• Ubuntu Wiki: LVM … excellent overview of what LVM is, and what it can do

If a Logical Volume Manager name contains a dash, then the /dev/mapper/ version of that name will replace any single dash with a double dash.

As Example:
If the Logical Volume Group is some-volume-group & the Logical Volume is volume :

/dev/some-volume-group/volume
/dev/mapper/some--volume--group-volume

… are the 2 different ways in which that Logical Volume would exist in /dev .

This is why when I set names for a Logical Volume Group, and the Logical Volumes in that, I try to choose names that are short and to the point, made up of only letters and numbers.

• sudo blkid will show the UUID for both Drive Partitions and LVM Volumes.
• sudo fdisk -l will list any Drive Partitions that contain a “Linux LVM”.
  • This will also provide some low-level information about the size of LVM Volumes.
  • Expect a “doesn't contain a valid partition table” message for any LVM Volume.
• To List what an LVM Contains use sudo lvscan , sudo lvs or sudo lvdisplay
• The Graphical Utility, “GNOME Disks” (a.k.a. Disks) can also display information for Drive Partitions and LVM Volumes.

• Increase the size of an LVM logical volume then Increase the size of an ext2, ext3 or ext4 filesystem
• How do I shrink the root logical volume (LV) on LVM?
• Resizing a LVM swap volume

By default, installing Ubuntu will create a Swap Partition (/swap) that is the same size as the Physical Memory in the PC while Ubuntu is installing. Then the rest of the available drive space will be used for the Root Partition (/). When LVM has been used to install the operating system, it is possible to resize these partitions– to shrink the Root Partition by a few GB, then allocate that drive space to the Swap Partition.

Supposedly it is possible to expand an LVM Volume while it is in use. On the other hand, I expect that trying to shrink an LVM Volume while it is in use would amount to “just begging for trouble”. So in all cases, I try to “play it safe” by using Live Boot media when I want to resize anything.

• Live Boot to the Desktop using 12.04 LTS based media (USB / DVD / CD / etc.)
• From a Terminal Window use the following commands:

$ sudo apt-get update
$ sudo -i
# apt-get install lvm2
# lvscan

For a standard install of Ubuntu Studio 14.04, the results are as follows:
inactive '/dev/ubuntu-studio-vg/root' [xx.xxGiB] inherit
inactive '/dev/ubuntu-studio-vg/swap_1' [x.xxGB] inherit

The next command will first shrink the filesystem, then shrink the Logical Volume, which is the only safe method to do this.

# lvreduce --resizefs --size -2GB /dev/ubuntu-studio-vg/root
# lvexpand --size +2GB /dev/ubuntu-studio-vg/swap_1
# mkswap /dev/ubuntu-studio-vg/swap_1

The last command above remakes /swap – which permits it to use the full size of the larger Logical Volume.

#exit
$ sudo reboot