
Fedora 9最重大的一个改变是整合新文件系统ext4。ext4不会作为发行版默认的文件系统,但用户和系统管理员可以选择使用。红帽子公司Fedora项目成员和文件系统开发者Eric Sandeen在接受采访时称,ext4将会提供更大的容量支持和在线磁盘碎片整理工具,更好的性能执行和可靠性。ext3文件系统限制的最大卷为2T,ext4能够扩展到16T。
http://fedoraproject.org/wiki/Interviews/EricSandeen
本来其实基于日志的文件系统,一般都会有后台整理的进程来整理磁盘,只是很多文件系统实现的时候,在分配单个文件的时候都尽量用连续的文件块,所以磁盘整理不会经常发生。现在ext4是进一步做出让同一个文件夹的文件在物理上都分配到相邻的空间而已。其实这未必好。根据使用趋势来整理我个人觉得更合理。We never heard about Defragmentation in a Linux solution, How do you think this could help the system?
Eric Sandeen: Defragmentation can be a good tool to reclaim performance lost to poor file layout.
The XFS filesystem is one linux filesystem that I know of which has had a defragmentation utility for years. It is able to take fragmented files (those which have data blocks which are not contiguous on-disk), allocate new, more-contiguous space, and move the file blocks into this space.
The ext4 defragmenter is still in development, and it is planned to be very flexible - in addition to making single files contiguous, it will do other neat tricks such as moving all files in a directory close to each other, and free-space