2021-11-30 15:00:48 +00:00
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Introduction
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============
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BTRFS is a modern copy on write (COW) filesystem for Linux aimed at
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implementing advanced features while also focusing on fault tolerance, repair
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and easy administration. Its main features and benefits are:
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2023-10-30 22:15:31 +00:00
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* Snapshots which do not make a full copy of the files
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* Built-in volume management, support for software-based RAID 0, RAID 1, RAID 10 and others
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* Self-healing - checksums for data and metadata, automatic detection of silent data corruptions
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2021-11-30 15:00:48 +00:00
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Feature overview:
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2023-10-30 22:15:31 +00:00
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* Extent based file storage
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* 2\ :sup:`64` byte == 16 EiB maximum file size (practical limit is 8 EiB due to Linux VFS)
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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, read-only snapshots
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* Subvolumes (separate internal filesystem roots)
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* Checksums on data and metadata (crc32c, xxhash, sha256, blake2b)
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* Compression (ZLIB, LZO, ZSTD), heuristics
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* Integrated multiple device support
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* File Striping
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* File Mirroring
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* File Striping+Mirroring
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* Single and Dual Parity implementations (experimental, not production-ready)
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* SSD (flash storage) awareness (TRIM/Discard for reporting free blocks for
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reuse) and optimizations (e.g. avoiding unnecessary seek optimizations,
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sending writes in clusters, even if they are from unrelated files. This
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results in larger write operations and faster write throughput)
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* Efficient incremental backup
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* Background scrub process for finding and repairing errors of files with redundant copies
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* Online filesystem defragmentation
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* Offline filesystem check
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* In-place conversion of existing ext2/3/4 and reiserfs file systems
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* Seed devices. Create a (readonly) filesystem that acts as a template to seed
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other Btrfs filesystems. The original filesystem and devices are included as
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a readonly starting point for the new filesystem. Using copy on write, all
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modifications are stored on different devices; the original is unchanged.
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* Subvolume-aware quota support
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* Send/receive of subvolume changes
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* Efficient incremental filesystem mirroring
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* Batch, or out-of-band deduplication (happens after writes, not during)
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* Swapfile support
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* Tree-checker, post-read and pre-write metadata verification
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* Zoned mode support (SMR/ZBC/ZNS friendly allocation)
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