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 8.6 (Berkeley) 05/03/95 7.\" 8.Dd 9.Dt NEWFS 8 10.Os BSD 4.2 11.Sh NAME 12.Nm newfs , 13.Nm mount_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 T Ar disktype 20.Op Fl a Ar maxcontig 21.Op Fl b Ar block-size 22.Op Fl c Ar cylinders 23.Op Fl d Ar rotdelay 24.Op Fl e Ar maxbpg 25.Op Fl f Ar frag-size 26.Op Fl i Ar bytes 27.Op Fl k Ar skew 28.Op Fl l Ar interleave 29.Op Fl m Ar free space 30.Op Fl n Ar rotational positions 31.Op Fl o Ar optimization 32.Op Fl p Ar sectors 33.Op Fl r Ar revolutions 34.Op Fl s Ar size 35.Op Fl t Ar tracks 36.Op Fl u Ar sectors 37.Op Fl x Ar sectors 38.Ar special 39.Nm mount_mfs 40.Op Fl N 41.Op Fl T Ar disktype 42.Op Fl a Ar maxcontig 43.Op Fl b Ar block-size 44.Op Fl c Ar cylinders 45.Op Fl d Ar rotdelay 46.Op Fl e Ar maxbpg 47.Op Fl f Ar frag-size 48.Op Fl i Ar bytes 49.Op Fl m Ar free space 50.Op Fl n Ar rotational positions 51.Op Fl o Ar options 52.Op Fl s Ar size 53.Ar special node 54.Sh DESCRIPTION 55.Nm Newfs 56replaces the more obtuse 57.Xr mkfs 8 58program. 59Before running 60.Nm newfs 61or 62.Nm mount_mfs , 63the disk must be labeled using 64.Xr disklabel 8 . 65.Nm Newfs 66builds a file system on the specified special device 67basing its defaults on the information in the disk label. 68Typically the defaults are reasonable, however 69.Nm newfs 70has numerous options to allow the defaults to be selectively overridden. 71.Pp 72.Nm Mount_mfs 73is used to build a file system in virtual memory and then mount it 74on a specified node. 75.Nm Mount_mfs 76exits and the contents of the file system are lost 77when the file system is unmounted. 78If 79.Nm mount_mfs 80is sent a signal while running, 81for example during system shutdown, 82it will attempt to unmount its 83corresponding file system. 84The parameters to 85.Nm mount_mfs 86are the same as those to 87.Nm newfs . 88If the 89.Fl T 90flag is specified (see below), the special file is unused. 91Otherwise, it is only used to read the disk label which provides 92a set of configuration parameters for the memory based file system. 93The special file is typically that of the primary swap area, 94since that is where the file system will be backed up when 95free memory gets low and the memory supporting 96the file system has to be paged. 97.Pp 98The following options define the general layout policies. 99.Bl -tag -width Fl 100.It Fl N 101Causes the file system parameters to be printed out 102without really creating the file system. 103.It Fl O 104Creates a 4.3BSD format filesystem. 105This options is primarily used to build root filesystems 106that can be understood by older boot ROMs. 107.It Fl T 108Uses information for the specified disk from 109.Pa /etc/disktab 110instead of trying to get the information from a disklabel. 111.It Fl a Ar maxcontig 112This specifies the maximum number of contiguous blocks that will be 113laid out before forcing a rotational delay (see the 114.Fl d 115option). 116The default value is one. 117See 118.Xr tunefs 8 119for more details on how to set this option. 120.It Fl b Ar block-size 121The block size of the file system, in bytes. 122.It Fl c Ar #cylinders/group 123The number of cylinders per cylinder group in a file system. 124The default value is 16. 125.It Fl d Ar rotdelay 126This specifies the expected time (in milliseconds) to service a transfer 127completion interrupt and initiate a new transfer on the same disk. 128The default is 4 milliseconds. 129See 130.Xr tunefs 8 131for more details on how to set this option. 132.ne 1i 133.It Fl e Ar maxbpg 134This indicates the maximum number of blocks any single file can 135allocate out of a cylinder group before it is forced to begin 136allocating blocks from another cylinder group. 137The default is about one quarter of the total blocks in a cylinder group. 138See 139.Xr tunefs 8 140for more details on how to set this option. 141.It Fl f Ar frag-size 142The fragment size of the file system in bytes. 143.It Fl i Ar number of bytes per inode 144This specifies the density of inodes in the file system. 145The default is to create an inode for each 2048 bytes of data space. 146If fewer inodes are desired, a larger number should be used; 147to create more inodes a smaller number should be given. 148.It Fl m Ar free space \&% 149The percentage of space reserved from normal users; the minimum free 150space threshold. 151The default value used is 10%. 152See 153.Xr tunefs 8 154for more details on how to set this option. 155.It Fl n Ar rotational\ positions 156Determines how many rotational time slots there are in 157one revolution of the disk. 158.It Fl o Ar optimization\ preference 159.Pq ``space'' or ``time'' 160The file system can either be instructed to try to minimize the time spent 161allocating blocks, or to try to minimize the space fragmentation on the disk. 162If the value of minfree (see above) is less than 10%, 163the default is to optimize for space; 164if the value of minfree is greater than or equal to 10%, 165the default is to optimize for time. 166See 167.Xr tunefs 8 168for more details on how to set this option. 169.It Fl s Ar size 170The size of the file system in sectors. 171.El 172.Pp 173The following options override the standard sizes for the disk geometry. 174Their default values are taken from the disk label. 175Changing these defaults is useful only when using 176.Nm newfs 177to build a file system whose raw image will eventually be used on a 178different type of disk than the one on which it is initially created 179(for example on a write-once disk). 180Note that changing any of these values from their defaults will make 181it impossible for 182.Xr fsck 183to find the alternate superblocks if the standard superblock is lost. 184.Bl -tag -width Fl 185.It Fl S Ar sector-size 186The size of a sector in bytes (almost never anything but 512). 187.It Fl k Ar sector \&0 skew , per track 188Used to describe perturbations in the media format to compensate for 189a slow controller. 190Track skew is the offset of sector 0 on track N relative to sector 0 191on track N-1 on the same cylinder. 192.It Fl l Ar hardware sector interleave 193Used to describe perturbations in the media format to compensate for 194a slow controller. 195Interleave is physical sector interleave on each track, 196specified as the denominator of the ratio: 197.Dl sectors read/sectors passed over 198Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 199logical sector 0 is separated by one sector from logical sector 1. 200.It Fl p Ar spare sectors per track 201Spare sectors (bad sector replacements) are physical sectors that occupy 202space at the end of each track. 203They are not counted as part of the sectors/track 204.Pq Fl u 205since they are not available to the file system for data allocation. 206.It Fl r Ar revolutions/minute 207The speed of the disk in revolutions per minute. 208.ne 1i 209.It Fl t Ar #tracks/cylinder 210The number of tracks/cylinder available for data allocation by the file 211system. 212.It Fl u Ar sectors/track 213The number of sectors per track available for data allocation by the file 214system. 215This does not include sectors reserved at the end of each track for bad 216block replacement (see the 217.Fl p 218option.) 219.It Fl x Ar spare sectors per cylinder 220Spare sectors (bad sector replacements) are physical sectors that occupy 221space at the end of the last track in the cylinder. 222They are deducted from the sectors/track 223.Pq Fl u 224of the last track of each cylinder since they are not available to the file 225system for data allocation. 226.El 227.Pp 228The options to the 229.Nm mount_mfs 230command are as described for the 231.Nm newfs 232command, except for the 233.Fl o 234option. 235.Pp 236That option is as follows: 237.Bl -tag -width indent 238.It Fl o 239Options are specified with a 240.Fl o 241flag followed by a comma separated string of options. 242See the 243.Xr mount 8 244man page for possible options and their meanings. 245.El 246.Sh SEE ALSO 247.Xr disktab 5 , 248.Xr fs 5 , 249.Xr dumpfs 8 , 250.Xr disklabel 8 , 251.Xr diskpart 8 , 252.Xr fsck 8 , 253.Xr format 8 , 254.Xr mount 8 , 255.Xr tunefs 8 256.Rs 257.%A M. McKusick 258.%A W. Joy 259.%A S. Leffler 260.%A R. Fabry 261.%T A Fast File System for UNIX , 262.%J ACM Transactions on Computer Systems 2 263.%V 3 264.%P pp 181-197 265.%D August 1984 266.%O (reprinted in the BSD System Manager's Manual) 267.Re 268.Sh HISTORY 269The 270.Nm 271command appeared in 272.Bx 4.2 . 273