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 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 . 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.It Fl e Ar maxbpg 183Indicate the maximum number of blocks any single file can 184allocate out of a cylinder group before it is forced to begin 185allocating blocks from another cylinder group. 186The default is about one quarter of the total blocks in a cylinder group. 187See 188.Xr tunefs 8 189for more details on how to set this option. 190.It Fl f Ar frag-size 191The fragment size of the file system in bytes. It must be a power of two 192ranging in value between 193.Ar blocksize/8 194and 195.Ar blocksize . 196The default is 1024 bytes. 197.It Fl i Ar number of bytes per inode 198Specify the density of inodes in the file system. 199The default is to create an inode for every (4 * frag-size) bytes of data space. 200If fewer inodes are desired, a larger number should be used; 201to create more inodes a smaller number should be given. 202One inode is required for each distinct file, so this value effectively 203specifies the average file size on the file system. 204.It Fl m Ar free space \&% 205The percentage of space reserved from normal users; the minimum free 206space threshold. 207The default value used is 208defined by 209.Dv MINFREE 210from 211.Ao Pa ufs/ffs/fs.h Ac , 212currently 8%. 213See 214.Xr tunefs 8 215for more details on how to set this option. 216.It Fl n Ar number of distinguished rotational positions 217UFS has the ability to keep track of the availability of blocks at different 218rotational positions, so that it could lay out the data to be picked up with 219minimum rotational latency. This parameter specifies the default number of 220rotational positions to distinguish. 221.Pp 222Nowadays this value should be set to 1 (which essentially disables the 223rotational position table) because modern drives with read-ahead and 224write-behind do better without the rotational position table. 225.It Fl o Ar optimization\ preference 226.Pq ``space'' or ``time'' 227The file system can either be instructed to try to minimize the time spent 228allocating blocks, or to try to minimize the space fragmentation on the disk. 229If the value of minfree (see above) is less than 8%, 230the default is to optimize for space; 231if the value of minfree is greater than or equal to 8%, 232the default is to optimize for time. 233See 234.Xr tunefs 8 235for more details on how to set this option. 236.It Fl s Ar size 237The size of the file system in sectors. This value defaults to the size of the 238raw partition specified in 239.Ar special 240(in other words, 241.Nm 242will use the entire partition for the file system). 243.It Fl v 244Specify that the disk does not contain any partitions, and that 245.Nm 246should build a file system on the whole disk. 247This option is useful for synthetic disks such as 248.Nm vinum . 249.El 250.Pp 251The following options override the standard sizes for the disk geometry. 252Their default values are taken from the disk label. 253Changing these defaults is useful only when using 254.Nm 255to build a file system whose raw image will eventually be used on a 256different type of disk than the one on which it is initially created 257(for example on a write-once disk). 258Note that changing any of these values from their defaults will make 259it impossible for 260.Xr fsck 8 261to find the alternate superblocks if the standard superblock is lost. 262.Bl -tag -width indent 263.It Fl S Ar sector-size 264The size of a sector in bytes (almost never anything but 512). 265.It Fl k Ar sector \&0 skew , per track 266Used to describe perturbations in the media format to compensate for 267a slow controller. 268Track skew is the offset of sector 0 on track N relative to sector 0 269on track N-1 on the same cylinder. 270This option is of historical importance only; modern controllers are always fast 271enough to handle operations back-to-back. 272.It Fl l Ar hardware sector interleave 273Used to describe perturbations in the media format to compensate for 274a slow controller. 275Interleave is physical sector interleave on each track, 276specified as the denominator of the ratio: 277.Dl sectors read/sectors passed over 278Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 279logical sector 0 is separated by one sector from logical sector 1. 280This option is of historical importance only; the physical sector layout of 281modern disks is not visible from outside. 282.It Fl p Ar spare sectors per track 283Spare sectors (bad sector replacements) are physical sectors that occupy 284space at the end of each track. 285They are not counted as part of the sectors/track 286.Pq Fl u 287since they are not available to the file system for data allocation. 288This option is of historical importance only. Modern disks perform their own 289bad sector allocation. 290.It Fl r Ar revolutions/minute 291The speed of the disk in revolutions per minute. This value is no longer of 292interest, since all the parameters which depend on it are usually disabled. 293.It Fl t Ar #tracks/cylinder 294The number of tracks/cylinder available for data allocation by the file 295system. 296The default is 1. 297If zero is specified, the value from the disklabel will be used. 298.It Fl u Ar sectors/track 299The number of sectors per track available for data allocation by the file 300system. 301The default is 4096. 302If zero is specified, the value from the disklabel will be used. 303This does not include sectors reserved at the end of each track for bad 304block replacement (see the 305.Fl p 306option). 307.It Fl x Ar spare sectors per cylinder 308Spare sectors (bad sector replacements) are physical sectors that occupy 309space at the end of the last track in the cylinder. 310They are deducted from the sectors/track 311.Pq Fl u 312of the last track of each cylinder since they are not available to the file 313system for data allocation. 314This option is of historical importance only. Modern disks perform their own 315bad sector allocation. 316.El 317.Pp 318The options to the 319.Nm mount_mfs 320command are as described for the 321.Nm 322command, except for the 323.Fl o 324option. 325.Pp 326That option is as follows: 327.Bl -tag -width indent 328.It Fl o 329Options are specified with a 330.Fl o 331flag followed by a comma separated string of options. 332See the 333.Xr mount 8 334man page for possible options and their meanings. 335.El 336.Sh EXAMPLES 337.Pp 338.Dl mount_mfs -s 131072 -o nosuid,nodev /dev/da0s1b /tmp 339.Pp 340Mount a 64 MB large memory file system on /tmp, with 341.Xr mount 8 342options nosuid and nodev. 343.Sh BUGS 344The boot code of 345.Fx 346assumes that the file system that carries the 347kernel has blocks of 8 kilobytes and fragments of 1 kilobyte. 348You will 349not be able to boot from a file system that uses another size. 350.Sh SEE ALSO 351.Xr fdformat 1 , 352.Xr disktab 5 , 353.Xr fs 5 , 354.Xr camcontrol 8 , 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