2001-12-27 03:05:44 +00:00
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.\" Copyright (c) 2001 Networks Associates Technologies, Inc.
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.\" All rights reserved.
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.\"
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.\" This software was developed for the FreeBSD Project by Chris
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.\" Costello at Safeport Network Services and NAI Labs, the Security
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.\" Research Division of Network Associates, Inc. under DARPA/SPAWAR
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.\" contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
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.\" research program.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote
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.\" products derived from this software without specific prior written
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.\" permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.Dd December 26, 2001
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.Dt FFS 4
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.Sh NAME
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.Nm ffs
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.Nd Berkeley fast file system
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.Sh SYNOPSIS
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.Cd options FFS
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.Cd options SOFTUPDATES
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.Sh DESCRIPTION
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The Berkeley fast file system
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provides facilities to store file system data onto a disk device.
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.Nm FFS
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has been optimized over the years
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for speed and reliability
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and is the basis for the
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.Xr ufs 4
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file system.
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.Pp
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The
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.Dv SOFTUPDATES
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option is used to enable soft updates.
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The soft updates feature tracks writes to the disk
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and enforces metadata update dependancies
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(e.g. updating free block maps)
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to ensure that the file system remains consistent.
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To enable this feature,
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add the following to your kernel configuration file:
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.Pp
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.Dl Cd options SOFTUPDATES
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.Pp
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To enable soft updates on an
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.Em unmounted
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file system, use the following command:
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.Pp
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.Dl Ic tunefs -n enable Sy /foo
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.Pp
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.Dq Sy foo
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2001-12-30 03:47:06 +00:00
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can be either a mount point listed in
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.Pa /etc/fstab
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2001-12-27 03:05:44 +00:00
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(e.g.
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.Pa /usr ) ,
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or a disk device
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(e.g.
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.Pa /dev/da0s1a ) .
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.Pp
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The following
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.Xr sysctl 8
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MIBs are defined for use with
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.Nm FFS :
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.Bl -hang -width "vfs.ffs.doreallocblk"
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.It Em vfs.ffs.doasyncfree
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Asynchronously write out modified inode and indirect blocks
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upon reallocating file system blocks to be contiguous.
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(Default: 1.)
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.It Em vfs.ffs.doreallocblks
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Enable support for the rearrangement of blocks
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to be contiguous.
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(Default: 1.)
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.El
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.Sh SEE ALSO
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.Xr ufs 4 ,
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.Xr tunefs 8
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.Rs
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.%A M. McKusick
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.%A W. Joy
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.%A S. Lefler
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.%A R. Fabry
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.%D August 1984
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.%T "A Fast File System for UNIX"
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.%J "ACM Transactions on Computer Systems"
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.%N 2
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.%V 3
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.%P 181-197
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.Re
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.Rs
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.%A M. McKusick
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.%D June 2000
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.%T "Soft Updates: A Technique for Eliminating Most Synchronous Writes in the Fast Filesystem"
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.%J "Proceedings of the Freenix Track at the 1999 Usenix Annual Technical Conference"
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.%P 71-84
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.Re
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