FFS (Amiga)

The Amiga Fast File System, to put it bluntly, is not - or rather, it's fast only when compared to the OFS, the Original File System of AmigaOS 1.x.

About Amiga FFS

There are many bright design ideas making the AmigaOS a very special thing, but the file system was not exactly part of it. It is prone to invalidation, holds redundant data, and its directory structure is comparatively slow to traverse. It also lacks any concept of multi-user environments.

Perhaps the only good thing with the Amiga FFS was the concept of the Rigid Disk Block (RDB) - a special area at the beginning of a disk, holding not only the partitioning information. It was also possible to store a file system there - a module that would tell a different AmigaOS machine how to read a partition if it was not formatted in FFS format but something else.

For those interested in its internals should try to find a copy of "The Amiga Guru Book" by Ralph Babel, which holds a complete reference of its rather complex block structure. (It also has a complete reference of the DOS library, as well as interesting information on various internals of the Amiga architecture. It is long out of print, but perhaps you can still find copies on eBay.) The old FAQ also held some info in the internals, which are preserved in the AmigaFFS Document.