1.\" $NetBSD: mount_mfs.8,v 1.4 2002/05/21 11:25:38 lukem Exp $ 2.\" 3.\" Copyright (c) 1983, 1987, 1991, 1993, 1994 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95 35.\" 36.Dd May 21, 2002 37.Dt MOUNT_MFS 8 38.Os 39.Sh NAME 40.Nm mount_mfs 41.Nd mount a memory based file system 42.Sh SYNOPSIS 43.Nm mount_mfs 44.Op Fl N 45.Op Fl a Ar maxcontig 46.Op Fl b Ar block-size 47.Op Fl c Ar cpg 48.Op Fl d Ar rotdelay 49.Op Fl e Ar maxbpg 50.Op Fl f Ar frag-size 51.Op Fl g Ar groupname 52.Op Fl i Ar bytes-per-inode 53.Op Fl m Ar free-space 54.Op Fl n Ar rotational-positions 55.Op Fl o Ar options 56.Op Fl p Ar permissions 57.Op Fl s Ar size 58.Op Fl u Ar username 59.Ar special node 60.Sh DESCRIPTION 61.Nm 62is used to build a file system in virtual memory and then mount it 63on a specified node. 64.Nm 65exits and the contents of the file system are lost 66when the file system is unmounted. 67If 68.Nm 69is sent a signal while running, 70for example during system shutdown, 71it will attempt to unmount its 72corresponding file system. 73.Ar special 74is ignored. 75.Pp 76Options with numeric arguments may contain an optional (case-insensitive) 77suffix: 78.Bl -tag -width 3n -offset indent -compact 79.It b 80Bytes; causes no modification. (Default) 81.It k 82Kilo; multiply the argument by 1024 83.It m 84Mega; multiply the argument by 1048576 85.It g 86Giga; multiply the argument by 1073741824 87.El 88.Pp 89The following options define the general layout policies. 90.Bl -tag -width Fl 91.It Fl N 92Causes the memory file system parameters to be printed out 93without really mounting the memory file system. 94.It Fl a Ar maxcontig 95This specifies the maximum number of contiguous blocks that will be 96laid out before forcing a rotational delay (see the 97.Fl d 98option). 99The default value is 8. 100See 101.Xr tunefs 8 102for more details on how to set this option. 103.It Fl b Ar block-size 104The block size of the file system, in bytes. 105It must be a power of two. 106The smallest allowable size is 4096 bytes. 107The default size depends upon the size of the file system: 108.Pp 109.Bl -tag -width "file system size" -compact -offset indent 110.It Sy "file system size" 111.Ar block-size 112.It \&\*[Lt] 20 MB 1134 KB 114.It \&\*[Lt] 1024 MB 1158 KB 116.It \&\*[Gt]\&= 1024 MB 11716 KB 118.El 119.It Fl c Ar cpg 120The number of cylinders per cylinder group in a file system. 121The default is to compute the maximum allowed by the other parameters. 122This value is dependent on a number of other parameters, in particular 123the block size and the number of bytes per inode. 124.It Fl d Ar rotdelay 125This specifies the expected time (in milliseconds) to service a transfer 126completion interrupt and initiate a new transfer on the same disk. 127The default is 0 milliseconds. 128See 129.Xr tunefs 8 130for more details on how to set this option. 131.ne 1i 132.It Fl e Ar maxbpg 133This indicates the maximum number of blocks any single file can 134allocate out of a cylinder group before it is forced to begin 135allocating blocks from another cylinder group. 136The default is about one quarter of the total blocks in a cylinder group. 137See 138.Xr tunefs 8 139for more details on how to set this option. 140.It Fl f Ar frag-size 141The fragment size of the file system in bytes. 142It must be a power of two ranging in value between 143.Ar block-size Ns /8 144and 145.Ar block-size . 146The optimal 147.Ar block-size Ns : Ns Ar frag-size 148ratio is 8:1. 149Other ratios are possible, but are not recommended, 150and may produce unpredictable results. 151The default size depends upon the size of the file system: 152.Pp 153.Bl -tag -width "file system size" -compact -offset indent 154.It Sy "file system size" 155.Ar frag-size 156.It \&\*[Lt] 20 MB 1570.5 KB 158.It \&\*[Lt] 1024 MB 1591 KB 160.It \&\*[Gt]\&= 1024 MB 1612 KB 162.El 163.It Fl g Ar groupname 164This specifies the group name or group id of the root 165inode of the file system. 166.It Fl i Ar bytes-per-inode 167This specifies the density of inodes in the file system. 168If fewer inodes are desired, a larger number should be used; 169to create more inodes a smaller number should be given. 170The default is to create an inode for every 171.Pq 4 * Ar frag-size 172bytes of data space: 173.Pp 174.Bl -tag -width "file system size" -compact -offset indent 175.It Sy "file system size" 176.Ar bytes-per-inode 177.It \&\*[Lt] 20 MB 1782 KB 179.It \&\*[Lt] 1024 MB 1804 KB 181.It \&\*[Gt]\&= 1024 MB 1828 KB 183.El 184.It Fl m Ar free-space 185The percentage of space reserved from normal users; the minimum free 186space threshold. 187The default value used is 5%. 188See 189.Xr tunefs 8 190for more details on how to set this option. 191.It Fl n Ar rotational-positions 192Determines how many rotational time slots there are in 193one revolution of the disk. 194.It Fl o 195Options are specified with a 196.Fl o 197flag followed by a comma separated string of options. 198See the 199.Xr mount 8 200man page for possible options and their meanings. 201.It Fl p Ar permissions 202This specifies the permissions of the root 203inode of the file system. 204.It Fl s Ar size 205The size of the file system in sectors. 206An 207.Sq s 208suffix will be interpreted as the number of sectors (the default). 209All other suffixes are interpreted as per other numeric arguments, 210except that the number is converted into sectors by dividing by the 211sector size (as specified by 212.Fl S Ar secsize ) 213after suffix interpretation. 214.It Fl u Ar username 215This specifies the user name or user id of the root 216inode of the file system. 217.El 218.Sh NOTES 219The owner and group ids of the root node of the new file system 220are set to the effective uid and gid of the user mounting 221the file system. 222.Sh EXAMPLES 223Mount a 32 MB mfs on /tmp: 224.Pp 225.Dl mount_mfs -s 32m swap /tmp 226.Sh SEE ALSO 227.Xr disktab 5 , 228.Xr fs 5 , 229.Xr disklabel 8 , 230.Xr diskpart 8 , 231.Xr dumpfs 8 , 232.\" .Xr format 8 , 233.Xr fsck_ffs 8 , 234.Xr fsirand 8 , 235.Xr mount 8 , 236.Xr newfs 8 , 237.Xr tunefs 8 238.Rs 239.%A M. McKusick 240.%A W. Joy 241.%A S. Leffler 242.%A R. Fabry 243.%T A Fast File System for UNIX , 244.%J ACM Transactions on Computer Systems 2 245.%V 3 246.%P pp 181-197 247.%D August 1984 248.%O (reprinted in the BSD System Manager's Manual) 249.Re 250.Sh HISTORY 251The 252.Nm 253command appeared in 254.Bx 4.2 . 255