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diff --git a/sbin/tunefs/tunefs.8 b/sbin/tunefs/tunefs.8 new file mode 100644 index 0000000..bfe4cb1 --- /dev/null +++ b/sbin/tunefs/tunefs.8 @@ -0,0 +1,138 @@ +.\" Copyright (c) 1983, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)tunefs.8 8.2 (Berkeley) 12/11/93 +.\" +.Dd December 11, 1993 +.Dt TUNEFS 8 +.Os BSD 4.2 +.Sh NAME +.Nm tunefs +.Nd tune up an existing file system +.Sh SYNOPSIS +.Nm tunefs +.Op Fl a Ar maxcontig +.Op Fl d Ar rotdelay +.Op Fl e Ar maxbpg +.Op Fl m Ar minfree +.Bk -words +.Op Fl o Ar optimize_preference +.Ek +.Op Ar special | Ar filesys +.Sh DESCRIPTION +.Nm Tunefs +is designed to change the dynamic parameters of a file system +which affect the layout policies. +The parameters which are to be changed are indicated by the flags +given below: +.Bl -tag -width Ds +.It Fl a Ar maxcontig +This specifies the maximum number of contiguous blocks that will +be laid out before forcing a rotational delay (see +.Fl d +below). +The default value is one, since most device drivers require +an interrupt per disk transfer. +Device drivers that can chain several buffers together in a single +transfer should set this to the maximum chain length. +.It Fl d Ar rotdelay +This specifies the expected time (in milliseconds) +to service a transfer completion +interrupt and initiate a new transfer on the same disk. +It is used to decide how much rotational spacing to place between +successive blocks in a file. +.It Fl e Ar maxbpg +This indicates the maximum number of blocks any single file can +allocate out of a cylinder group before it is forced to begin +allocating blocks from another cylinder group. +Typically this value is set to about one quarter of the total blocks +in a cylinder group. +The intent is to prevent any single file from using up all the +blocks in a single cylinder group, +thus degrading access times for all files subsequently allocated +in that cylinder group. +The effect of this limit is to cause big files to do long seeks +more frequently than if they were allowed to allocate all the blocks +in a cylinder group before seeking elsewhere. +For file systems with exclusively large files, +this parameter should be set higher. +.It Fl m Ar minfree +This value specifies the percentage of space held back +from normal users; the minimum free space threshold. +The default value used is 10%. +This value can be set to zero, however up to a factor of three +in throughput will be lost over the performance obtained at a 10% +threshold. +Note that if the value is raised above the current usage level, +users will be unable to allocate files until enough files have +been deleted to get under the higher threshold. +.It Fl o Ar optimize_preference +The file system can either try to minimize the time spent +allocating blocks, or it can attempt to minimize the space +fragmentation on the disk. +If the value of minfree (see above) is less than 10%, +then the file system should optimize for space to avoid +running out of full sized blocks. +For values of minfree greater than or equal to 10%, +fragmentation is unlikely to be problematical, and +the file system can be optimized for time. +.El +.Sh SEE ALSO +.Xr fs 5 , +.Xr dumpfs 8 , +.Xr newfs 8 , +.Xr mkfs 8 +.Rs +.%A M. McKusick +.%A W. Joy +.%A S. Leffler +.%A R. Fabry +.%T "A Fast File System for UNIX" +.%J "ACM Transactions on Computer Systems 2" +.%N 3 +.%P pp 181-197 +.%D August 1984 +.%O "(reprinted in the BSD System Manager's Manual, SMM:5)" +.Re +.Sh BUGS +This program should work on mounted and active file systems. +Because the super-block is not kept in the buffer cache, +the changes will only take effect if the program +is run on dismounted file systems. +To change the root file system, the system must be rebooted +after the file system is tuned. +.Pp +You can tune a file system, but you can't tune a fish. +.Sh HISTORY +The +.Nm +command appeared in +.Bx 4.2 . |