bcachefs

Next-generation copy-on-write filesystem tools

TLDR

Format a partition with bcachefs

$ sudo bcachefs format [path/to/partition]

Mount a bcachefs filesystem

$ sudo bcachefs mount [path/to/partition] [path/to/mountpoint]

Create a RAID with SSD cache and HDD storage

$ sudo bcachefs format -l ssd.ssd1 [path/to/ssd] -l hdd.hdd1 [path/to/hdd] --replicas 1 --foreground_target ssd --promote_target ssd --background_target hdd

Mount a multidevice filesystem

$ sudo bcachefs mount [path/to/partition1]:[path/to/partition2] [path/to/mountpoint]

Display disk usage

$ bcachefs fs usage -h [path/to/mountpoint]

Set replicas after formatting

$ sudo bcachefs set-fs-option --metadata_replicas [2] --data_replicas [2] [path/to/partition]

Force rereplicate all files

$ sudo bcachefs data rereplicate [path/to/mountpoint]

Create a snapshot of a directory

$ bcachefs subvolume snapshot [path/to/directory] [path/to/snapshot]

SYNOPSIS

bcachefs command [options] [arguments]

bcachefs is a next-generation copy-on-write filesystem for Linux that combines features of btrfs and ZFS with the performance characteristics of bcache. It provides checksumming, compression, encryption, snapshots, and multi-device support.The filesystem supports tiered storage with automatic data movement between fast (SSD) and slow (HDD) devices, making it suitable for hybrid storage configurations.

SUBCOMMANDS

format

Create a new bcachefs filesystem.

mount

Mount a bcachefs filesystem.

fsck

Check and repair a filesystem.

fs usage

Display filesystem disk usage.

device

Manage devices in a filesystem (add, remove, evacuate, set state).

subvolume

Manage subvolumes and snapshots.

data rereplicate

Rewrite data so all extents meet their replication requirements.

set-fs-option

Change filesystem options on a mounted or offline filesystem.

show-super

Print the contents of a filesystem superblock.

unlock

Unlock an encrypted filesystem before mounting.

INSTALL

sudo dnf install bcachefs-tools

sudo pacman -S bcachefs-tools

sudo apk add bcachefs-tools

nix profile install nixpkgs#bcachefs-tools

CAVEATS

bcachefs was merged into the mainline Linux kernel in version 6.7 (released January 2024). Older kernels require building the external module. The filesystem is still under active development; keep backups of important data. The bcachefs userspace tools must match the on-disk format expected by your kernel.

HISTORY

bcachefs was developed by Kent Overstreet, who also created bcache. Development began around 2015 as an evolution of bcache into a full-fledged filesystem, and it was merged into mainline Linux in kernel 6.7 in early 2024.

RESOURCES

Homepage · Source code · Documentation