BTRFS is a modern copy on write (COW) filesystem for Linux aimed at implementing advanced features while also focusing on fault tolerance, repair and easy administration. Its main features and benefits are:
- Snapshots which do not make a full copy of the files
- Built-in volume management, support for software-based RAID 0, RAID 1, RAID 10 and others
- Self-healing - checksums for data and metadata, automatic detection of silent data corruptions
- Data compression
- Reflinks, fast and efficient file copies
- Extent based file storage
- 264 byte (16 EiB) :ref:`maximum file size<administration-limits>` (practical limit is 8 EiB due to Linux VFS)
- :doc:`Space-efficient packing of small files<Inline-files>`
- Space-efficient indexed directories
- :ref:`Dynamic inode allocation<administration-flexibility>`
- :doc:`Writable snapshots, read-only snapshots, subvolumes (separate internal filesystem roots)<Subvolumes>`
- :doc:`Checksums on data and metadata<Checksumming>` (crc32c, xxhash, sha256, blake2b)
- :doc:`Compression (ZLIB, LZO, ZSTD), heuristics<Compression>`
- :doc:`Integrated multiple device support<Volume-management>`:
- File Striping (like RAID0)
- File Mirroring (like RAID1 up to 4 copies)
- File Striping+Mirroring (like RAID10)
- Single and Dual Parity implementations (like RAID5/6, experimental, not production-ready)
- SSD/NVMe (flash storage) awareness, :doc:`TRIM/Discard<Trim>` for reporting free blocks for reuse and optimizations (e.g. avoiding unnecessary seek optimizations, sending writes in clusters.
- :doc:`Background scrub<Scrub>` process for finding and repairing errors of files with redundant copies
- :doc:`Online filesystem defragmentation<Defragmentation>`
- :doc:`Offline filesystem check<btrfs-check>`
- :doc:`In-place conversion<Convert>` of existing ext2/3/4 and reiserfs filesystems
- :doc:`Seeding device.<Seeding-device>` Create a (readonly) filesystem that acts as a template to seed other Btrfs filesystems. The original filesystem and devices are included as a readonly starting point for the new filesystem. Using copy on write, all modifications are stored on different devices; the original is unchanged.
- :doc:`Subvolume-aware quota<Qgroups>` support
- :doc:`Send/receive of subvolume changes<Send-receive>`, efficient incremental filesystem mirroring and backup
- :doc:`Batch, or out-of-band deduplication<Deduplication>` (happens after writes, not during)
- :doc:`Swapfile support<Swapfile>`
- :doc:`Tree-checker<Tree-checker>`, post-read and pre-write metadata verification
- :doc:`Zoned mode support<Zoned-mode>` (SMR/ZBC/ZNS friendly allocation, emulated on non-zoned devices)
A more detailed list of features and compatibility is on the :doc:`status page <Status>`.
For a really quick start you can simply create and mount the filesystem. Make sure that the block device you'd like to use is suitable so you don't overwrite existing data.
# mkfs.btrfs /dev/sdx
# mount /dev/sdx /mnt/testThe default options should be acceptable for most users and sometimes can be changed later. The example above is for a single device filesystem, creating a single profile for data (no redundant copies of the blocks), and DUP for metadata (each block is duplicated).
Read more about:
- creating a filesystem at :doc:`mkfs.btrfs`
- mount options at :doc:`Administration`