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1 | .\" Copyright (c) 1983, 1991, 1993 |
2 | .\" The Regents of the University of California. All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
dc71b7ab | 12 | .\" 3. Neither the name of the University nor the names of its contributors |
984263bc MD |
13 | .\" may be used to endorse or promote products derived from this software |
14 | .\" without specific prior written permission. | |
15 | .\" | |
16 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
17 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
18 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
19 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
20 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
21 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
22 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
23 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
24 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
25 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
26 | .\" SUCH DAMAGE. | |
27 | .\" | |
28 | .\" @(#)tunefs.8 8.2 (Berkeley) 12/11/93 | |
29 | .\" $FreeBSD: src/sbin/tunefs/tunefs.8,v 1.11.2.6 2003/01/23 11:14:02 maxim Exp $ | |
d600454b | 30 | .\" $DragonFly: src/sbin/tunefs/tunefs.8,v 1.3 2006/02/17 19:33:33 swildner Exp $ |
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31 | .\" |
32 | .Dd December 11, 1993 | |
33 | .Dt TUNEFS 8 | |
34 | .Os | |
35 | .Sh NAME | |
36 | .Nm tunefs | |
8895c5fa | 37 | .Nd tune up an existing UFS filesystem |
984263bc MD |
38 | .Sh SYNOPSIS |
39 | .Nm | |
8895c5fa | 40 | .Op Fl \&Ap |
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41 | .Op Fl a Ar maxcontig |
42 | .Op Fl d Ar rotdelay | |
43 | .Op Fl e Ar maxbpg | |
44 | .Op Fl f Ar avgfilesize | |
45 | .Op Fl m Ar minfree | |
46 | .Bk -words | |
8895c5fa TN |
47 | .Op Fl n Cm enable | disable |
48 | .Op Fl o Cm space | time | |
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49 | .Op Fl s Ar avgfpdir |
50 | .Ek | |
8895c5fa | 51 | .Brq Ar special | filesystem |
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52 | .Sh DESCRIPTION |
53 | .Nm Tunefs | |
54 | is designed to change the dynamic parameters of a filesystem | |
55 | which affect the layout policies. | |
56 | The parameters which are to be changed are indicated by the flags | |
57 | given below: | |
58 | .Bl -tag -width indent | |
59 | .It Fl A | |
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60 | The filesystem has several backups of the super-block. |
61 | Specifying | |
984263bc | 62 | this option will cause all backups to be modified as well as the |
8895c5fa TN |
63 | primary super-block. |
64 | This is potentially dangerous - use with caution. | |
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65 | .It Fl a Ar maxcontig |
66 | Specify the maximum number of contiguous blocks that will | |
67 | be laid out before forcing a rotational delay (see | |
68 | .Fl d | |
69 | below). | |
70 | The default value is one, since most device drivers require | |
71 | an interrupt per disk transfer. | |
72 | Device drivers that can chain several buffers together in a single | |
73 | transfer should set this to the maximum chain length. | |
74 | .It Fl d Ar rotdelay | |
75 | Specify the expected time (in milliseconds) | |
76 | to service a transfer completion | |
77 | interrupt and initiate a new transfer on the same disk. | |
78 | It is used to decide how much rotational spacing to place between | |
79 | successive blocks in a file. | |
80 | .It Fl e Ar maxbpg | |
81 | Indicate the maximum number of blocks any single file can | |
82 | allocate out of a cylinder group before it is forced to begin | |
83 | allocating blocks from another cylinder group. | |
84 | Typically this value is set to about one quarter of the total blocks | |
85 | in a cylinder group. | |
86 | The intent is to prevent any single file from using up all the | |
87 | blocks in a single cylinder group, | |
88 | thus degrading access times for all files subsequently allocated | |
89 | in that cylinder group. | |
90 | The effect of this limit is to cause big files to do long seeks | |
91 | more frequently than if they were allowed to allocate all the blocks | |
92 | in a cylinder group before seeking elsewhere. | |
93 | For filesystems with exclusively large files, | |
94 | this parameter should be set higher. | |
95 | .It Fl f Ar avgfilezsize | |
96 | Specify the expected average file size. | |
97 | .It Fl m Ar minfree | |
98 | Specify the percentage of space held back | |
99 | from normal users; the minimum free space threshold. | |
100 | The default value used is 8%. | |
101 | This value can be set to zero, however up to a factor of three | |
102 | in throughput will be lost over the performance obtained at a 10% | |
103 | threshold. | |
104 | Settings of 5% and less force space optimization to | |
105 | always be used which will greatly increase the overhead for file | |
106 | writes. | |
107 | Note that if the value is raised above the current usage level, | |
108 | users will be unable to allocate files until enough files have | |
109 | been deleted to get under the higher threshold. | |
8895c5fa | 110 | .It Fl n Cm enable | disable |
984263bc | 111 | Turn on/off soft updates. |
8895c5fa | 112 | .It Fl o Cm space | time |
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113 | The filesystem can either try to minimize the time spent |
114 | allocating blocks, or it can attempt to minimize the space | |
115 | fragmentation on the disk. | |
116 | Optimization for space has much | |
117 | higher overhead for file writes. | |
118 | The kernel normally changes the preference automatically as | |
119 | the percent fragmentation changes on the filesystem. | |
120 | .It Fl p | |
121 | Show a summary of what the current tunable settings | |
8895c5fa TN |
122 | are on the selected filesystem. |
123 | More detailed information can be | |
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124 | obtained in the |
125 | .Xr dumpfs 8 | |
126 | manual page. | |
127 | .It Fl s Ar avgfpdir | |
128 | Specify the expected number of files per directory. | |
129 | .El | |
130 | .Sh FILES | |
131 | .Bl -tag -width /etc/fstab -compact | |
132 | .It Pa /etc/fstab | |
133 | read this to determine the device file for a | |
134 | specified mount point. | |
135 | .El | |
136 | .Sh SEE ALSO | |
137 | .Xr fs 5 , | |
8895c5fa | 138 | .Xr UFS 5 , |
984263bc MD |
139 | .Xr dumpfs 8 , |
140 | .Xr newfs 8 | |
141 | .Rs | |
142 | .%A M. McKusick | |
143 | .%A W. Joy | |
144 | .%A S. Leffler | |
145 | .%A R. Fabry | |
146 | .%T "A Fast File System for UNIX" | |
147 | .%J "ACM Transactions on Computer Systems 2" | |
148 | .%N 3 | |
149 | .%P pp 181-197 | |
150 | .%D August 1984 | |
151 | .%O "(reprinted in the BSD System Manager's Manual, SMM:5)" | |
152 | .Re | |
d600454b SW |
153 | .Sh HISTORY |
154 | The | |
155 | .Nm | |
156 | command appeared in | |
157 | .Bx 4.2 . | |
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158 | .Sh BUGS |
159 | This program should work on mounted and active filesystems. | |
160 | Because the super-block is not kept in the buffer cache, | |
161 | the changes will only take effect if the program | |
162 | is run on dismounted filesystems. | |
163 | To change the root filesystem, the system must be rebooted | |
164 | after the filesystem is tuned. | |
165 | .\" Take this out and a Unix Demon will dog your steps from now until | |
166 | .\" the time_t's wrap around. | |
167 | .Pp | |
168 | You can tune a filesystem, but you can't tune a fish. |