1.\" Copyright (c) 1983, 1987, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)newfs.8 8.4 (Berkeley) 06/01/94 7.\" 8.Dd 9.Dt NEWFS 8 10.Os BSD 4.2 11.Sh NAME 12.Nm newfs , 13.Nm mfs 14.Nd construct a new file system 15.Sh SYNOPSIS 16.Nm newfs 17.Op Fl NO 18.Op Fl S Ar sector-size 19.Op Fl a maxcontig 20.Op Fl b Ar block-size 21.Op Fl c Ar cylinders 22.Op Fl d Ar rotdelay 23.Op Fl e Ar maxbpg 24.Op Fl f Ar frag-size 25.Op Fl i Ar bytes 26.Op Fl k Ar skew 27.Op Fl l Ar interleave 28.Op Fl m Ar free space 29.Op Fl o Ar optimization 30.Op Fl p Ar sectors 31.Op Fl r Ar revolutions 32.Op Fl s Ar size 33.Op Fl t Ar tracks 34.Op Fl u Ar sectors 35.Op Fl x Ar sectors 36.Ar special 37.Nm mount_mfs 38.Op Fl N 39.Op Fl a maxcontig 40.Op Fl b Ar block-size 41.Op Fl c Ar cylinders 42.Op Fl d Ar rotdelay 43.Op Fl e Ar maxbpg 44.Op Fl f Ar frag-size 45.Op Fl i Ar bytes 46.Op Fl m Ar free space 47.Op Fl o Ar options 48.Op Fl s Ar size 49.Ar special node 50.Sh DESCRIPTION 51.Nm Newfs 52replaces the more obtuse 53.Xr mkfs 8 54program. 55Before running 56.Nm newfs 57or 58.Nm mount_mfs , 59the disk must be labeled using 60.Xr disklabel 8 . 61.Nm Newfs 62builds a file system on the specified special device 63basing its defaults on the information in the disk label. 64Typically the defaults are reasonable, however 65.Nm newfs 66has numerous options to allow the defaults to be selectively overridden. 67.Pp 68.Nm Mount_mfs 69is used to build a file system in virtual memory and then mount it 70on a specified node. 71.Nm Mount_mfs 72exits and the contents of the file system are lost 73when the file system is unmounted. 74If 75.Nm mount_mfs 76is sent a signal while running, 77for example during system shutdown, 78it will attempt to unmount its 79corresponding file system. 80The parameters to 81.Nm mount_mfs 82are the same as those to 83.Nm newfs . 84The special file is only used to read the disk label which provides 85a set of configuration parameters for the memory based file system. 86The special file is typically that of the primary swap area, 87since that is where the file system will be backed up when 88free memory gets low and the memory supporting 89the file system has to be paged. 90.Pp 91The following options define the general layout policies. 92.Bl -tag -width Fl 93.It Fl N 94Causes the file system parameters to be printed out 95without really creating the file system. 96.It Fl O 97Creates a 4.3BSD format filesystem. 98This options is primarily used to build root filesystems 99that can be understood by older boot ROMs. 100.It Fl a Ar maxcontig 101This specifies the maximum number of contiguous blocks that will be 102laid out before forcing a rotational delay (see the 103.Fl d 104option). 105The default value is one. 106See 107.Xr tunefs 8 108for more details on how to set this option. 109.It Fl b Ar block-size 110The block size of the file system, in bytes. 111.It Fl c Ar #cylinders/group 112The number of cylinders per cylinder group in a file system. 113The default value is 16. 114.It Fl d Ar rotdelay 115This specifies the expected time (in milliseconds) to service a transfer 116completion interrupt and initiate a new transfer on the same disk. 117The default is 4 milliseconds. 118See 119.Xr tunefs 8 120for more details on how to set this option. 121.ne 1i 122.It Fl e Ar maxbpg 123This indicates the maximum number of blocks any single file can 124allocate out of a cylinder group before it is forced to begin 125allocating blocks from another cylinder group. 126The default is about one quarter of the total blocks in a cylinder group. 127See 128.Xr tunefs 8 129for more details on how to set this option. 130.It Fl f Ar frag-size 131The fragment size of the file system in bytes. 132.It Fl i Ar number of bytes per inode 133This specifies the density of inodes in the file system. 134The default is to create an inode for each 2048 bytes of data space. 135If fewer inodes are desired, a larger number should be used; 136to create more inodes a smaller number should be given. 137.It Fl m Ar free space \&% 138The percentage of space reserved from normal users; the minimum free 139space threshold. 140The default value used is 10%. 141See 142.Xr tunefs 8 143for more details on how to set this option. 144.It Fl o Ar optimization\ preference 145.Pq ``space'' or ``time'' 146The file system can either be instructed to try to minimize the time spent 147allocating blocks, or to try to minimize the space fragmentation on the disk. 148If the value of minfree (see above) is less than 10%, 149the default is to optimize for space; 150if the value of minfree is greater than or equal to 10%, 151the default is to optimize for time. 152See 153.Xr tunefs 8 154for more details on how to set this option. 155.It Fl s Ar size 156The size of the file system in sectors. 157.El 158.Pp 159The following options override the standard sizes for the disk geometry. 160Their default values are taken from the disk label. 161Changing these defaults is useful only when using 162.Nm newfs 163to build a file system whose raw image will eventually be used on a 164different type of disk than the one on which it is initially created 165(for example on a write-once disk). 166Note that changing any of these values from their defaults will make 167it impossible for 168.Xr fsck 169to find the alternate superblocks if the standard superblock is lost. 170.Bl -tag -width Fl 171.It Fl S Ar sector-size 172The size of a sector in bytes (almost never anything but 512). 173.It Fl k Ar sector \&0 skew , per track 174Used to describe perturbations in the media format to compensate for 175a slow controller. 176Track skew is the offset of sector 0 on track N relative to sector 0 177on track N-1 on the same cylinder. 178.It Fl l Ar hardware sector interleave 179Used to describe perturbations in the media format to compensate for 180a slow controller. 181Interleave is physical sector interleave on each track, 182specified as the denominator of the ratio: 183.Dl sectors read/sectors passed over 184Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 185logical sector 0 is separated by one sector from logical sector 1. 186.It Fl p Ar spare sectors per track 187Spare sectors (bad sector replacements) are physical sectors that occupy 188space at the end of each track. 189They are not counted as part of the sectors/track 190.Pq Fl u 191since they are not available to the file system for data allocation. 192.It Fl r Ar revolutions/minute 193The speed of the disk in revolutions per minute. 194.ne 1i 195.It Fl t Ar #tracks/cylinder 196The number of tracks/cylinder available for data allocation by the file 197system. 198.It Fl u Ar sectors/track 199The number of sectors per track available for data allocation by the file 200system. 201This does not include sectors reserved at the end of each track for bad 202block replacement (see the 203.Fl p 204option.) 205.It Fl x Ar spare sectors per cylinder 206Spare sectors (bad sector replacements) are physical sectors that occupy 207space at the end of the last track in the cylinder. 208They are deducted from the sectors/track 209.Pq Fl u 210of the last track of each cylinder since they are not available to the file 211system for data allocation. 212.El 213.Pp 214The options to the 215.Nm mount_mfs 216command are as described for the 217.Nm newfs 218command, except for the 219.Fl o 220option. 221.Pp 222That option is as follows: 223.Bl -tag -width indent 224.It Fl o 225Options are specified with a 226.Fl o 227flag followed by a comma separated string of options. 228See the 229.Xr mount 8 230man page for possible options and their meanings. 231.El 232.Sh SEE ALSO 233.Xr disktab 5 , 234.Xr fs 5 , 235.Xr dumpfs 8 , 236.Xr disklabel 8 , 237.Xr diskpart 8 , 238.Xr fsck 8 , 239.Xr format 8 , 240.Xr mount 8 , 241.Xr tunefs 8 242.Rs 243.%A M. McKusick 244.%A W. Joy 245.%A S. Leffler 246.%A R. Fabry 247.%T A Fast File System for UNIX , 248.%J ACM Transactions on Computer Systems 2 249.%V 3 250.%P pp 181-197 251.%D August 1984 252.%O (reprinted in the BSD System Manager's Manual) 253.Re 254.Sh HISTORY 255The 256.Nm 257command appeared in 258.Bx 4.2 . 259