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.

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