380 lines
12 KiB
Groff
380 lines
12 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 3, 1995
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.Dt NEWFS 8
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.Os BSD 4.2
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.Sh NAME
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.Nm newfs ,
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.Nm mount_mfs
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.Nd construct a new file system
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.Sh SYNOPSIS
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.Nm newfs
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.Op Fl NO
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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 d Ar rotdelay
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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 i Ar bytes
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.Op Fl k Ar skew
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.Op Fl l Ar interleave
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.Op Fl m Ar free space
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.Op Fl n Ar rotational positions
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.Op Fl o Ar optimization
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.Op Fl p Ar sectors
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.Op Fl r Ar revolutions
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.Op Fl s Ar size
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.Op Fl t Ar tracks
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.Op Fl u Ar sectors
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.Op Fl v
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.Op Fl x Ar sectors
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.Ar special
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.Nm mount_mfs
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.Op Fl N
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.Op Fl F Ar file
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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 d Ar rotdelay
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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 i Ar bytes
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.Op Fl m Ar free space
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.Op Fl n Ar rotational positions
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.Op Fl o Ar options
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.Op Fl s Ar size
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.Ar special node
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.Sh DESCRIPTION
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.Nm Newfs
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replaces the more obtuse
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.Xr mkfs 8
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program.
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Before running
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.Nm
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or
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.Nm mount_mfs ,
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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 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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.Nm Mount_mfs
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is used to build a file system in virtual memory and then mount it
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on a specified node.
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.Nm Mount_mfs
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exits and the contents of the file system are lost
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when the file system is unmounted.
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If
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.Nm mount_mfs
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is sent a signal while running,
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for example during system shutdown,
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it will attempt to unmount its
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corresponding file system.
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The parameters to
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.Nm mount_mfs
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are the same as those to
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.Nm Ns .
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If the
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.Fl T
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flag is specified (see below), the special file is unused.
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Otherwise, it is only used to read the disk label which provides
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a set of configuration parameters for the memory based file system.
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The special file is typically that of the primary swap area,
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since that is where the file system will be backed up when
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free memory gets low and the memory supporting
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the file system has to be paged.
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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 and for
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.Nm mount_mfs .
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.It Fl F Ar file
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.Nm Mount_mfs
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will use this file for the image of the filesystem. When
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.Nm mount_mfs
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exits, this file will be left behind.
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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
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Create a
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.Bx 4.3
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format filesystem.
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This options is primarily used to build root filesystems
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that can be understood by older boot ROMs.
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.It Fl T
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Use information for the specified disk from
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.Pa /etc/disktab
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instead of trying to get the information from a disklabel.
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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 (see the
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.Fl d
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option).
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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 file system, in bytes. It must be a power of 2. The
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default size is 8192 bytes, and the smallest allowable size is 4096 bytes.
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.It Fl c Ar #cylinders/group
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The number of cylinders per cylinder group in a file system. The default value
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is 16. The maximum value is dependent on a number of other parameters, in
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particular the block size. The best way to find the maximum value for a
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specific file system is to attempt to specify a value which is far too large:
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.Nm
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will print out the maximum value.
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.It Fl d Ar rotdelay
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This parameter once specified the minimum time in milliseconds required to
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initiate another disk transfer on the same cylinder. It was used in determining
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the rotationally optimal layout for disk blocks within a file. Modern disks
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with read/write-behind achieve higher performance with this feature disabled, so
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this value should be left at the default value of 0 milliseconds. 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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.ne 1i
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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. It must be a power of two
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ranging in value between
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.Ar blocksize/8
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and
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.Ar blocksize .
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The default is 1024 bytes.
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.It Fl i Ar number of bytes per inode
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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 (4 * frag-size) 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 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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.Ao Pa ufs/ffs/fs.h Ac ,
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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 Ar number of distinguished rotational positions
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UFS has the ability to keep track of the availability of blocks at different
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rotational positions, so that it could lay out the data to be picked up with
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minimum rotational latency. This parameter specifies the default number of
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rotational positions to distinguish.
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.Pp
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Nowadays this value should be set to 1 (which essentially disables the
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rotational position table) because modern drives with read-ahead and
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write-behind do better without the rotational position table.
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.It Fl o Ar optimization\ preference
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.Pq ``space'' or ``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 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 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 file system 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 file system).
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.It Fl v
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Specify that the disk does not contain any partitions, and that
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.Nm
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should build a file system on the whole disk.
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This option is useful for synthetic disks such as
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.Nm vinum.
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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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.It Fl k Ar sector \&0 skew , per track
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Used to describe perturbations in the media format to compensate for
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a slow controller.
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Track skew is the offset of sector 0 on track N relative to sector 0
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on track N-1 on the same cylinder.
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This option is of historical importance only; modern controllers are always fast
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enough to handle operations back-to-back.
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.It Fl l Ar hardware sector interleave
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Used to describe perturbations in the media format to compensate for
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a slow controller.
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Interleave is physical sector interleave on each track,
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specified as the denominator of the ratio:
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.Dl sectors read/sectors passed over
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Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies
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logical sector 0 is separated by one sector from logical sector 1.
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This option is of historical importance only; the physical sector layout of
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modern disks is not visible from outside.
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.It Fl p Ar spare sectors per track
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Spare sectors (bad sector replacements) are physical sectors that occupy
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space at the end of each track.
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They are not counted as part of the sectors/track
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.Pq Fl u
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since they are not available to the file system for data allocation.
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This option is of historical importance only. Modern disks perform their own
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bad sector allocation.
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.It Fl r Ar revolutions/minute
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The speed of the disk in revolutions per minute. This value is no longer of
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interest, since all the parameters which depend on it are usually disabled.
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.ne 1i
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.It Fl t Ar #tracks/cylinder
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The number of tracks/cylinder available for data allocation by the file
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system.
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The default is 1.
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If zero is specified, the value from the disklabel will be used.
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.It Fl u Ar sectors/track
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The number of sectors per track 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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This does not include sectors reserved at the end of each track for bad
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block replacement (see the
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.Fl p
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option).
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.It Fl x Ar spare sectors per cylinder
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Spare sectors (bad sector replacements) are physical sectors that occupy
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space at the end of the last track in the cylinder.
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They are deducted from the sectors/track
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.Pq Fl u
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of the last track of each cylinder since they are not available to the file
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system for data allocation.
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This option is of historical importance only. Modern disks perform their own
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bad sector allocation.
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.El
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.Pp
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The options to the
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.Nm mount_mfs
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command are as described for the
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.Nm
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command, except for the
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.Fl o
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option.
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.Pp
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That option is as follows:
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.Bl -tag -width indent
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.It Fl o
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Options are specified with a
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.Fl o
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flag followed by a comma separated string of options.
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See the
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.Xr mount 8
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man page for possible options and their meanings.
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.El
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.Sh EXAMPLES
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.Pp
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.Dl mount_mfs -s 131072 -o nosuid,nodev /dev/da0s1b /tmp
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.Pp
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Mount a 64 MB large memory file system on /tmp, with
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.Xr mount 8
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options nosuid and nodev.
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.Sh BUGS
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The boot code of
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.Fx
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assumes that the file system that carries the
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kernel has blocks of 8 kilobytes and fragments of 1 kilobyte. You will
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not be able to boot from a file system that uses another size.
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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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