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+
+        BTRFS
+        =====
+
+Btrfs is a new copy on write filesystem for Linux aimed at
+implementing advanced features while focusing on fault tolerance,
+repair and easy administration. Initially developed by Oracle, Btrfs
+is licensed under the GPL and open for contribution from anyone.
+
+Linux has a wealth of filesystems to choose from, but we are facing a
+number of challenges with scaling to the large storage subsystems that
+are becoming common in today's data centers. Filesystems need to scale
+in their ability to address and manage large storage, and also in
+their ability to detect, repair and tolerate errors in the data stored
+on disk.  Btrfs is under heavy development, and is not suitable for
+any uses other than benchmarking and review. The Btrfs disk format is
+not yet finalized.
+
+The main Btrfs features include:
+
+    * Extent based file storage (2^64 max file size)
+    * Space efficient packing of small files
+    * Space efficient indexed directories
+    * Dynamic inode allocation
+    * Writable snapshots
+    * Subvolumes (separate internal filesystem roots)
+    * Object level mirroring and striping
+    * Checksums on data and metadata (multiple algorithms available)
+    * Compression
+    * Integrated multiple device support, with several raid algorithms
+    * Online filesystem check (not yet implemented)
+    * Very fast offline filesystem check
+    * Efficient incremental backup and FS mirroring (not yet implemented)
+    * Online filesystem defragmentation
+
+
+
+        MAILING LIST
+        ============
+
+There is a Btrfs mailing list hosted on vger.kernel.org. You can
+find details on how to subscribe here:
+
+http://vger.kernel.org/vger-lists.html#linux-btrfs
+
+Mailing list archives are available from gmane:
+
+http://dir.gmane.org/gmane.comp.file-systems.btrfs
+
+
+
+        IRC
+        ===
+
+Discussion of Btrfs also occurs on the #btrfs channel of the Freenode
+IRC network.
+
+
+
+        UTILITIES
+        =========
+
+Userspace tools for creating and manipulating Btrfs file systems are
+available from the git repository at the following location:
+
+ http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs-unstable.git
+ git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstable.git
+
+These include the following tools:
+
+mkfs.btrfs: create a filesystem
+
+btrfsctl: control program to create snapshots and subvolumes:
+
+        mount /dev/sda2 /mnt
+        btrfsctl -s new_subvol_name /mnt
+        btrfsctl -s snapshot_of_default /mnt/default
+        btrfsctl -s snapshot_of_new_subvol /mnt/new_subvol_name
+        btrfsctl -s snapshot_of_a_snapshot /mnt/snapshot_of_new_subvol
+        ls /mnt
+        default snapshot_of_a_snapshot snapshot_of_new_subvol
+        new_subvol_name snapshot_of_default
+
+        Snapshots and subvolumes cannot be deleted right now, but you can
+        rm -rf all the files and directories inside them.
+
+btrfsck: do a limited check of the FS extent trees.
+
+btrfs-debug-tree: print all of the FS metadata in text form.  Example:
+
+        btrfs-debug-tree /dev/sda2 >& big_output_file