230 lines
7.6 KiB
Groff
230 lines
7.6 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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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 May 29, 2001
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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 filesystem
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.Sh SYNOPSIS
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.Nm
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.Op Fl NOU
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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 cylinders
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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 avfpdir
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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 s Ar size
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.Op Fl u Ar sectors
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.Ar special
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.Sh DESCRIPTION
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.Nm Newfs
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is used to initialize and clear filesystems before first use.
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Before running
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.Nm
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the disk must be labeled using
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.Xr disklabel 8 .
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.Nm Newfs
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builds a filesystem 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 T Ar disktype
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For backward compatibility.
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.It Fl N
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Cause the filesystem parameters to be printed out
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without really creating the filesystem.
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.It Fl U
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Enables soft updates on the new filesystem.
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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 1.
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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 filesystem, in bytes. It must be a power of 2. 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 unpredictable results.
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.It Fl c Ar #cylinders/group
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The number of cylinders per cylinder group in a filesystem. The default
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is to compute the maximum allowed by the other parameters. 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 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 filesystem in bytes. 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 filesystem.
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.It Fl h Ar avgfpdir
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The expected average number of files per directory on the filesystem.
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.It Fl i Ar number of bytes per inode
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Specify the density of inodes in the filesystem.
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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 filesystem.
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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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.Aq Pa 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 o Ar optimization\ preference
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.Pq Ar space No or Ar time .
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The filesystem 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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.Ar 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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.Ar 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 s Ar size
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The size of the filesystem in sectors. 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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(in other words,
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.Nm
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will use the entire partition for the filesystem).
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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 filesystem 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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.It Fl u Ar sectors/cylinders
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The number of sectors per cylinder available for data allocation by the file
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system.
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The default is 4096.
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If zero is specified, the value from the disklabel will be used.
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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 filesystem on
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.Pa ad3s1a .
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.Nm
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will use a block size of 16384 bytes, a fragment size of 2048 bytes
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and the largest possible number of cylinders per 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
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may lead to large amounts of wasted space
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on filesystems that contain a large number of small files.
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.Sh SEE ALSO
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.Xr fdformat 1 ,
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.Xr disktab 5 ,
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.Xr fs 5 ,
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.Xr camcontrol 8 ,
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.Xr disklabel 8 ,
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.Xr diskpart 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 vinum 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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command appeared in
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.Bx 4.2 .
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