3.9. BTRFS

Warning

BTRFS integration is currently a technology preview in Proxmox VE.

BTRFS is a modern copy on write file system natively supported by the Linux kernel, implementing features such as snapshots, built-in RAID and self healing via checksums for data and metadata. Starting with Proxmox VE 7.0, BTRFS is introduced as optional selection for the root file system.

General BTRFS advantages

Caveats

When you install using the Proxmox VE installer, you can choose BTRFS for the root file system. You need to select the RAID type at installation time:

RAID0

Also called “striping”. The capacity of such volume is the sum of the capacities of all disks. But RAID0 does not add any redundancy, so the failure of a single drive makes the volume unusable.

RAID1

Also called “mirroring”. Data is written identically to all disks. This mode requires at least 2 disks with the same size. The resulting capacity is that of a single disk.

RAID10

A combination of RAID0 and RAID1. Requires at least 4 disks.

The installer automatically partitions the disks and creates an additional subvolume at /var/lib/pve/local-btrfs. In order to use that with the Proxmox VE tools, the installer creates the following configuration entry in /etc/pve/storage.cfg:

dir: local
        path /var/lib/vz
        content iso,vztmpl,backup
        disable

btrfs: local-btrfs
        path /var/lib/pve/local-btrfs
        content iso,vztmpl,backup,images,rootdir

This explicitly disables the default local storage in favor of a btrfs specific storage entry on the additional subvolume.

The btrfs command is used to configure and manage the btrfs file system, After the installation, the following command lists all additional subvolumes:

# btrfs subvolume list /
ID 256 gen 6 top level 5 path var/lib/pve/local-btrfs

This section gives you some usage examples for common tasks.