Btrfs: Difference between revisions

Latest revision as of 01:53, 26 October 2020

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Btrfs: the b-tree filesystem

Btrfs is a copy-on-write filesystem for Linux aimed at implementing advanced features including error detection, fault tolerance, recovery, transparent compression, cheap snapshots, integrated volume management, and easy administration. It provides multiple device storage pooling, RAID-like functionality, fast snapshot creation, and checksumming of data and metadata. Contributors include Facebook, Fujitsu, (open)SUSE, Oracle, and Western Digital. Btrfs is licensed under the GPL and open for contribution from anyone.

Default filesystem, on the desktop

Btrfs is the default file system for desktops, starting with Fedora 33. See the Change Proposal
Fedora Magazine: Btrfs Coming to Fedora 33

Reporting bugs

Bugs related to btrfs user-space commands should be filed against the btrfs-progs component.
All other bugs should be filed against the kernel component. Following submission of the bug, please set the Assignee field to: fedora-kernel-btrfs@fedoraproject.org and Save the change.

Installer support

The Fedora installer, Anaconda, uses Btrfs by default in desktop editions and spins; and as an option in Manual Partitioning for Server, Cloud, and IoT editions. Fedora CoreOS installer, Ignition, also supports Btrfs as an option.
The Btrfs partition scheme preset creates an ext4 /boot, and a Btrfs pool. Two subvolumes, root and home, are created from that pool and mounted at / and /home respectively.
Additional mount points using Btrfs will also have corresponding subvolumes created based on the Name field. Subvolumes do not have a size, so the Desired Capacity field when creating new mount points is ignored and can be left blank.

Conversion from Ext3/Ext4 volumes to Btrfs (and back!)

Btrfs has it's own volume management capability. If you are using ext4 on LVM, converting the volume to Btrfs does not remove LVM. It also doesn't create the subvolume layout that we're using in Anaconda and image builders.

Btrfs Wiki has more information on conversion and rollback.

Upstream Development

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-= Btrfs filesystem =
+{{autolang|base=yes}}
-== Summary ==
+===Btrfs: the b-tree filesystem===
-Btrfs is a copy on write filesystem for Linux aimed at implementing advanced features while focusing on fault tolerance, repair and easy administration. It provides multiple device storage pooling, RAID-like functionality, fast snapshot creation, and checksumming of data and metadata. Initially developed by Oracle, Btrfs is licensed under the GPL and open for contribution from anyone.
+Btrfs is a copy-on-write filesystem for Linux aimed at implementing advanced features including error detection, fault tolerance, recovery, transparent compression, cheap snapshots, integrated volume management, and easy administration. It provides multiple device storage pooling, RAID-like functionality, fast snapshot creation, and checksumming of data and metadata. Contributors include Facebook, Fujitsu, (open)SUSE, Oracle, and Western Digital. Btrfs is licensed under the GPL and open for contribution from anyone.
-For more detailed information can be found at the [https://btrfs.wiki.kernel.org/index.php/Main_Page Btrfs homepage].
+===Default filesystem, on the desktop===
+* Btrfs is the default file system for desktops, starting with Fedora 33. See the [https://fedoraproject.org/wiki/Changes/BtrfsByDefault Change Proposal]
+* [https://fedoramagazine.org/btrfs-coming-to-fedora-33/ Fedora Magazine: Btrfs Coming to Fedora 33]
-== Purpose ==
+===Reporting bugs===
-This page provides Fedora specific information on Btrfs support.
+* Bugs related to <code>btrfs</code> user-space commands should be filed against the <span style="color: blue">btrfs-progs</span> component.
+* All other bugs should be filed against the <span style="color: blue">kernel</span> component. Following submission of the bug, please set the Assignee field to: <span style="color: blue">fedora-kernel-btrfs@fedoraproject.org</span> and Save the change.
-== Stability status and support ==
+===Installer support===
-Fedora maintains fairly recent kernels and btrfs-progs that are typically identical to upstream. The best resources are the Btrfs Wiki and mailing list.
+* The Fedora installer, Anaconda, uses Btrfs by default in desktop editions and spins; and as an option in Manual Partitioning for Server, Cloud, and IoT editions. Fedora CoreOS installer, Ignition, also supports Btrfs as an option.
+* The Btrfs partition scheme preset creates an ext4 /boot, and a Btrfs pool. Two subvolumes, root and home, are created from that pool and mounted at / and /home respectively.
-The current [https://btrfs.wiki.kernel.org/index.php/Status stability status] page.
+* Additional mount points using Btrfs will also have corresponding subvolumes created based on the Name field. Subvolumes do not have a size, so the Desired Capacity field when creating new mount points is ignored and can be left blank.
-[https://btrfs.wiki.kernel.org/index.php/Btrfs_mailing_list Mailing list] information.
-== Btrfs support in Fedora ==
-* Btrfs has been available as an installation time option as early as Fedora 11.
-* All Fedora products include Btrfs support in the kernel, and user space tools are installed by default.
-== Installing ==
+===Recommended reading for users===
-* The Fedora installer, Anaconda, provides Btrfs as an option in Manual Partitioning.
+====Basics====
-* The Btrfs partition scheme preset creates an ext4 /boot, swap, and a Btrfs pool. Two subvolumes, root and home, are created from that pool and mounted at / and /home respectively.
+* `man 5 btrfs` — info about btrfs itself: mount options, features, limits, swapfile support, the case of multiple block group profiles
-* Additional mount points using Btrfs will also have corresponding subvolumes created based on the Name field. Subvolumes do not have a size, so the Desired Capacity field when creating new mount points is ignored and can be left blank.
+* `man btrfs` — btrfs user space commands overview
+* `man btrfs <command>` — man page for this specific btrfs command, e.g. `man btrfs device`. NOTE: Any command name can be shortened so long as the shortened form is unambiguous, e.g. `btrfs fi us` is equivalent to `btrfs filesystem usage`.
+* `man mkfs.btrfs` — man page for the mkfs command, includes info on block groups, chunks, raid, multiple device layouts, profiles, redundancy, space utilization, and minimum devices.
+====Intermediate====
+* [https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Layout Btrfs Sysadmin Guide: Subvolume layouts]
+* [https://fedoraproject.org/wiki/User:Chrismurphy/lvm2btrfs Chart of LVM commands and their Btrfs approximates]
+====Advanced====
+* [https://raid.wiki.kernel.org/index.php/Timeout_Mismatch linux-raid@ list: Timeout Mismatch]
+* [https://lore.kernel.org/linux-btrfs/20200627032414.GX10769@hungrycats.org/ linux-btrfs@ list: How to use btrfs raid5 successfully(ish)]
+====Developers====
+* [https://github.com/btrfs/btrfs-dev-docs Collection of documents that describe internals of the BTRFS filesystem.]
+* [https://btrfs.wiki.kernel.org/index.php/Developer%27s_FAQ Btrfs Wiki: Developer's FAQ, contributing to Btrfs.]
-== Conversions from Ext3/Ext4 volumes to Btrfs (and back!) ==
+===Conversion from Ext3/Ext4 volumes to Btrfs (and back!)===
-{{admon/important|Although Btrfs does not need LVM, if you already are using it then converting your volume does not remove LVM.}}
+{{admon/important|Btrfs has it's own volume management capability. If you are using ext4 on LVM, converting the volume to Btrfs does not remove LVM. It also doesn't create the subvolume layout that we're using in Anaconda and image builders.}}
-* The convert code has been rewritten as of btrfs-progs 4.6, it's advised to avoid older versions.
-* Check the upstream Btrfs changelog for the most recent recommended version of btrfs-progs.
-* The most recent recommended btrf-progs may not be in the Fedora repository version you're using, it can be found in Koji.
 * Btrfs Wiki has more information on [https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3 conversion and rollback.]
-== Frequently Asked Question(s) ==
+===Upstream Development===
-* Why use (or not use) Btrfs?
+* [https://btrfs.wiki.kernel.org/index.php/Changelog Btrfs Changelog].
-** Data integrity: detection of corrupt metadata and data, automatic repair when there's redundancy.
+* [https://btrfs.wiki.kernel.org/index.php/Status Stability status].
-** Fast snapshot creation, btrfs send/receive snapshots for replicating and backup.
+* [https://btrfs.wiki.kernel.org/index.php/Btrfs_mailing_list Mailing list information].
-** Online resizing and addition/removal of disks.
-** Filesystem based [http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices RAID 0/1/10/5/6]. See the Btrfs [https://btrfs.wiki.kernel.org/index.php/Status status page] for feature stability. Some features are considered experimental!
-** 'btrfs check' a.k.a. btrfsck, is safe. However, while --repair should be safe, it comes with many warnings. See 'man btrfs check'.
-** If a Btrfs volume fails to mount, try 'mount -o usebackuproot'. If that also fails report the issue on the Btrfs mailing list, including the output from 'btrfs check' without --repair.
 [[Category:btrfs|btrfs]]

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Btrfs: Difference between revisions

Latest revision as of 01:53, 26 October 2020

Contents

Btrfs: the b-tree filesystem

Default filesystem, on the desktop

Reporting bugs

Installer support

Recommended reading for users

Basics

Intermediate

Advanced

Developers

Conversion from Ext3/Ext4 volumes to Btrfs (and back!)

Upstream Development