The Smart File System (SFS) is a journaling filesystem used on Amiga computers and AmigaOS-derived operating systems (though some support also exists for IBM PC compatibles). It is designed for performance, scalability and integrity, offering improvements over standard Amiga filesystems as well as some special or unique features.

Features

SFS uses block sizes ranging from 512 (2<sup>9</sup>) to 32768 (2<sup>15</sup>) bytes with a maximum partition size of 128 GB.

Its good performance, better than FFS, and lack of need for long "validation" in case of an error, is achieved by grouping multiple directory entries into a single block and by grouping meta data blocks together into clusters. A bitmap is used to keep track of free space, and file data is kept track of using extents arranged into a B+ tree structure. Unlike the original Amiga filesystems, FFS and OFS, filesystem integrity is very rarely compromised by this.

One feature of SFS that is almost unique among Amiga filesystems is its ability to defragment itself while the filesystem is in use, even for locked files.

The filesystem offers a directory containing deleted files for recovery. GRUB natively supports it, and there are free drivers to use it from UEFI.

, SFS was one of the independent filesystems still being used on Amiga computers.

Versions for AROS, AmigaOS and MorphOS are based on different branches. The Linux version is independent code.

See also

  • Amiga Old File System
  • Amiga Fast File System
  • Professional File System
  • Amiga rigid disk block
  • List of file systems

References

  • Original SFS site including technical documentation
  • OS4 SFS site