2009-01-07 22:54:24 +08:00
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BTRFS
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=====
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Btrfs is a new copy on write filesystem for Linux aimed at
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implementing advanced features while focusing on fault tolerance,
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repair and easy administration. Initially developed by Oracle, Btrfs
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is licensed under the GPL and open for contribution from anyone.
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Linux has a wealth of filesystems to choose from, but we are facing a
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number of challenges with scaling to the large storage subsystems that
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are becoming common in today's data centers. Filesystems need to scale
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in their ability to address and manage large storage, and also in
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their ability to detect, repair and tolerate errors in the data stored
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on disk. Btrfs is under heavy development, and is not suitable for
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any uses other than benchmarking and review. The Btrfs disk format is
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not yet finalized.
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The main Btrfs features include:
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* Extent based file storage (2^64 max file size)
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* Space efficient packing of small files
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* Space efficient indexed directories
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* Dynamic inode allocation
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* Writable snapshots
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* Subvolumes (separate internal filesystem roots)
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* Object level mirroring and striping
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* Checksums on data and metadata (multiple algorithms available)
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* Compression
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* Integrated multiple device support, with several raid algorithms
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* Online filesystem check (not yet implemented)
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* Very fast offline filesystem check
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* Efficient incremental backup and FS mirroring (not yet implemented)
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* Online filesystem defragmentation
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MAILING LIST
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============
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There is a Btrfs mailing list hosted on vger.kernel.org. You can
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find details on how to subscribe here:
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http://vger.kernel.org/vger-lists.html#linux-btrfs
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Mailing list archives are available from gmane:
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http://dir.gmane.org/gmane.comp.file-systems.btrfs
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IRC
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===
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Discussion of Btrfs also occurs on the #btrfs channel of the Freenode
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IRC network.
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UTILITIES
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=========
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Userspace tools for creating and manipulating Btrfs file systems are
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available from the git repository at the following location:
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2011-11-17 00:35:37 +08:00
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http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs.git
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git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
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2009-01-07 22:54:24 +08:00
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These include the following tools:
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mkfs.btrfs: create a filesystem
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btrfsctl: control program to create snapshots and subvolumes:
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mount /dev/sda2 /mnt
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btrfsctl -s new_subvol_name /mnt
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btrfsctl -s snapshot_of_default /mnt/default
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btrfsctl -s snapshot_of_new_subvol /mnt/new_subvol_name
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btrfsctl -s snapshot_of_a_snapshot /mnt/snapshot_of_new_subvol
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ls /mnt
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default snapshot_of_a_snapshot snapshot_of_new_subvol
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new_subvol_name snapshot_of_default
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Snapshots and subvolumes cannot be deleted right now, but you can
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rm -rf all the files and directories inside them.
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btrfsck: do a limited check of the FS extent trees.
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btrfs-debug-tree: print all of the FS metadata in text form. Example:
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btrfs-debug-tree /dev/sda2 >& big_output_file
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