Unix File System in Linux | Unix File System | Linux Operating System | Learn Linux System | Linux Examples | Linux Tutorials | Linux Books

Unix File System in Linux | Unix File System | Linux Operating System | Learn Linux System | Linux Examples | Linux Tutorials | Linux Books

Unix File System in Linux | Unix File System | Linux Operating System | Learn Linux System | Linux Examples | Linux Tutorials | Linux Books

The Unix document framework (UFS; additionally called the Berkeley Fast File System, the BSD Fast File System or FFS) is a record framework utilized by numerous Unix and Unix-like working frameworks. It is a removed relative of the first filesystem utilized by Version 7 Unix.


Developer(s) CSRG

Full name UNIX record framework

Introduced with 4.2BSD


Registry contents tables

Cutoff points

Max. volume size 273 bytes (8 ZiB)

Max. record size 273 bytes (8 ZiB)

Max. filename length 255 bytes


Dates recorded UFS1 and UFS2: last access time (atime), last adjusted time (mtime), last inode change time (ctime), UFS2: inode creation time (birthtime)[1]

Date range UFS1: December 14, 1901– January 18, 2038, UFS2: 64 bit marked int balance from epoch[1]

Date resolution UFS1 and UFS2: Nanosecond[1]


Upheld working systems A/UX, DragonFlyBSD, FreeBSD, FreeNAS, NAS4Free, HP-UX, NetBSD, NeXTSTEP, Linux, OpenBSD, illumos, Solaris, SunOS, Tru64 UNIX, UNIX System V, and others


A UFS volume is made out of the accompanying parts:

A couple of pieces toward the start of the segment held for boot squares (which must be introduced independently from the filesystem)

A superblock, containing an enchantment number recognizing this as a UFS filesystem, and some other indispensable numbers depicting this current filesystem’s geometry and insights and behavioral tuning parameters

A gathering of chamber gatherings. Every barrel gather has the accompanying segments:

A reinforcement duplicate of the superblock

A barrel aggregate header, with insights, free records, and so forth., about this chamber gathering, like those in the superblock

Various inodes, each containing document characteristics

Various information squares

Inodes are numbered successively, beginning at 0. Inode 0 is held for unallocated catalog passages, inode 1 was the inode of the awful square record in verifiable UNIX forms, trailed by the inode for the root index, which is dependably inode 2 and the inode for the lost+found registry which is inode 3.

Index documents contain just the rundown of filenames in the registry and the inode related with each record. All record metadata are kept in the inode.

History and evolution

Early forms of Unix filesystems were alluded to just as FS. FS just incorporated the boot square, superblock, a cluster of inodes, and the information pieces. This functioned admirably for the little plates early Unixes were intended for, yet as innovation progressed and circles became bigger, moving the head forward and backward between the cluster of inodes and the information squares they alluded to caused whipping. Marshall Kirk McKusick, at that point a Berkeley graduate understudy, upgraded the BSD 4.2’s FFS (Fast File System) by developing chamber gatherings, which split the plate up into littler lumps, with each gathering having its own inodes and information squares.

The purpose of BSD FFS is to endeavor to restrict related information squares and metadata in a similar barrel gathering and, in a perfect world, the greater part of the substance of an index (the two information and metadata for every one of the records) in the same or close-by chamber gathering, in this way lessening discontinuity caused by disseminating a registry’s substance over an entire plate.

A portion of the execution parameters in the superblock included number of tracks and segments, plate turn speed, head speed, and arrangement of the areas between tracks. In a completely advanced framework, the head could be moved between close tracks to peruse scattered areas from substituting tracks while sitting tight for the platter to turn around.

As plates became bigger and bigger, part level enhancement wound up noticeably out of date (particularly with circles that utilized straight division numbering and variable areas per track). With bigger circles and bigger records, divided peruses turned out to be to a greater degree an issue. To battle this, BSD initially expanded the filesystem square size from one segment to 1K out of 4.0BSD; and, in FFS, expanded the filesystem piece estimate from 1K to 8K. This has a few impacts. The odds of a record’s parts being adjoining is considerably more prominent. The measure of overhead to list the record’s pieces is lessened, while the quantity of bytes representable by any given number of squares is expanded.

Bigger circle sizes are additionally conceivable, since the most extreme number of squares is restricted by a settled piece width piece number. Be that as it may, with bigger square sizes, circles with numerous little documents will squander space, since each record must possess no less than one piece. Along these lines, BSD included square level discontinuity, additionally called piece suballocation, tail consolidating, or tail pressing, where the last incomplete piece of information from a few records might be put away in a solitary “part” hinder rather than numerous generally discharge pieces (Allen 2005).


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