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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: src/sbin/newfs/newfs.8,v 1.26.2.15 2003/05/13 12:16:08 joerg Exp $ 34.\" $DragonFly: src/sbin/newfs/newfs.8,v 1.4 2004/05/19 22:52:34 dillon Exp $ 35.\" 36.Dd May 13, 2003 37.Dt NEWFS 8 38.Os 39.Sh NAME 40.Nm newfs , 41.Nm mount_mfs 42.Nd construct a new file system 43.Sh SYNOPSIS 44.Nm 45.Op Fl NCOU 46.Op Fl S Ar sector-size 47.Op Fl T Ar disktype 48.Op Fl a Ar maxcontig 49.Op Fl b Ar block-size 50.Op Fl c Ar cylinders 51.Op Fl d Ar rotdelay 52.Op Fl e Ar maxbpg 53.Op Fl f Ar frag-size 54.Op Fl g Ar avgfilesize 55.Op Fl h Ar avfpdir 56.Op Fl i Ar bytes 57.Op Fl k Ar skew 58.Op Fl l Ar interleave 59.Op Fl m Ar free space 60.Op Fl n Ar rotational positions 61.Op Fl o Ar optimization 62.Op Fl p Ar sectors 63.Op Fl r Ar revolutions 64.Op Fl s Ar size 65.Op Fl t Ar tracks 66.Op Fl u Ar sectors 67.Op Fl v 68.Op Fl x Ar sectors 69.Ar special 70.Nm mount_mfs 71.Op Fl NU 72.Op Fl F Ar file 73.Op Fl T Ar disktype 74.Op Fl a Ar maxcontig 75.Op Fl b Ar block-size 76.Op Fl c Ar cylinders 77.Op Fl d Ar rotdelay 78.Op Fl e Ar maxbpg 79.Op Fl f Ar frag-size 80.Op Fl i Ar bytes 81.Op Fl m Ar free space 82.Op Fl n Ar rotational positions 83.Op Fl o Ar options 84.Op Fl s Ar size 85.Op Fl v 86.Ar special node 87.Sh DESCRIPTION 88.Nm Newfs 89is used to initialize and clear filesystems before first use. 90Before running 91.Nm 92or 93.Nm mount_mfs , 94the disk must be labeled using 95.Xr disklabel 8 . 96.Nm Newfs 97builds a file system on the specified special file. 98(We often refer to the 99.Dq special file 100as the 101.Dq disk , 102although the special file need not be a physical disk. 103In fact, it need not even be special.) 104Typically the defaults are reasonable, however 105.Nm 106has numerous options to allow the defaults to be selectively overridden. 107.Pp 108.Nm Mount_mfs 109is used to build a file system in virtual memory and then mount it 110on a specified node. 111.Nm Mount_mfs 112exits and the contents of the file system are lost 113when the file system is unmounted. 114If 115.Nm mount_mfs 116is sent a signal while running, 117for example during system shutdown, 118it will attempt to unmount its 119corresponding file system. 120The parameters to 121.Nm mount_mfs 122are the same as those to 123.Nm . 124If the 125.Fl T 126flag is specified (see below), the special file is unused. 127Otherwise, it is only used to read the disk label which provides 128a set of configuration parameters for the memory based file system. 129The special file is typically that of the primary swap area, 130since that is where the file system will be backed up when 131free memory gets low and the memory supporting 132the file system has to be paged. 133.Pp 134.Nm mount_mfs 135creates the raw character device 136.Pa /dev/mfs<PID> 137to represent the backing store while the mount is active. This device may 138be read but not written and allows swap-based MFS filesystems to be dumped 139if desired. 140.Pp 141The following options define the general layout policies: 142.Bl -tag -width indent 143.It Fl T Ar disktype 144For backward compatibility and for 145.Nm mount_mfs . 146.It Fl F Ar file 147.Nm Mount_mfs 148will use this file for the image of the filesystem. When 149.Nm mount_mfs 150exits, this file will be left behind. 151.It Fl C 152Tell 153.Nm Mount_mfs 154to copy the underlying filesystem into the MFS mount being created 155over it. 156.It Fl N 157Cause the file system parameters to be printed out 158without really creating the file system. 159.It Fl O 160Create a 161.Bx 4.3 162format filesystem. 163This options is primarily used to build root filesystems 164that can be understood by older boot ROMs. 165.It Fl T 166Use information for the specified disk from 167.Pa /etc/disktab 168instead of trying to get the information from a disklabel. 169.It Fl U 170Enables soft updates on the new filesystem. 171.It Fl a Ar maxcontig 172Specify the maximum number of contiguous blocks that will be 173laid out before forcing a rotational delay (see the 174.Fl d 175option). 176The default value is 1. 177See 178.Xr tunefs 8 179for more details on how to set this option. 180.It Fl b Ar block-size 181The block size of the file system, in bytes. It must be a power of 2. The 182default size is 16384 bytes, and the smallest allowable size is 4096 bytes. 183The optimal block:fragment ratio is 8:1. 184Other ratios are possible, but are not recommended, 185and may produce unpredictable results. 186.It Fl c Ar #cylinders/group 187The number of cylinders per cylinder group in a file system. The default 188is to compute the maximum allowed by the other parameters. This value is 189dependent on a number of other parameters, in particular the block size 190and the number of bytes per inode. 191.It Fl d Ar rotdelay 192This parameter once specified the minimum time in milliseconds required to 193initiate another disk transfer on the same cylinder. It was used in determining 194the rotationally optimal layout for disk blocks within a file. Modern disks 195with read/write-behind achieve higher performance with this feature disabled, so 196this value should be left at the default value of 0 milliseconds. See 197.Xr tunefs 8 198for more details on how to set this option. 199.It Fl e Ar maxbpg 200Indicate the maximum number of blocks any single file can 201allocate out of a cylinder group before it is forced to begin 202allocating blocks from another cylinder group. 203The default is about one quarter of the total blocks in a cylinder group. 204See 205.Xr tunefs 8 206for more details on how to set this option. 207.It Fl f Ar frag-size 208The fragment size of the file system in bytes. It must be a power of two 209ranging in value between 210.Ar blocksize Ns /8 211and 212.Ar blocksize . 213The default is 2048 bytes. 214.It Fl g Ar avgfilesize 215The expected average file size for the file system. 216.It Fl h Ar avgfpdir 217The expected average number of files per directory on the file system. 218.It Fl i Ar number of bytes per inode 219Specify the density of inodes in the file system. 220The default is to create an inode for every 221.Pq 4 * Ar frag-size 222bytes of data space. 223If fewer inodes are desired, a larger number should be used; 224to create more inodes a smaller number should be given. 225One inode is required for each distinct file, so this value effectively 226specifies the average file size on the file system. 227.It Fl m Ar free space \&% 228The percentage of space reserved from normal users; the minimum free 229space threshold. 230The default value used is 231defined by 232.Dv MINFREE 233from 234.Aq Pa ufs/ffs/fs.h , 235currently 8%. 236See 237.Xr tunefs 8 238for more details on how to set this option. 239.It Fl n Ar number of distinguished rotational positions 240UFS has the ability to keep track of the availability of blocks at different 241rotational positions, so that it could lay out the data to be picked up with 242minimum rotational latency. This parameter specifies the default number of 243rotational positions to distinguish. 244.Pp 245Nowadays this value should be set to 1 (which essentially disables the 246rotational position table) because modern drives with read-ahead and 247write-behind do better without the rotational position table. 248.It Fl o Ar optimization\ preference 249.Pq Ar space No or Ar time . 250The file system can either be instructed to try to minimize the time spent 251allocating blocks, or to try to minimize the space fragmentation on the disk. 252If the value of minfree (see above) is less than 8%, 253the default is to optimize for 254.Ar space ; 255if the value of minfree is greater than or equal to 8%, 256the default is to optimize for 257.Ar time . 258See 259.Xr tunefs 8 260for more details on how to set this option. 261.It Fl s Ar size 262The size of the file system in sectors. This value defaults to the size of the 263raw partition specified in 264.Ar special 265(in other words, 266.Nm 267will use the entire partition for the file system). 268.It Fl v 269Specify that the disk does not contain any partitions, and that 270.Nm 271should build a file system on the whole disk. 272This option is useful for synthetic disks such as 273.Nm vinum . 274.El 275.Pp 276The following options override the standard sizes for the disk geometry. 277Their default values are taken from the disk label. 278Changing these defaults is useful only when using 279.Nm 280to build a file system whose raw image will eventually be used on a 281different type of disk than the one on which it is initially created 282(for example on a write-once disk). 283Note that changing any of these values from their defaults will make 284it impossible for 285.Xr fsck 8 286to find the alternate superblocks if the standard superblock is lost. 287.Bl -tag -width indent 288.It Fl S Ar sector-size 289The size of a sector in bytes (almost never anything but 512). 290.It Fl k Ar sector \&0 skew , per track 291Used to describe perturbations in the media format to compensate for 292a slow controller. 293Track skew is the offset of sector 0 on track N relative to sector 0 294on track N-1 on the same cylinder. 295This option is of historical importance only; modern controllers are always fast 296enough to handle operations back-to-back. 297.It Fl l Ar hardware sector interleave 298Used to describe perturbations in the media format to compensate for 299a slow controller. 300Interleave is physical sector interleave on each track, 301specified as the denominator of the ratio: 302.Dl sectors read/sectors passed over 303Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 304logical sector 0 is separated by one sector from logical sector 1. 305This option is of historical importance only; the physical sector layout of 306modern disks is not visible from outside. 307.It Fl p Ar spare sectors per track 308Spare sectors (bad sector replacements) are physical sectors that occupy 309space at the end of each track. 310They are not counted as part of the sectors/track 311.Pq Fl u 312since they are not available to the file system for data allocation. 313This option is of historical importance only. Modern disks perform their own 314bad sector allocation. 315.It Fl r Ar revolutions/minute 316The speed of the disk in revolutions per minute. This value is no longer of 317interest, since all the parameters which depend on it are usually disabled. 318.It Fl t Ar #tracks/cylinder 319The number of tracks/cylinder available for data allocation by the file 320system. 321The default is 1. 322If zero is specified, the value from the disklabel will be used. 323.It Fl u Ar sectors/track 324The number of sectors per track available for data allocation by the file 325system. 326The default is 4096. 327If zero is specified, the value from the disklabel will be used. 328This does not include sectors reserved at the end of each track for bad 329block replacement (see the 330.Fl p 331option). 332.It Fl x Ar spare sectors per cylinder 333Spare sectors (bad sector replacements) are physical sectors that occupy 334space at the end of the last track in the cylinder. 335They are deducted from the sectors/track 336.Pq Fl u 337of the last track of each cylinder since they are not available to the file 338system for data allocation. 339This option is of historical importance only. Modern disks perform their own 340bad sector allocation. 341.El 342.Pp 343The options to the 344.Nm mount_mfs 345command are as described for the 346.Nm 347command, except for the 348.Fl o 349option. 350.Pp 351That option is as follows: 352.Bl -tag -width indent 353.It Fl o 354Options are specified with a 355.Fl o 356flag followed by a comma separated string of options. 357See the 358.Xr mount 8 359man page for possible options and their meanings. 360.El 361.Sh EXAMPLES 362.Dl newfs /dev/ad3s1a 363.Pp 364Creates a new ufs file system on 365.Pa ad3s1a . 366.Nm 367will use a block size of 16384 bytes, a fragment size of 2048 bytes 368and the largest possible number of cylinders per group. 369These values tend to produce better performance for most applications 370than the historical defaults 371(8192 byte block size and 1024 byte fragment size). 372This large fragment size 373may lead to large amounts of wasted space 374on filesystems that contain a large number of small files. 375.Pp 376.Dl mount_mfs -s 131072 -o nosuid,nodev,nosymfollow /dev/da0s1b /tmp 377.Pp 378Mount a 64 MB large memory file system on 379.Pa /tmp , 380with 381.Xr mount 8 382options 383.Ar nosuid , 384.Ar nodev , 385and 386.Ar nosymfollow . 387.Sh SEE ALSO 388.Xr fdformat 1 , 389.Xr disktab 5 , 390.Xr fs 5 , 391.Xr camcontrol 8 , 392.Xr disklabel 8 , 393.Xr diskpart 8 , 394.Xr dumpfs 8 , 395.Xr fsck 8 , 396.Xr mount 8 , 397.Xr tunefs 8 , 398.Xr vinum 8 399.Rs 400.%A M. McKusick 401.%A W. Joy 402.%A S. Leffler 403.%A R. Fabry 404.%T A Fast File System for UNIX 405.%J ACM Transactions on Computer Systems 2 406.%V 3 407.%P pp 181-197 408.%D August 1984 409.%O (reprinted in the BSD System Manager's Manual) 410.Re 411.Sh HISTORY 412The 413.Nm 414command appeared in 415.Bx 4.2 . 416