Mount logical volumes (LVM) partition from external Disk

According to OS and configuration, volume may not be automatically activated (e.g. if you have just plugged it in).
In such case, you can
begin activating the volume, and only then mounting it.

This is an easy solution to solve that.

 - before all, you can use the following command to list volumes, and there activate status
lvscan

 - list physical volumes
pvs

 - once you get the name of the volume you want, activate it
vgchange -a y "NAME"

 - list its logical volumes
lvdisplay "NAME"

 - you can now mount this volume
mount "LV_PATH" "MOUNT POINT"

You can now read/write data on external volume.

Once you don't need anymore this access, to properly reverse that :
 - umount the volume
umount "MOUNT POINT"

 - unactivate the volume
vgchange -a n "NAME"

 - ensure all is OK
lvscan

You can now unplug external disk.