lvm cheatsheet

16 Mar 2019

There are certain technical things I keep forgetting no matter how many times I try them, ln usage, git parameters and the reason for this post, LVM. So, here goes a quick how-to for my future me.

Basics

In order to understand LVM it’s required to grasp its components.

Physical Volume (PV)

A PV is any block device that can be used as storage

Volume Group (VG)

A VG is a group of at least one PV, commonly contains many thought.

Logical Volume (LV)

A LV is a portion (partition) of a VG.

How to set up multiple hard drives as one volume?

Define /dev/sda, /dev/sdb2 and /dev/sdc3 as PVs

$ sudo pvcreate /dev/sda /dev/sdb2 /dev/sdc3

Create a Volume Group (VG) out of three just defined PVs

$ sudo vgcreate vg_name /dev/sda /dev/sdb2 /dev/sdc3

Create a Logical Volume (LV) out of the just defined VG

$ sudo lvcreate -l 100%FREE -n lv_name vg_name

Done!, now it can be formated and mounted as a normal HD, eg:

$ sudo mkfs.ext4 /dev/vg_name/lv_name
$ echo '/dev/vg_name/lv_name /mount_point ext4 defaults 0 0' | sudo tee -a /etc/fstab
$ sudo mount -a

How to mount a previously defined LVM volume

Recreate /dev/ LVM partitions

$ sudo vgchange -ay