LVM

The Logical Volume Manager (LVM) provides means to dynamically organize partitions.

Basic Setup

LVM manages three types:

• physical volumes - directly on a physical partition
• volume groups - a group of physical volumes
• logical volumes

Create a logical volume

# formats the partion into a physical volume (check with pvdisplay)
pvcreate /dev/sda2
# creates a new volume group named pool (check with vgdisplay)
vgcreate pool /dev/sda2
# creates a new logical volume named "home" with the size of 10GB (check with lvdisplay)
# makes /dev/pool/home available
lvcreate -L 10G -n home pool
mkfs.ext4 /dev/pool/home

Use the Logical Volume

in your `configuration.nix`:

 filesystems."/home" = {
  "device": "/dev/pool/home";
  "fsType": "ext4";
}

Special LVM Modes

LVM provides a number of special features such as creating snapshots, raid for single Logical Volumes and much more. If you want to use these devices on bootup, the associated dm-* kernel module must be provided in the initrd (see for example #33646) . This is a non-exhaustive list of features and the corresponding kernel module to put into your

configuration.nix

:

boot.initrd.kernelModules = [
  "dm-snapshot" # when you are using snapshots
  "dm-raid" # e.g. when you are configuring raid1 via: `lvconvert -m1 /dev/pool/home`
];

Automated Partitioning

People have created a number of tools to automate the partitioning in NixOS:

NixOps

NixOps can repartition Hetzner Physical Machines, see [NixOps Manual].

Disko

Disko provides means to automatically generate the creation and configuration of logical volumes, see http://cgit.lassul.us/disko/tree/README.md .