Install Arch Linux on LVM

You should create your LVM Volumes between the partitioning and formatting steps of the installation procedure. Instead of directly formatting a partition to be your root file system, the file system will be created inside a logical volume (LV).

Quick overview:

• Install the required packages. (refer to LVM#Getting started)
• Create partition(s) where your physical volumes (PVs) will reside.
• Create your PVs. If you have one disk it is best to just create one PV in one large partition. If you have multiple disks you can create partitions on each of them and create a PV on each partition.
• Create your volume group (VG) and add all PVs to it.
• Create logical volumes (LVs) inside that VG.
• Continue with Installation guide#Format the partitions.
• When you reach the “Create initial ramdisk environment” step in the Installation guide, add the lvm2 hook to /etc/mkinitcpio.conf (see below for details).

Warning: /boot cannot reside in LVM when using a boot loader which does not support LVM; you must create a separate /boot partition and format it directly. While this partition is already necessary for UEFI/GPT it is an additional partition for both BIOS/MBR and BIOS/GPT. Create the partition /boot for BIOS systems irrespective of the partition table and create a Linux filesystem on it (partition type 8300 in gdisk). Mount the created partition to /boot. Only GRUB is known to support LVM. Nevertheless, it requires this separate boot partition.

Installation

You will follow along with the installation guide until you come to Installation guide#Partition the disks. At this point you will diverge and doing all your partitioning with LVM in mind.

Create partitions

First, partition your disks as required before configuring LVM.

Create the partitions:

• If you use Master Boot Record partition table, set the partition type ID to 8e (partition type Linux LVM in fdisk).
• If you use GUID Partition Table, set the partition type GUID to (partition type Linux LVM in fdisk and in gdisk).

Create physical volumes

To list all your devices capable of being used as a physical volume:

# lvmdiskscan

Create a physical volume on them:

# pvcreate DEVICE

This command creates a header on each device so it can be used for LVM. As defined in LVM#LVM building blocks, DEVICE can be any block device, e.g. a disk , a partition /dev/sda2 or a loop back device. For example:

# pvcreate /dev/sda2

You can track created physical volumes with:

# pvdisplay

You can also get summary information on physical volumes with:

# pvscan

Note: If using a SSD without partitioning it first, use pvcreate --dataalignment 1m /dev/sda (for erase block size < 1 MiB), see e.g. here

Create and extend your volume group

First you need to create a volume group on any one of the physical volumes:

# vgcreate <volume_group> <physical_volume>

For example:

# vgcreate VolGroup00 /dev/sda2

See for a list of valid characters for volume group names.

Extending the volume group is just as easy:

# vgextend <volume_group> <physical_volume>

For example, to add both and to your volume group:

# vgextend VolGroup00 /dev/sdb1
# vgextend VolGroup00 /dev/sdc

You can track how your volume group grows with:

# vgdisplay

This is also what you would do if you wanted to add a disk to a RAID or mirror group with failed disks.

Combined creation of physical volumes and volume groups

LVM allows you to combine the creation of a volume group and the physical volumes in one easy step. For example, to create the group VolGroup00 with the three devices mentioned above, you can run:

# vgcreate VolGroup00 /dev/sda2 /dev/sdb1 /dev/sdc

This command will first set up the three partitions as physical volumes (if necessary) and then create the volume group with the three volumes. The command will warn you if it detects an existing filesystem on any devices.

Create logical volumes

Now we need to create logical volumes on this volume group. You create a logical volume with the next command by specifying the new volume's name and size, and the volume group it will reside on:

# lvcreate -L <size> <volume_group> -n <logical_volume>

For example:

# lvcreate -L 10G VolGroup00 -n lvolhome

This will create a logical volume that you can access later with . Just like volume groups, you can use any name you want for your logical volume when creating it besides a few exceptions listed in .

You can also specify one or more physical volumes to restrict where LVM allocates the data. For example, you may wish to create a logical volume for the root filesystem on your small SSD, and your home volume on a slower mechanical drive. Simply add the physical volume devices to the command line, for example:

# lvcreate -L 10G VolGroup00 -n lvolhome /dev/sdc1

To use all the free space left in a volume group, use the next command:

# lvcreate -l 100%FREE  <volume_group> -n <logical_volume>

You can track created logical volumes with:

# lvdisplay

Format and mount logical volumes

Your logical volumes should now be located in /dev/YourVolumeGroupName/. If you cannot find them, use the next commands to bring up the module for creating device nodes and to make volume groups available:

# modprobe dm_mod
# vgscan
# vgchange -ay

Now you can format your logical volumes and mount them as normal partitions (see mount a file system for additional details):

# mkfs.<fstype> /dev/<volume_group>/<logical_volume>
# mount /dev/<volume_group>/<logical_volume> /<mountpoint>

For example:

# mkfs.ext4 /dev/VolGroup00/lvolhome
# mount /dev/VolGroup00/lvolhome /home

Configure the system

Adding mkinitcpio hooks

In case your root filesystem is on LVM, you will need to enable the appropriate mkinitcpio hooks, otherwise your system might not boot. Enable:

• and lvm2 for the default busybox-based initramfs
• systemd and lvm2 for systemd-based initramfs

is there by default. Edit the file and insert lvm2 between  and  like so:

For systemd based initramfs:

Afterwards, you can continue in normal installation instructions with the create an initial ramdisk step.

Configure mkinitcpio for RAID

If your root filesystem is on LVM RAID additionally to the lvm2 hook, you need to add and the appropriate RAID modules (e.g. , raid1, and/or ) to the MODULES array in . Also module is needed if you created RAID with integrity checksums ( option in lvcreate).

For busybox based initramfs:

For systemd based initramfs:

For systems using LVM thin volumes the location of systemd between udev and block causes the malfunction of the thin volume. just with the parameters (base udev autodetect modconf block lvm2 filesystems keyboard fsck) works: root FS inside a lvm logical volume, and other LVM's (normal and thin) at other locations.

Kernel boot options

If the root file system resides in a logical volume, the kernel parameter must be pointed to the mapped device, e.g .