mode at my home server, attempting to mount the root file system

:~$ sudo -i
[sudo] password for robert:
:~$ mkdir /mnt/tmp_root
:~$ mount /dev/sda1 /mnt/tmp_root
mount: unknown filesystem type 'LVM2_member'

The sda1 disk uses Logical Volume Mapping LVM. First of all, make sure LVM2 is available in your environment.

:~$ modprobe lvs
LV VG Attr LSize Origin Snap# Move Log Copy% Convert
LogVol00 lv_root -wi--- 72.44g
LogVol01 lv_root -wi---  1.97g
:~$ modprobe dm-mod

Now scan for physical volumes inside the LVM.

:~$ vgscan
Reading all physical volumes. This may take a while...
Found volume group "lv_root" using metadata type lvm2

Activate lv_root

:~$ vgchange -ay lv_root
2 logical volume(s) in volume group "lv_root" now active

Now the lv_root is mapped, so go ahead and mount it

:~$ mount /dev/lv_root/LogVol00 /mnt/tmp_root
:~$ ls /mnt/tmp_root