Amiga Fast File System
| Features | |
|---|---|
| Attributes | filenote |
| Transparent compression | No |
| Transparent encryption | No |
| Other | |
| Supported operating systems | AmigaOS |
The Amiga Fast File System (abbreviated AFFS, or more commonly historically as FFS, not to be confused with the identically named Berkeley Unix FFS) is a file system used on the Amiga personal computer. The previous Amiga filesystem was never given a specific name and known originally simply as "DOS" or AmigaDOS. Upon the release of FFS, the original filesystem became known as Amiga Old File System (OFS). OFS, which was primarily designed for use with floppy disks, had been proving slow to keep up with hard drives of the era. FFS was designed as a full replacement for the original Amiga filesystem. FFS differs from its predecessor mainly in the removal of redundant information. Data blocks contain nothing but data, allowing the filesystem to manage the transfer of large chunks of data directly from the host adapter to the final destination.
OFS was the predecessor to FFS. Before FFS was released, AmigaOS had a single filesystem simply called AmigaDOS: this uses 24 bytes per sector for redundancy data, providing for reconstructing structural data on less reliable media such as floppy disks. When higher-speed media (i.e. hard disks) became more available to the Amiga, this redundant data posed a bottleneck as all data needed to be realigned to be passed to the application. The redundancy was removed with FFS and the data read in from media are passed to the application directly. The previous filesystem, AmigaDOS, was renamed OFS, Old File System, to differentiate between it and FFS. FFS was backward-compatible and could access devices formatted with OFS.
Given these advantages, FFS was rapidly adopted as the most common filesystem used by almost all Amiga users, although OFS continued to be widely used on floppy disks from third-party software vendors. (This was purely for compatibility with pre-AmigaOS 2 systems in games and applications that did not actually require AmigaOS 2+, as machines running earlier versions of the OS without FFS in the ROM could not boot from these floppies, although they could still read them if they had FFS installed.)
Amiga FFS is simple and efficient, and when introduced was more than adequate, and had many advantages compared to the file systems of other platforms. However, as OFS had done before it, it aged; as drives became larger and the number of files on them increased, its use as a day-to-day filesystem became more problematic in terms of difficulty of maintenance and competitiveness of general performance. Despite this, it is still used on AmigaOS systems and shipped with both MorphOS and AmigaOS 4.
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