Btrfs
File system for Linux / From Wikipedia, the free encyclopedia
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Btrfs (pronounced as "better F S",[8] "butter F S",[11][12] "b-tree F S",[12] 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 with Linux's LVM), developed together. It was founded by Chris Mason in 2007[13] for use in Linux, and since November 2013, the file system's on-disk format has been declared stable in the Linux kernel.[14]
| Developer(s) | SUSE, Meta, Western Digital, Oracle Corporation, Fujitsu, Fusion-io, Intel, The Linux Foundation, Red Hat, and Strato AG[1] |
|---|---|
| Full name | B-tree file system |
| Introduced | Linux kernel 2.6.29, March 2009; 14 years ago (2009-03) |
| Structures | |
| Directory contents | B-tree |
| File allocation | Extents |
| Bad blocks | None recorded |
| Limits | |
| Max volume size | 16 EiB[2][lower-alpha 1] |
| Max file size | 16 EiB[2][lower-alpha 1] |
| Max no. of files | 264[lower-alpha 2][3] |
| Max filename length | 255 ASCII characters (fewer for multibyte character encodings such as Unicode) |
| Allowed filename characters | All except '/' and NUL ('\0') |
| Features | |
| Dates recorded | Creation (otime),[4] modification (mtime), attribute modification (ctime), and access (atime) |
| Date range | 64-bit signed int offset from 1970-01-01T00:00:00Z[5] |
| Date resolution | Nanosecond |
| Attributes | POSIX and extended attributes |
| File system permissions | Unix permissions, POSIX ACLs |
| Transparent compression | Yes (zlib, LZO[6] and (since 4.14) ZSTD[7]) |
| Transparent encryption | Planned[8] |
| Data deduplication | Yes[9] |
| Copy-on-write | Yes |
| Other | |
| Supported operating systems | Linux, ReactOS[10] |
| Website | docs |
Btrfs is intended to address the lack of pooling, snapshots, checksums, and integral multi-device spanning in Linux file systems.[8] Chris Mason, the principal Btrfs author, stated that its goal was "to let [Linux] scale for the storage that will be available. Scaling is not just about addressing the storage but also means being able to administer and to manage it with a clean interface that lets people see what's being used and makes it more reliable".[15]