77edab906e
We need to parse the arguments first, then open the device (if specified) and then apply the changes. This change will disallow the (undocumented) use of multiple instances of the same argument on the same command line for the sack of a better error message. Other changes are: 1) the softupdates (-n) now issue a warning about remaining unchanged 2) the usage and man page is changed to specify "space | time" instead of "optimization preference". PR: bin/23335 Submitted by:Mark Peek <mark@whistle.com>
181 lines
6.4 KiB
Groff
181 lines
6.4 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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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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.\" @(#)tunefs.8 8.2 (Berkeley) 12/11/93
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.\" $FreeBSD$
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.\"
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.Dd December 11, 1993
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.Dt TUNEFS 8
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.Os BSD 4.2
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.Sh NAME
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.Nm tunefs
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.Nd tune up an existing file system
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.Sh SYNOPSIS
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.Nm
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.Op Fl A
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.Op Fl a Ar maxcontig
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.Op Fl d Ar rotdelay
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.Op Fl e Ar maxbpg
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.Op Fl m Ar minfree
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.Bk -words
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.Op Fl n Ar enable | disable
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.Op Fl o Ar space | time
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.Op Fl p
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.Ek
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.Ar special | Ar filesystem
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.Sh DESCRIPTION
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.Nm Tunefs
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is designed to change the dynamic parameters of a file system
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which affect the layout policies.
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The parameters which are to be changed are indicated by the flags
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given below:
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.Bl -tag -width indent
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.It Fl A
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The file system has several backups of the super-block. Specifying
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this option will cause all backups to be modified as well as the
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primary super-block. This is potentially dangerous - use with caution.
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.It Fl a Ar maxcontig
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Specify 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, since most device drivers require
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an interrupt per disk transfer.
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Device drivers that can chain several buffers together in a single
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transfer should set this to the maximum chain length.
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.It Fl d Ar rotdelay
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Specify 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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It is used to decide how much rotational spacing to place between
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successive blocks in a file.
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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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Typically this value is set to about one quarter of the total blocks
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in a cylinder group.
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The intent is to prevent any single file from using up all the
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blocks in a single cylinder group,
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thus degrading access times for all files subsequently allocated
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in that cylinder group.
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The effect of this limit is to cause big files to do long seeks
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more frequently than if they were allowed to allocate all the blocks
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in a cylinder group before seeking elsewhere.
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For file systems with exclusively large files,
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this parameter should be set higher.
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.It Fl m Ar minfree
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Specify the percentage of space held back
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from normal users; the minimum free space threshold.
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The default value used is 8%.
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This value can be set to zero, however up to a factor of three
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in throughput will be lost over the performance obtained at a 10%
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threshold.
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Settings of 5% and less force space optimization to
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always be used which will greatly increase the overhead for file
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writes.
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Note that if the value is raised above the current usage level,
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users will be unable to allocate files until enough files have
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been deleted to get under the higher threshold.
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.It Fl n Ar enable | disable
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Turn on/off soft updates.
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An unmounted filesystem is required.
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.It Fl o Ar space | time
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The file system can either try to minimize the time spent
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allocating blocks, or it can attempt to minimize the space
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fragmentation on the disk.
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Optimization for space has much
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higher overhead for file writes.
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The kernel normally changes the preference automatically as
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the percent fragmentation changes on the file system.
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.It Fl p
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Show a summary of what the current tunable settings
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are on the selected file system. More detailed information can be
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obtained in the
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.Xr dumpfs 8
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manual page.
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.El
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.Pp
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At least one of the above flags is required.
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.Sh ERRORS
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If
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.Nm
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.Fl n
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is run to enable/disable soft update on an unmounted file system
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after booting single-user then
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.Nm
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will output the warning
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.Pp
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reload\&: Invalid argument
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.Pp
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preceded by the raw device name.
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This occurs because the filesystem
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is not currently mounted read-only.
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.Nm
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is trying to reload the incore (r*) device, but it was never loaded
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to begin with.
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When you boot single user, only
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.Dq /
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is mounted, so all other filesystems will give you that warning.
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It is completely harmless.
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.Sh SEE ALSO
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.Xr fs 5 ,
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.Xr dumpfs 8 ,
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.Xr newfs 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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.%N 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, SMM:5)"
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.Re
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.Sh BUGS
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This program should work on mounted and active file systems.
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Because the super-block is not kept in the buffer cache,
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the changes will only take effect if the program
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is run on dismounted file systems.
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To change the root file system, the system must be rebooted
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after the file system is tuned.
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.\" Take this out and a Unix Demon will dog your steps from now until
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.\" the time_t's wrap around.
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.Pp
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You can tune a file system, but you can't tune a fish.
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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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