daveh@xtenk.sgi.com (David A Higgen) (09/22/89)
> Can anyone tell me what an "Extent File System" is (compared to a "normal" > Unix System V file system). I see it mentioned in nearly every SGI document > but I haven't been able to find and explaination of what the benefits are. > > Thanks! --Pete Poorman 'man fs' will give you some basic information. There are also extensive explanatory comments in several of the include/sys/fs header files. Particularly efs_fs.h and efs_sb.h. The main benefit over a sysV filesystem is speed: space for files is allocated not on a one-by-one block basis but in chunks ("extents") of contiguous blocks which may be up to 248 blocks in size. So I/O happens in larger, faster, units. Dave Higgen