A classic case of this conceptual distinction is the way that freebsd - harking back to the bsd unix world - uses unix file system v2 ufs2 to organize data on the disk and the flash file system to organize files into directories and optimize directory access 这种总体区分的一个经典例子就是freebsd回溯到bsd unix时代用unix file system v2 ( ufs2 )来组织磁盘上的数据而用flash file system ( ffs )来把文件组织成目录并最优化目录访问的方式。