xref: /dflybsd-src/share/man/man5/ffs.5 (revision fb3fbfc416acf306a7fae0228cf6c1b6db93ac29)

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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 for
.Pa /boot .
.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