BTRFS: The Linux B-Tree Filesystem
BTRFS: The Linux B-Tree Filesystem
复制标题
DOI：
10.1145/2501620.2501623
复制
发表时间：
2013-08
期刊：
影响因子：
--
通讯作者：
O. Rodeh;Josef Bacik;Chris Mason
中科院分区：
文献类型：
--
作者：
O. Rodeh;Josef Bacik;Chris Mason
BTRFS是一个Linux文件系统，在某些流行的Linux版本中被用作默认文件系统。它基于写时拷贝，允许高效的快照和克隆。它使用B树作为其主要的磁盘数据结构。设计目标是在许多用例和工作负载下都能很好地工作。为此，许多工作都致力于在文件系统老化时保持甚至性能，而不是试图支持特定的狭窄基准用例。Linux文件系统安装在智能手机和企业服务器上。这意味着在许多不同方面的挑战。- 可扩展性。文件系统必须在多个维度上进行扩展：磁盘空间、内存和CPU。数据完整性。丢失数据不是一种选择，并且花费了大量精力来保护内容。这包括校验和、元数据复制和文件系统中内置的RAID支持。- 磁盘多样性。该系统应该与SSD和硬盘配合使用。它还有望能够使用不同大小的磁盘阵列，这对RAID和条带化机制提出了挑战。本文描述了这个文件系统的核心思想、数据结构和算法。它揭示了在存在快照的情况下碎片整理所带来的挑战，以及在面对各种工作负载时保持均匀性能所需的权衡。
BTRFS is a Linux filesystem that has been adopted as the default filesystem in some popular versions of Linux. It is based on copy-on-write, allowing for efficient snapshots and clones. It uses B-trees as its main on-disk data structure. The design goal is to work well for many use cases and workloads. To this end, much effort has been directed to maintaining even performance as the filesystem ages, rather than trying to support a particular narrow benchmark use-case. Linux filesystems are installed on smartphones as well as enterprise servers. This entails challenges on many different fronts. ---Scalability. The filesystem must scale in many dimensions: disk space, memory, and CPUs. ---Data integrity. Losing data is not an option, and much effort is expended to safeguard the content. This includes checksums, metadata duplication, and RAID support built into the filesystem. ---Disk diversity. The system should work well with SSDs and hard disks. It is also expected to be able to use an array of different sized disks, which poses challenges to the RAID and striping mechanisms. This article describes the core ideas, data structures, and algorithms of this filesystem. It sheds light on the challenges posed by defragmentation in the presence of snapshots, and the tradeoffs required to maintain even performance in the face of a wide spectrum of workloads.