The Amiga Fast File System (FFS) is an advanced file system used on the Amiga personal computer. It was originally designed for use on floppy disks, so it had the root block right in the middle of the disk (to minimise access time to other parts of the disk). Metadata tended to collect in the middle of the disk too, which improved some performance characteristics. It was block-based, with a default block size of 512 bytes. Listing directories tended to involve lots of seeks around the disk, so were quite slow. It was not really appropriate for hard drives, but used for them nonetheless. See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... Amiga is the name of a range of home/ personal computers primarily using the Motorola 68000 processor family, whose development started in 1982, initially as a game machine. ... The tower of a personal computer. ... A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ... Metadata is data about data. ... Typical hard drives of the mid-1990s. ...

As with many Amiga filesystems, it did not need to be specifically unmounted in order to mount cleanly afterwards. However, this was a bit of a con, because when a write occurred the system would mark the disk as "unclean", alter it, then mark it "clean" again. If you switched the system off half-way through this, you would have to run the "disk-doctor" over the disk, which would perform an integrity check, then sometimes rename the disk "Lazarus".

History

The FFS derives from the original Amiga filesystem, called OFS (either for Original File System or Old File System). FFS was created in order to boot hard disk, because OFS was uncapable to perform autoboot. FFS was introduced with version 1.3 of AmigaOS in 1987 for the launch of A500 and mainly of A2000 which had bus expansion slots. AmigaOS is the default native operating system of the Amiga and AmigaOne personal computers. ... Missing image A500 The A500, also known as the Amiga 500, was the first low-end Commodore Amiga 16_bit multimedia home/personal computer model. ... The A2000, also known as the Commodore Amiga 2000, is the high-end Amiga personal computer that was released in 1987 at the same time as the low-end high-volume model A500. ...

Fast File System also eliminates some little disavanteges of OFS. Infact OFS stored only 488 bytes of data per block, leaving 24 bytes of metadata for internal purposes, while FFS has access to all block size.

With version 3.0 of AmigaOS, born for the new amiga 4000 were introduced new FFS modes, called International and Directory Cache.

International mode allows FFS to handle filenames with international characters.

Directory Cache mode allows the filesystem to access hard disks more rapidly by creating a cache of directory contents. As any other directory caching based systems it used a certain amount of disk space to store the data.

Recently AmigaOS4 has introduced new FFS2 Filesystem. FastFileSystem infact resulted outdated and lacks some security of modern filesystems, while FFS2 provide multi-user support and mainly better data integrity to prevent invalid drives. It provides also backward compatibility with elder file systems.

Characteristics

The Amiga Old File System article, in the section "Characteristics" (http://en.wikipedia.org/wiki/Amiga_Old_File_System#Characteristics), presents the basic information regarding Amiga filesystems specifications. Old File System, on the Amiga. ...

See also

• OFS
• Professional File System
• Smart File System
• List of file systems

Old File System, on the Amiga. ... The Professional File System is a filesystem originally developed commercially for the Amiga. ... The Smart File System (SFS) is a journalling filesystem used on Amiga computers. ... Disk file systems ADFS – Acorn filing system, successor to DFS. BFS – the Be File System used on BeOS EFS – Encrypted filesystem, An extension of NTFS EFS (IRIX) – an older block filing system under IRIX. Ext – Extended filesystem, designed for Linux systems Ext2 – Extended filesystem 2, designed for Linux systems Ext3...

External links

• The ADFlib Page (http://lclevy.club.fr/adflib/index.html) and precisely ADF File specs (http://lclevy.club.fr/adflib/adf_info.html)
• The ADF specs (ftp://it.aminet.net/pub/aminet/disk/misc/ADFlib.lha), in LHA format from Aminet