The Professional File System is a
filesystem originally developed commercially for the
Amiga
Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...
, now distributed on
Aminet
Aminet is the world's largest archive of Amiga-related software and files. Aminet was originally hosted by several universities' FTP sites, and is now available on CD-ROM and on the web. According to Aminet, as of 3 September 2022, it has 83930 pac ...
with a 4-clause
BSD license
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD lic ...
. It is a compatible successor of AmiFileSafe (AFS), with an emphasis on added reliability and speed compared to standard Amiga filesystems.
It also features multi-user abilities like the older
MuFS.
The device is split into two main areas. At the beginning of the device is the metadata section, which consists of a root block, and a generic array of blocks that can be allocated to store metadata. The rest of the device is another contiguous generic array of blocks that can be allocated to store data. The metadata section usually uses a few percent of the device, depending on the size of the device.
The metadata is stored as a tree of single blocks in the metadata section. The entire directory structure is recorded in the metadata, so the data section purely contains data from files. The metadata describes the location of data in files with extents of blocks, which makes the metadata quite compact.
When a metadata update occurs, the system looks at the block containing the metadata to be changed, and copies it to a newly allocated block from the metadata section, with the change made, then it recursively changes the metadata in the block that points to that block in the same way. This way, eventually the root block needs to be changed, which causes the atomic metadata update.
The filesystem is reasonably good at keeping files unfragmented, although there is a defragmentation tool available which will work on an online filesystem.
It was the first filesystem to introduce the concept of the
Recycle Bin
A recycling bin (or recycle bin) is a container used to hold recyclables before they are taken to recycling centers. Recycling bins exist in various sizes for use inside and outside of homes, offices, and large public facilities. Separate conta ...
natively at filesystem-level to the Amiga, holding the last few deleted files in a hidden directory on the disk root.
PFS version 5.3 was developed in C and a small portion of assembly code by Michiel Pelt.
See also
*
Amiga Old File System
On the Amiga, the Old File System, sometimes also called ''Amiga File System'', was the filesystem for AmigaOS before the Amiga Fast File System. Even though it used 512-byte blocks, it reserved the first small portion of each block for metadata, ...
*
Amiga Fast File System
The Amiga Fast File System (abbreviated AFFS, or more commonly historically as FFS) is a file system used on the Amiga personal computer from the computer-manufacturer Commodore Int'l.. The previous Amiga filesystem was never given a specific ...
*
Smart File System
*
File system
*
List of file systems
The following lists identify, characterize, and link to more thorough information on file systems.
Many older operating systems support only their one "native" file system, which does not bear any name apart from the name of the operating system i ...
References
External links
Official repositoryPFS3 All-In-One
{{File systems
Disk file systems
Amiga software
AmigaOS
MorphOS software
AROS software
Free system software