245 lines
8.4 KiB
Groff
245 lines
8.4 KiB
Groff
.\" Copyright (c) 1983, 1987, 1991 The Regents of the University of California.
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.\" 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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.\" from: @(#)newfs.8 6.10 (Berkeley) 3/16/91
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.\" $Id: newfs.8,v 1.5 1993/08/01 07:38:47 mycroft Exp $
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.\"
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.Dd March 16, 1991
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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 N
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.Op Ar newfs-options
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.Ar special
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.Nm mount_mfs
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.Op Fl F Ar mount_flags
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.Op Ar newfs-options
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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 newfs
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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 device
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basing its defaults on the information in the disk label.
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Typically the defaults are reasonable, however
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.Nm newfs
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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 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 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 newfs .
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The special file 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 Fl
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.It Fl N
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Causes the file system parameters to be printed out
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without really creating the file system.
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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 Fl f Ar frag-size
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The fragment size of the file system in bytes.
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.It Fl m Ar free space \&%
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The percentage of space reserved from normal users; the minimum
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free space threshold. The default value used is 10%.
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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 ``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 10%,
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the default is to optimize for space;
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if the value of minfree greater than or equal to 10%,
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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 a Ar maxcontig
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This specifies the maximum number of contiguous blocks that will
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be laid out before forcing a rotational delay (see
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.Fl d
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below).
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The default value is one.
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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 d Ar rotdelay
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This specifies the expected time (in milliseconds)
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to service a transfer completion
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interrupt and initiate a new transfer on the same disk.
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The default is 4 milliseconds.
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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 e Ar maxbpg
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This indicates 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 i Ar number of bytes per inode
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This specifies the density of inodes in the file system.
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The default is to create an inode for each 2048 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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.It Fl c Ar #cylinders/group
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The number of cylinders per cylinder group in a file system.
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The default value used is 16.
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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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.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 newfs
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to build a file system whose raw image will eventually be used
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on a different type of disk than the one on which it is initially
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created (for example on a write-once disk).
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Note that changing any of these values from their
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defaults will make it impossible for
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.Xr fsck
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to find the alternate superblocks if the standard super block is lost.
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.It Fl r Ar revolutions/minute
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The speed of the disk in revolutions per minute.
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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/track
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The number of sectors per track available for data
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allocation by the file system. This does not
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include sectors reserved at the end of each track
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for bad block replacement (see
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.Fl p
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below).
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.It Fl t Ar #tracks/cylinder
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The number of tracks/cylinder available for data
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allocation by the file system.
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.It Fl p Ar spare sectors per track
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Spare sectors (bad sector replacements) are physical sectors
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that occupy 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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.It Fl x Ar spare sectors per cylinder
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Spare sectors (bad sector replacements) are physical sectors
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that occupy 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
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since they are not available to the file system for data allocation.
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.It Fl l Ar hardware sector interleave
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Used to describe perturbations in the media format to
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compensate for 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
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implies logical sector 0 is separated by one sector from logical
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sector 1.
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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
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compensate for a slow controller.
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Track skew is the offset of sector 0 on track N
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relative to sector 0 on track N-1 on the same cylinder.
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.Pp
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.El
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The following option applies only to
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.Nm mount_mfs .
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.Bl -tag -width Fl
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.It Fl F Ar mount flags
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Used to pass in a decimal numeric value to be passed
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as mount flags when running as a memory based file system.
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This option is primarily intended for use when
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.Nm mount_mfs
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is started by the
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.Xr mount 8
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command.
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.El
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.Sh SEE ALSO
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.Xr disktab 5 ,
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.Xr fs 5 ,
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.Xr disklabel 8 ,
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.Xr diskpart 8 ,
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.Xr fsck 8 ,
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.Xr format 8 ,
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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. 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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