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want to prepare disk images for emulators (though 'makefs' in port can do something similar). This relies on: + minor changes to pass the consistency checks even when working on a file; + an additional option, '-p partition' , to specify the disk partition to initialize; + some changes on the I/O routines to deal with partition offsets. The latter was a bit tricky to implement, see the details in newfs.h: in newfs, I/O is done through libufs which assumes that the file descriptor refers to the whole partition. Introducing support for the offset in libufs would require a non-backward compatible change in the library, to be dealt with a version bump or with symbol versioning. I felt both approaches to be overkill for this specific application, especially because there might be other changes to libufs that might become necessary in the near future. So I used the following trick: - read access is always done by calling bread() directly, so we just add the offset in the (few) places that call bread(); - write access is done through bwrite() and sbwrite(), which in turn calls bwrite(). To avoid rewriting sbwrite(), we supply our own version of bwrite() here, which takes precedence over the version in libufs. MFC after: 4 weeks
301 lines
9.2 KiB
Groff
301 lines
9.2 KiB
Groff
.\" Copyright (c) 1983, 1987, 1991, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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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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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95
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.\" $FreeBSD$
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.\"
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.Dd March 21, 2008
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.Dt NEWFS 8
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.Os
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.Sh NAME
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.Nm newfs
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.Nd construct a new UFS1/UFS2 file system
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.Sh SYNOPSIS
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.Nm
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.Op Fl EJNUln
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.Op Fl L Ar volname
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.Op Fl O Ar filesystem-type
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.Op Fl S Ar sector-size
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.Op Fl T Ar disktype
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.Op Fl a Ar maxcontig
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.Op Fl b Ar block-size
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.Op Fl c Ar blocks-per-cylinder-group
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.Op Fl d Ar max-extent-size
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.Op Fl e Ar maxbpg
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.Op Fl f Ar frag-size
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.Op Fl g Ar avgfilesize
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.Op Fl h Ar avgfpdir
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.Op Fl i Ar bytes
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.Op Fl m Ar free-space
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.Op Fl o Ar optimization
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.Op Fl p Ar partition
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.Op Fl r Ar reserved
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.Op Fl s Ar size
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.Ar special
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.Sh DESCRIPTION
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The
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.Nm
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utility is used to initialize and clear file systems before first use.
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The
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.Nm
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utility builds a file system on the specified special file.
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(We often refer to the
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.Dq special file
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as the
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.Dq disk ,
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although the special file need not be a physical disk.
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In fact, it need not even be special.)
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Typically the defaults are reasonable, however
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.Nm
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has numerous options to allow the defaults to be selectively overridden.
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.Pp
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The following options define the general layout policies:
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.Bl -tag -width indent
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.It Fl E
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Erase the content of the disk before making the filesystem.
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The reserved area in front of the superblock (for bootcode) will not be erased.
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This is a relevant option for flash based storage devices that use
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wear levelling algorithms.
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NB: Erasing may take as long time as writing every sector on the disk.
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.It Fl J
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Enable journaling on the new file system via gjournal.
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.It Fl L Ar volname
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Add a volume label to the new file system.
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.It Fl N
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Cause the file system parameters to be printed out
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without really creating the file system.
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.It Fl O Ar filesystem-type
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Use 1 to specify that a UFS1 format file system be built;
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use 2 to specify that a UFS2 format file system be built.
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The default format is UFS2.
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.It Fl T Ar disktype
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For backward compatibility.
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.It Fl U
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Enable soft updates on the new file system.
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.It Fl a Ar maxcontig
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Specify the maximum number of contiguous blocks that will be
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laid out before forcing a rotational delay.
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The default value is 16.
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See
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.Xr tunefs 8
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for more details on how to set this option.
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.It Fl b Ar block-size
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The block size of the file system, in bytes.
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It must be a power of 2.
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The
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default size is 16384 bytes, and the smallest allowable size is 4096 bytes.
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The optimal block:fragment ratio is 8:1.
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Other ratios are possible, but are not recommended,
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and may produce poor results.
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.It Fl c Ar blocks-per-cylinder-group
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The number of blocks per cylinder group in a file system.
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The default is to compute the maximum allowed by the other parameters.
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This value is
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dependent on a number of other parameters, in particular the block size
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and the number of bytes per inode.
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.It Fl d Ar max-extent-size
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The file system may choose to store large files using extents.
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This parameter specifies the largest extent size that may be used.
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It is presently limited to its default value which is 16 times
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the file system blocksize.
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.It Fl e Ar maxbpg
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Indicate the maximum number of blocks any single file can
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allocate out of a cylinder group before it is forced to begin
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allocating blocks from another cylinder group.
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The default is about one quarter of the total blocks in a cylinder group.
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See
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.Xr tunefs 8
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for more details on how to set this option.
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.It Fl f Ar frag-size
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The fragment size of the file system in bytes.
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It must be a power of two
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ranging in value between
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.Ar blocksize Ns /8
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and
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.Ar blocksize .
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The default is 2048 bytes.
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.It Fl g Ar avgfilesize
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The expected average file size for the file system.
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.It Fl h Ar avgfpdir
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The expected average number of files per directory on the file system.
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.It Fl i Ar bytes
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Specify the density of inodes in the file system.
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The default is to create an inode for every
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.Pq 4 * Ar frag-size
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bytes of data space.
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If fewer inodes are desired, a larger number should be used;
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to create more inodes a smaller number should be given.
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One inode is required for each distinct file, so this value effectively
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specifies the average file size on the file system.
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.It Fl l
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Enable multilabel MAC on the new file system.
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.It Fl m Ar free-space
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The percentage of space reserved from normal users; the minimum free
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space threshold.
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The default value used is
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defined by
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.Dv MINFREE
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from
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.In ufs/ffs/fs.h ,
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currently 8%.
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See
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.Xr tunefs 8
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for more details on how to set this option.
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.It Fl n
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Do not create a
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.Pa .snap
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directory on the new file system.
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The resulting file system will not support snapshot generation, so
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.Xr dump 8
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in live mode and background
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.Xr fsck 8
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will not function properly.
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The traditional
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.Xr fsck 8
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and offline
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.Xr dump 8
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will work on the file system.
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This option is intended primarily for memory or vnode-backed file systems that
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do not require
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.Xr dump 8
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or
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.Xr fsck 8
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support.
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.It Fl o Ar optimization
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.Cm ( space
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or
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.Cm time ) .
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The file system can either be instructed to try to minimize the time spent
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allocating blocks, or to try to minimize the space fragmentation on the disk.
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If the value of minfree (see above) is less than 8%,
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the default is to optimize for
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.Cm space ;
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if the value of minfree is greater than or equal to 8%,
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the default is to optimize for
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.Cm time .
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See
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.Xr tunefs 8
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for more details on how to set this option.
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.It Fl p Ar partition
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The partition name (a..h) you want to use in case the underlying image
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is a file, so you don't have access to individual partitions through the
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filesystem.
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Can also be used with a device, e.g.
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.Nm
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.Fl p Ar f
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.Ar /dev/da1s3
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is equivalent to
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.Nm
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.Ar /dev/da1s3f .
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.It Fl r Ar reserved
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The size, in sectors, of reserved space
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at the end of the partition specified in
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.Ar special .
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This space will not be occupied by the file system;
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it can be used by other consumers such as
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.Xr geom 4 .
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Defaults to 0.
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.It Fl s Ar size
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The size of the file system in sectors.
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This value defaults to the size of the
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raw partition specified in
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.Ar special
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less the
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.Ar reserved
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space at its end (see
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.Fl r ) .
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A
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.Ar size
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of 0 can also be used to choose the default value.
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A valid
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.Ar size
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value cannot be larger than the default one,
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which means that the file system cannot extend into the reserved space.
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.El
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.Pp
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The following options override the standard sizes for the disk geometry.
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Their default values are taken from the disk label.
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Changing these defaults is useful only when using
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.Nm
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to build a file system whose raw image will eventually be used on a
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different type of disk than the one on which it is initially created
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(for example on a write-once disk).
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Note that changing any of these values from their defaults will make
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it impossible for
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.Xr fsck 8
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to find the alternate superblocks if the standard superblock is lost.
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.Bl -tag -width indent
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.It Fl S Ar sector-size
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The size of a sector in bytes (almost never anything but 512).
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.El
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.Sh EXAMPLES
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.Dl newfs /dev/ad3s1a
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.Pp
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Creates a new ufs file system on
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.Pa ad3s1a .
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The
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.Nm
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utility will use a block size of 16384 bytes, a fragment size of 2048 bytes
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and the largest possible number of blocks per cylinders group.
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These values tend to produce better performance for most applications
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than the historical defaults
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(8192 byte block size and 1024 byte fragment size).
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This large fragment size may lead to much wasted space
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on file systems that contain many small files.
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.Sh SEE ALSO
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.Xr fdformat 1 ,
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.Xr geom 4 ,
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.Xr disktab 5 ,
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.Xr fs 5 ,
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.Xr bsdlabel 8 ,
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.Xr camcontrol 8 ,
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.Xr dump 8 ,
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.Xr dumpfs 8 ,
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.Xr fsck 8 ,
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.Xr mount 8 ,
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.Xr tunefs 8 ,
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.Xr gvinum 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. Leffler
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.%A R. Fabry
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.%T A Fast File System for UNIX
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.%J ACM Transactions on Computer Systems 2
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.%V 3
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.%P pp 181-197
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.%D August 1984
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.%O (reprinted in the BSD System Manager's Manual)
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.Re
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.2 .
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