Assumption
Log-structured file systems are based on the assumption that files are cached in main memory and that increasing memory sizes will make the caches more and more effective at satisfying read requests. As a result, disk traffic will become dominated by writes.
Problems of existing file systems
- 1. Spread information around the disk (separate inode from file content).
- 2. File systems tend to write synchronously: the application must wail for the write rather than continuing while the write is handled in the background.
Log-structured file system
The goal is to improve write performance by buffering a sequence of file system changes in the file cache and then writing all the changes to disk sequentially in a single disk write operation.
Two key design issues:
- 1. How to retrieve information from the log.
- 2. How to manage the free space on disk.
Reference
http://www.cs.berkeley.edu/~brewer/cs262/LFS.pdf
No comments:
Post a Comment