下一代 Linux 文件系統 Btrfs

openkk 12年前發布 | 16K 次閱讀文件系統分布式/云計算/大數據

Btrfs（通常念成Butter FS），是由Oracle于2007年宣布并進行中的copy-on-write文件系統。目標是取代Linux目前的ext3文件系統，改善ext3的限制，特別是單個文件的大小，總文件系統大小或文件檢查和加入ext3未支持的功能，像是可寫快照（writable snapshots）、快照的快照（snapshots of snapshots）、內建磁盤陣列（RAID），以及子卷（subvolumes）。Btrfs 也宣稱專注在“容錯、修復及易于管理”。

The main Btrfs features available at the moment include:

Extent based file storage
2^64 byte == 16 EiB maximum file size
Space-efficient packing of small files
Space-efficient indexed directories
Dynamic inode allocation
Writable snapshots, read-only snapshots
Subvolumes (separate internal filesystem roots)
Checksums on data and metadata
Compression (zlib and LZO)
Integrated multiple device support
- File Striping, File Mirroring, and File Striping+Mirroring implementations
SSD (Flash storage) awareness (TRIM/Discard for reporting free blocks for reuse) and optimizations (e.g. avoiding unnecessary seek optimizations, sending writes in clusters, even if they are from unrelated files. This results in larger write operations and faster write throughput)
Efficient incremental backup
Background scrub process for finding and fixing errors on files with redundant copies
Online filesystem defragmentation
Offline filesystem check
Conversion of existing ext3/4 file systems
Seed devices. 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.