Bcachefs is a

copy-on-write Copy-on-write (COW), sometimes referred to as implicit sharing or shadowing, is a resource-management technique used in computer programming to efficiently implement a "duplicate" or "copy" operation on modifiable resources. If a resource is dupl ...

(COW) file system for

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, w ...

-based operating systems. Its primary developer, Kent Overstreet, first announced it in 2015, and efforts are ongoing to have it included in the mainline Linux kernel. It is intended to compete with the modern features of

ZFS ZFS (previously: Zettabyte File System) is a file system with volume management capabilities. It began as part of the Sun Microsystems Solaris operating system in 2001. Large parts of Solaris – including ZFS – were published under an ope ...

Btrfs Btrfs (pronounced as "better F S", "butter F S", "b-tree F S", or simply by spelling it out) is a computer storage format that combines a file system based on the copy-on-write (COW) principle with a logical volume manager (not to be confused ...

, and the speed and performance of

ext4 ext4 (fourth extended filesystem) is a journaling file system for Linux, developed as the successor to ext3. ext4 was initially a series of backward-compatible extensions to ext3, many of them originally developed by Cluster File Systems for ...

XFS XFS is a high-performance 64-bit journaling file system created by Silicon Graphics, Inc (SGI) in 1993. It was the default file system in SGI's IRIX operating system starting with its version 5.3. XFS was ported to the Linux kernel in 2001; as ...

Features

Bcachefs is a

(COW) file system for

-based operating systems. Planned or existing features for Bcachefs include caching, full file-system

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can de ...

using the ChaCha20 and

Poly1305 Poly1305 is a universal hash family designed by Daniel J. Bernstein for use in cryptography. As with any universal hash family, Poly1305 can be used as a one-time message authentication code to authenticate a single message using a key shared b ...

algorithms, native

compression Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression * Gas compression *Compression ratio, of a ...

via

zlib zlib ( or "zeta-lib", ) is a software library used for data compression. zlib was written by Jean-loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. zlib is also ...

, LZ4, and

Zstandard Zstandard, commonly known by the name of its reference implementation zstd, is a lossless data compression algorithm developed by Yann Collet at Facebook. ''Zstd'' is the reference implementation in C. Version 1 of this implementation was r ...

snapshots Snapshot, snapshots or snap shot may refer to: * Snapshot (photography), a photograph taken without preparation Computing * Snapshot (computer storage), the state of a system at a particular point in time * Snapshot (file format) or SNP, a file ...

CRC-32C A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data. Blocks of data entering these systems get a short ''check value'' attached, based on t ...

and 64-bit

checksum A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify data ...

ming. It can use multiple block devices, including in

RAID Raid, RAID or Raids may refer to: Attack * Raid (military), a sudden attack behind the enemy's lines without the intention of holding ground * Corporate raid, a type of hostile takeover in business * Panty raid, a prankish raid by male college ...

configurations. Bcachefs provides all the functionality of

Bcache bcache (abbreviated from ''block cache'') is a cache in the Linux kernel's block layer, which is used for accessing secondary storage devices. It allows one or more fast storage devices, such as flash-based solid-state drives (SSDs), to act as ...

, a block-layer

cache Cache, caching, or caché may refer to: Places United States * Cache, Idaho, an unincorporated community * Cache, Illinois, an unincorporated community * Cache, Oklahoma, a city in Comanche County * Cache, Utah, Cache County, Utah * Cache County ...

system for Linux, with which Bcachefs shares about 80% of its code.

History

Primary development has been by Kent Overstreet, the developer of

, which he describes as a "prototype" for the ideas that became Bcachefs. Overstreet intends Bcachefs to replace Bcache. Overstreet has stated that development of Bcachefs began as Bcache's developers realized that its codebase had "been evolving ... into a full blown, general-purpose

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inter ...

filesystem", and that "there was a really clean and elegant design" within it if they took it in that direction. Some time after Bcache was merged in 2013 into the mainline Linux kernel, Overstreet left his job at

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

to work full-time on Bcachefs. After a few years' unfunded development, Overstreet announced Bcachefs in 2015, at which point he called the code "more or less feature complete", and called for testers and contributors. He intended it to be an advanced file system with modern features like those of

, with the speed and performance of file systems such as

and

. As of 2017 Overstreet was receiving financial support for the development of Bcachefs via

Patreon Patreon (, ) is a membership platform that provides business tools for content creators to run a subscription service. It helps creators and artists earn a monthly income by providing rewards and perks to their subscribers. Patreon charges a com ...

. As of mid-2018, the on-disk format had settled. Patches had been submitted for review to have Bcachefs included in the mainline Linux kernel, but had not yet been accepted. By mid-2019, the desired features of Bcachefs had reached and associated patches to

LKML The Linux kernel mailing list (LKML) is the main electronic mailing list for Linux kernel development, where the majority of the announcements, discussions, debates, and flame wars over the kernel take place. Many other mailing lists exist to ...

was submitted for peer review. As of December 2022, Bcachefs has still not been merged into the mainline Linux kernel.

References

Works cited

* * * * * * * *

External links

* {{Portal bar, Free and open-source software, Linux 2015 software Compression file systems File systems supported by the Linux kernel Linux file system-related software