.\" Copyright (c) 2001 Networks Associates Technology, Inc.
.\" All rights reserved.
.\"
.\" This software was developed for the FreeBSD Project by Chris
.\" Costello at Safeport Network Services and NAI Labs, the Security
.\" Research Division of Network Associates, Inc. under DARPA/SPAWAR
.\" contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
.\" research program.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" $FreeBSD: src/share/man/man7/ffs.7,v 1.13 2005/07/23 15:09:27 markus Exp $
.\"
.Dd February 17, 2018
.Dt FFS 5
.Os
.Sh NAME
.Nm ffs ,
.Nm ufs
.Nd Berkeley fast file system
.Sh SYNOPSIS
In the kernel configuration file:
.Cd "options FFS"
.Cd "options QUOTA"
.Cd "options SOFTUPDATES"
.Cd "options SUIDDIR"
.Cd "options UFS_DIRHASH"
.Pp
In
.Xr fstab 5 :
.Bd -literal -compact
/dev/disk0a	/mnt ufs rw 1 1
.Ed
.Sh DESCRIPTION
The Berkeley fast file system
provides facilities to store file system data onto a disk device.
.Nm
has been optimized over the years
for speed and reliability
and is the default
.Dx
file system.
.Ss Quotas
.Bl -tag -width 2n
.It Cd "options QUOTA"
This option allows system administrators
to set limits on disk usage
on a per-user basis.
Quotas can be used only on file systems
mounted with the
.Cm quota
option;
see
.Xr quota 1
and
.Xr edquota 8 .
.El
.Ss Soft Updates
.Bl -tag -width 2n
.It Cd "options SOFTUPDATES"
The soft updates feature tracks writes to the disk
and enforces metadata update dependencies
(e.g., updating free block maps)
to ensure that the file system remains consistent.
.Pp
To enable soft updates on an
.Em unmounted
file system, use the following command:
.Pp
.D1 Nm tunefs Fl n Cm enable Ar fs
.Pp
.Ar fs
can be either a mount point listed in
.Xr fstab 5
(e.g.,
.Pa /usr ) ,
or a disk device
(e.g.,
.Pa /dev/da0s0a ) .
.El
.Ss File Ownership Inheritance
.Bl -tag -width 2n
.It Cd "options SUIDDIR"
For use in file sharing environments
on networks including
.Tn "Microsoft Windows"
and
.Tn "Apple Macintosh"
computers,
this option allows files on file systems
mounted with the
.Cm suiddir
option
to inherit the ownership of its directory,
i.e.,
.Dq "if it's my directory, it must be my file."
.El
.Ss Directory Hashing
.Bl -tag -width 2n
.It Cd "options UFS_DIRHASH"
Implements a hash-based lookup scheme for directories
in order to speed up accesses to very large directories.
.El
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
MIBs are defined for use with
.Nm :
.Bl -hang -width ".Va vfs.ufs.dirhash_docheck"
.It Va vfs.ffs.doasyncfree
Asynchronously write out modified i-node and indirect blocks
upon reallocating file system blocks to be contiguous.
(Default: 1.)
.It Va vfs.ffs.doreallocblks
Enable support for the rearrangement of blocks
to be contiguous.
(Default: 1.)
.It Va vfs.ufs.dirhash_docheck
Enable extra sanity tests.
(Default: 0.)
.It Va vfs.ufs.dirhash_mem
Current dirhash memory usage.
.It Va vfs.ufs.dirhash_maxmem
Maximum allowed dirhash memory usage.
.It Va vfs.ufs.dirhash_minsize
Minimum directory size in bytes for which to use hashed lookup.
.El
.Sh SEE ALSO
.Xr quota 1 ,
.Xr edquota 8 ,
.Xr sysctl 8
.Rs
.%A M. McKusick
.%A W. Joy
.%A S. Leffler
.%A R. Fabry
.%D August 1984
.%T "A Fast File System for UNIX"
.%J "ACM Transactions on Computer Systems"
.%N 2
.%V 3
.%P 181-197
.Re
.Rs
.%A M. McKusick
.%D June 2000
.%T "Soft Updates: A Technique for Eliminating Most Synchronous Writes in the Fast Filesystem"
.%J "Proceedings of the Freenix Track at the 1999 Usenix Annual Technical Conference"
.%P 71-84
.Re