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 --size 10G --name home pool
mkfs.ext4 /dev/pool/home
Use the Logical Volume
in your configuration.nix
:
fileSystems."/home" = {
device = "/dev/pool/home";
fsType = "ext4";
};
Booting with 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 and other options 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`
"dm-cache-default" # when using volumes set up with lvmcache
];
services.lvm.boot.thin.enable = true; # when using thin provisioning or caching
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 https://github.com/nix-community/disko