> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/di-25-zhang-ufs-wen-jian-xi-tong/di-25.1-jie-ufs-wen-jian-xi-tong-gai-shu.md).

# 25.1 UFS 文件系统概述

UFS（UNIX File System，全称 UNIX 文件系统）是 FreeBSD 的原生文件系统，基于伯克利快速文件系统（Berkeley Fast File System，FFS），由 Kirk McKusick、Bill Joy 等人于 1983 年随 4.2BSD 首次引入，当前版本为 UFS2。历史上，macOS 也曾使用该文件系统作为根文件系统。本章介绍磁盘添加、磁盘扩容、快照创建与挂载、配额管理以及磁盘加密五类操作。

需要区分本节所述的 UFS 文件系统与手机等设备中使用的 UFS 存储属于完全不同的技术范畴。后者全称为 Universal Flash Storage（通用闪存存储），是一种硬件存储标准，目前已发展至 5.0 版本（2026 年）。FreeBSD 自 7.x 起通过 mmc/mmcsd 驱动提供基本的 MMC/SD 支持，FreeBSD 10.4 实现了完整的 eMMC 支持（包括分区、TRIM 及 HS400 总线速度模式），FreeBSD 15.0 已通过 `ufshci` 驱动支持 UFS 存储。

作为文件系统的 UFS 当前版本号为 2。基于 Linux 的 Android 系统不支持 UFS 文件系统，此类设备的根文件系统通常为 ext4，部分新设备采用 F2FS，而 Linux 对 UFS 的读写支持尚不完整。

## 参考文献

* Jaeyoon Choi. Universal Flash Storage on FreeBSD\[EB/OL]. \[2026-04-16]. <https://freebsdfoundation.org/our-work/journal/browser-based-edition/freebsd-15-0/universal-flash-storage-on-freebsd/>. 该文介绍了 FreeBSD UFS 驱动的开发过程及当前状态。
* McKusick M K. 4.4BSD 操作系统设计与实现\[M]. 李善平,刘文峰,马天驰,译. 北京: 机械工业出版社, 2012. 该书第 7 章详细描述了 FFS 的设计与历史。
* McKusick M K, Joy W N, Leffler S J, et al. A Fast File System for UNIX\[J]. ACM Transactions on Computer Systems, 1984, 2(3): 181-197. FFS 原始论文，首次系统阐述了伯克利快速文件系统的设计与实现。


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