btrfs.txt

  1 
  2         BTRFS
  3         =====
  4 
  5 Btrfs is a new copy on write filesystem for Linux aimed at
  6 implementing advanced features while focusing on fault tolerance,
  7 repair and easy administration. Initially developed by Oracle, Btrfs
  8 is licensed under the GPL and open for contribution from anyone.
  9 
 10 Linux has a wealth of filesystems to choose from, but we are facing a
 11 number of challenges with scaling to the large storage subsystems that
 12 are becoming common in today's data centers. Filesystems need to scale
 13 in their ability to address and manage large storage, and also in
 14 their ability to detect, repair and tolerate errors in the data stored
 15 on disk.  Btrfs is under heavy development, and is not suitable for
 16 any uses other than benchmarking and review. The Btrfs disk format is
 17 not yet finalized.
 18 
 19 The main Btrfs features include:
 20 
 21     * Extent based file storage (2^64 max file size)
 22     * Space efficient packing of small files
 23     * Space efficient indexed directories
 24     * Dynamic inode allocation
 25     * Writable snapshots
 26     * Subvolumes (separate internal filesystem roots)
 27     * Object level mirroring and striping
 28     * Checksums on data and metadata (multiple algorithms available)
 29     * Compression
 30     * Integrated multiple device support, with several raid algorithms
 31     * Online filesystem check (not yet implemented)
 32     * Very fast offline filesystem check
 33     * Efficient incremental backup and FS mirroring (not yet implemented)
 34     * Online filesystem defragmentation
 35 
 36 
 37 
 38         MAILING LIST
 39         ============
 40 
 41 There is a Btrfs mailing list hosted on vger.kernel.org. You can
 42 find details on how to subscribe here:
 43 
 44 http://vger.kernel.org/vger-lists.html#linux-btrfs
 45 
 46 Mailing list archives are available from gmane:
 47 
 48 http://dir.gmane.org/gmane.comp.file-systems.btrfs
 49 
 50 
 51 
 52         IRC
 53         ===
 54 
 55 Discussion of Btrfs also occurs on the #btrfs channel of the Freenode
 56 IRC network.
 57 
 58 
 59 
 60         UTILITIES
 61         =========
 62 
 63 Userspace tools for creating and manipulating Btrfs file systems are
 64 available from the git repository at the following location:
 65 
 66  http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs-unstable.git
 67  git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstable.git
 68 
 69 These include the following tools:
 70 
 71 mkfs.btrfs: create a filesystem
 72 
 73 btrfsctl: control program to create snapshots and subvolumes:
 74 
 75         mount /dev/sda2 /mnt
 76         btrfsctl -s new_subvol_name /mnt
 77         btrfsctl -s snapshot_of_default /mnt/default
 78         btrfsctl -s snapshot_of_new_subvol /mnt/new_subvol_name
 79         btrfsctl -s snapshot_of_a_snapshot /mnt/snapshot_of_new_subvol
 80         ls /mnt
 81         default snapshot_of_a_snapshot snapshot_of_new_subvol
 82         new_subvol_name snapshot_of_default
 83 
 84         Snapshots and subvolumes cannot be deleted right now, but you can
 85         rm -rf all the files and directories inside them.
 86 
 87 btrfsck: do a limited check of the FS extent trees.
 88 
 89 btrfs-debug-tree: print all of the FS metadata in text form.  Example:
 90 
 91         btrfs-debug-tree /dev/sda2 >& big_output_file
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Linux/Documentation/filesystems/btrfs.txt
