Fedora 27 : About storage management and LVM.

About storage management offering flexibility like a complex task and LVM contributes to this complexity.
If you have seen incorrect usage of LVM many times and users are often neither aware of the possibilities or alternatives for the particular storage stacks.
If you use a VirtualBox software the you can increase the vdi file:

VBoxManage modifyhd fedora.vdi --resize 30960

About LVM
The wikipedia tell us:
In Linux, Logical Volume Manager is a device mapper target that provides logical volume management for the Linux kernel. Most modern Linux distributions are LVM-aware to the point of being able to have their root file systems on a logical volume.

To create a LVM, we need to run through the following steps:

• Select the physical storage devices for LVM 
• Create the Volume Group from Physical Volumes 
• Create Logical Volumes from Volume Group

All linux commands start in this case with lv and pv .
If you want to have a good management of storage then one most common task is :

The resize the PV (Physical Volume) with all free space.

All LVM commands start with lv so try to find all into your terminal by type lv ant then use keys TAB+TAB.
To resize the LVM use this commands:

$sudo su 
# pvs
  PV         VG              Fmt  Attr PSize   PFree
...
# lvdisplay
  --- Logical volume ---
  LV Path                /dev/fedora/root
  LV Name                
...
# lvextend -l+100%FREE /dev/fedora/root 
...
# df -Th

If you use Volume group on LVM then you need to use:

vgextend your_vg /dev/sda...