日志结构文件系统技术的研究

The Analysis of Log-Structured File System

介绍了一种新的磁盘管理技术———日志结构文件系统。把对文件的修改汇成日志条目顺序地写入磁盘 ,既加速了写文件的速度 ,又加速了崩溃恢复的速度。把整个磁盘作为日志 ,磁盘上包含有效的读取日志结构文件所需的索引信息。为了保持快速写所需的大的磁盘空闲快 ,将磁盘分成段 ,用一个清理工线程收集压缩分散到各个段中的有效信息。以一个日志结构文件系统的原型 ,即SpriteLFS为例 ,对日志文件系统设计和实现的各个阶段进行了分析 ,并与Unix的文件系统 ,即快速文件系统 (FFS)进行了比较。

This paper presents a new technique for disk storage management called a log structured file system. A log structured file system writes all modifications to disk sequentially in a log like structure,thereby speeding up both file writing and crash recovery. The log is the only structure on disk;it contains indexing information so that files can be read back from the log efficiently.In order to maintain large free areas on disk for fast writing,we divide the log into segments and use a segment cleaner to compress the live information from heavily fragmented segments.This paper takes a log structured file system:Sprite LFS as an example and analyzes its design and implementation,the comparison of Sprite with FFS is also made.