1.\" Copyright (c) 1983, 1987, 1991, 1993, 1994 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. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95 33.\" $FreeBSD$ 34.\" 35.Dd May 3, 1995 36.Dt NEWFS 8 37.Os BSD 4.2 38.Sh NAME 39.Nm newfs , 40.Nm mount_mfs 41.Nd construct a new file system 42.Sh SYNOPSIS 43.Nm newfs 44.Op Fl NO 45.Op Fl S Ar sector-size 46.Op Fl T Ar disktype 47.Op Fl a Ar maxcontig 48.Op Fl b Ar block-size 49.Op Fl c Ar cylinders 50.Op Fl d Ar rotdelay 51.Op Fl e Ar maxbpg 52.Op Fl f Ar frag-size 53.Op Fl i Ar bytes 54.Op Fl k Ar skew 55.Op Fl l Ar interleave 56.Op Fl m Ar free space 57.Op Fl n Ar rotational positions 58.Op Fl o Ar optimization 59.Op Fl p Ar sectors 60.Op Fl r Ar revolutions 61.Op Fl s Ar size 62.Op Fl t Ar tracks 63.Op Fl u Ar sectors 64.Op Fl v 65.Op Fl x Ar sectors 66.Ar special 67.Nm mount_mfs 68.Op Fl N 69.Op Fl F Ar file 70.Op Fl T Ar disktype 71.Op Fl a Ar maxcontig 72.Op Fl b Ar block-size 73.Op Fl c Ar cylinders 74.Op Fl d Ar rotdelay 75.Op Fl e Ar maxbpg 76.Op Fl f Ar frag-size 77.Op Fl i Ar bytes 78.Op Fl m Ar free space 79.Op Fl n Ar rotational positions 80.Op Fl o Ar options 81.Op Fl s Ar size 82.Ar special node 83.Sh DESCRIPTION 84.Nm Newfs 85replaces the more obtuse 86.Xr mkfs 8 87program. 88Before running 89.Nm 90or 91.Nm mount_mfs , 92the disk must be labeled using 93.Xr disklabel 8 . 94.Nm Newfs 95builds a file system on the specified special file. 96(We often refer to the 97.Dq special file 98as the 99.Dq disk , 100although the special file need not be a physical disk. 101In fact, it need not even be special.) 102Typically the defaults are reasonable, however 103.Nm 104has numerous options to allow the defaults to be selectively overridden. 105.Pp 106.Nm Mount_mfs 107is used to build a file system in virtual memory and then mount it 108on a specified node. 109.Nm Mount_mfs 110exits and the contents of the file system are lost 111when the file system is unmounted. 112If 113.Nm mount_mfs 114is sent a signal while running, 115for example during system shutdown, 116it will attempt to unmount its 117corresponding file system. 118The parameters to 119.Nm mount_mfs 120are the same as those to 121.Nm Ns . 122If the 123.Fl T 124flag is specified (see below), the special file is unused. 125Otherwise, it is only used to read the disk label which provides 126a set of configuration parameters for the memory based file system. 127The special file is typically that of the primary swap area, 128since that is where the file system will be backed up when 129free memory gets low and the memory supporting 130the file system has to be paged. 131.Pp 132The following options define the general layout policies: 133.Bl -tag -width indent 134.It Fl T Ar disktype 135For backward compatibility and for 136.Nm mount_mfs . 137.It Fl F Ar file 138.Nm Mount_mfs 139will use this file for the image of the filesystem. When 140.Nm mount_mfs 141exits, this file will be left behind. 142.It Fl N 143Cause the file system parameters to be printed out 144without really creating the file system. 145.It Fl O 146Create a 147.Bx 4.3 148format filesystem. 149This options is primarily used to build root filesystems 150that can be understood by older boot ROMs. 151.It Fl T 152Use information for the specified disk from 153.Pa /etc/disktab 154instead of trying to get the information from a disklabel. 155.It Fl a Ar maxcontig 156Specify the maximum number of contiguous blocks that will be 157laid out before forcing a rotational delay (see the 158.Fl d 159option). 160The default value is 1. 161See 162.Xr tunefs 8 163for more details on how to set this option. 164.It Fl b Ar block-size 165The block size of the file system, in bytes. It must be a power of 2. The 166default size is 8192 bytes, and the smallest allowable size is 4096 bytes. 167.It Fl c Ar #cylinders/group 168The number of cylinders per cylinder group in a file system. The default value 169is 16. The maximum value is dependent on a number of other parameters, in 170particular the block size. The best way to find the maximum value for a 171specific file system is to attempt to specify a value which is far too large: 172.Nm 173will print out the maximum value. 174.It Fl d Ar rotdelay 175This parameter once specified the minimum time in milliseconds required to 176initiate another disk transfer on the same cylinder. It was used in determining 177the rotationally optimal layout for disk blocks within a file. Modern disks 178with read/write-behind achieve higher performance with this feature disabled, so 179this value should be left at the default value of 0 milliseconds. See 180.Xr tunefs 8 181for more details on how to set this option. 182.ne 1i 183.It Fl e Ar maxbpg 184Indicate the maximum number of blocks any single file can 185allocate out of a cylinder group before it is forced to begin 186allocating blocks from another cylinder group. 187The default is about one quarter of the total blocks in a cylinder group. 188See 189.Xr tunefs 8 190for more details on how to set this option. 191.It Fl f Ar frag-size 192The fragment size of the file system in bytes. It must be a power of two 193ranging in value between 194.Ar blocksize/8 195and 196.Ar blocksize . 197The default is 1024 bytes. 198.It Fl i Ar number of bytes per inode 199Specify the density of inodes in the file system. 200The default is to create an inode for every (4 * frag-size) bytes of data space. 201If fewer inodes are desired, a larger number should be used; 202to create more inodes a smaller number should be given. 203One inode is required for each distinct file, so this value effectively 204specifies the average file size on the file system. 205.It Fl m Ar free space \&% 206The percentage of space reserved from normal users; the minimum free 207space threshold. 208The default value used is 209defined by 210.Dv MINFREE 211from 212.Ao Pa ufs/ffs/fs.h Ac , 213currently 8%. 214See 215.Xr tunefs 8 216for more details on how to set this option. 217.It Fl n Ar number of distinguished rotational positions 218UFS has the ability to keep track of the availability of blocks at different 219rotational positions, so that it could lay out the data to be picked up with 220minimum rotational latency. This parameter specifies the default number of 221rotational positions to distinguish. 222.Pp 223Nowadays this value should be set to 1 (which essentially disables the 224rotational position table) because modern drives with read-ahead and 225write-behind do better without the rotational position table. 226.It Fl o Ar optimization\ preference 227.Pq ``space'' or ``time'' 228The file system can either be instructed to try to minimize the time spent 229allocating blocks, or to try to minimize the space fragmentation on the disk. 230If the value of minfree (see above) is less than 8%, 231the default is to optimize for space; 232if the value of minfree is greater than or equal to 8%, 233the default is to optimize for time. 234See 235.Xr tunefs 8 236for more details on how to set this option. 237.It Fl s Ar size 238The size of the file system in sectors. This value defaults to the size of the 239raw partition specified in 240.Ar special 241(in other words, 242.Nm 243will use the entire partition for the file system). 244.It Fl v 245Specify that the disk does not contain any partitions, and that 246.Nm 247should build a file system on the whole disk. 248This option is useful for synthetic disks such as 249.Nm vinum. 250.El 251.Pp 252The following options override the standard sizes for the disk geometry. 253Their default values are taken from the disk label. 254Changing these defaults is useful only when using 255.Nm 256to build a file system whose raw image will eventually be used on a 257different type of disk than the one on which it is initially created 258(for example on a write-once disk). 259Note that changing any of these values from their defaults will make 260it impossible for 261.Xr fsck 8 262to find the alternate superblocks if the standard superblock is lost. 263.Bl -tag -width indent 264.It Fl S Ar sector-size 265The size of a sector in bytes (almost never anything but 512). 266.It Fl k Ar sector \&0 skew , per track 267Used to describe perturbations in the media format to compensate for 268a slow controller. 269Track skew is the offset of sector 0 on track N relative to sector 0 270on track N-1 on the same cylinder. 271This option is of historical importance only; modern controllers are always fast 272enough to handle operations back-to-back. 273.It Fl l Ar hardware sector interleave 274Used to describe perturbations in the media format to compensate for 275a slow controller. 276Interleave is physical sector interleave on each track, 277specified as the denominator of the ratio: 278.Dl sectors read/sectors passed over 279Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 280logical sector 0 is separated by one sector from logical sector 1. 281This option is of historical importance only; the physical sector layout of 282modern disks is not visible from outside. 283.It Fl p Ar spare sectors per track 284Spare sectors (bad sector replacements) are physical sectors that occupy 285space at the end of each track. 286They are not counted as part of the sectors/track 287.Pq Fl u 288since they are not available to the file system for data allocation. 289This option is of historical importance only. Modern disks perform their own 290bad sector allocation. 291.It Fl r Ar revolutions/minute 292The speed of the disk in revolutions per minute. This value is no longer of 293interest, since all the parameters which depend on it are usually disabled. 294.ne 1i 295.It Fl t Ar #tracks/cylinder 296The number of tracks/cylinder available for data allocation by the file 297system. 298The default is 1. 299If zero is specified, the value from the disklabel will be used. 300.It Fl u Ar sectors/track 301The number of sectors per track available for data allocation by the file 302system. 303The default is 4096. 304If zero is specified, the value from the disklabel will be used. 305This does not include sectors reserved at the end of each track for bad 306block replacement (see the 307.Fl p 308option). 309.It Fl x Ar spare sectors per cylinder 310Spare sectors (bad sector replacements) are physical sectors that occupy 311space at the end of the last track in the cylinder. 312They are deducted from the sectors/track 313.Pq Fl u 314of the last track of each cylinder since they are not available to the file 315system for data allocation. 316This option is of historical importance only. Modern disks perform their own 317bad sector allocation. 318.El 319.Pp 320The options to the 321.Nm mount_mfs 322command are as described for the 323.Nm 324command, except for the 325.Fl o 326option. 327.Pp 328That option is as follows: 329.Bl -tag -width indent 330.It Fl o 331Options are specified with a 332.Fl o 333flag followed by a comma separated string of options. 334See the 335.Xr mount 8 336man page for possible options and their meanings. 337.El 338.Sh EXAMPLES 339.Pp 340.Dl mount_mfs -s 131072 -o nosuid,nodev /dev/da0s1b /tmp 341.Pp 342Mount a 64 MB large memory file system on /tmp, with 343.Xr mount 8 344options nosuid and nodev. 345.Sh BUGS 346The boot code of 347.Bx Free 348assumes that the file system that carries the 349kernel has blocks of 8 kilobytes and fragments of 1 kilobyte. You will 350not be able to boot from a file system that uses another size. 351.Sh SEE ALSO 352.Xr fdformat 1 , 353.Xr disktab 5 , 354.Xr fs 5 , 355.Xr disklabel 8 , 356.Xr diskpart 8 , 357.Xr dumpfs 8 , 358.Xr fsck 8 , 359.Xr mount 8 , 360.Xr tunefs 8 , 361.Xr vinum 8 362.Rs 363.%A M. McKusick 364.%A W. Joy 365.%A S. Leffler 366.%A R. Fabry 367.%T A Fast File System for UNIX , 368.%J ACM Transactions on Computer Systems 2 369.%V 3 370.%P pp 181-197 371.%D August 1984 372.%O (reprinted in the BSD System Manager's Manual) 373.Re 374.Sh HISTORY 375The 376.Nm 377command appeared in 378.Bx 4.2 . 379