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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.\" 35.Dd October 7, 2011 36.Dt NEWFS 8 37.Os 38.Sh NAME 39.Nm newfs , 40.Nm mount_mfs 41.Nd construct a new UFS file system 42.Sh SYNOPSIS 43.Nm 44.Op Fl L Ar volname 45.Op Fl NCEOU 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 E 147Use TRIM to erase the device's data before creating the file system. 148The underlying device must have the TRIM sysctl enabled. 149Only devices that support TRIM will have such a sysctl option 150.Va ( kern.cam.da.X.trim_enabled ) . 151.It Fl F Ar file 152.Nm Mount_mfs 153will use this file for the image of the filesystem. When 154.Nm mount_mfs 155exits, this file will be left behind. 156.It Fl C 157Tell 158.Nm Mount_mfs 159to copy the underlying filesystem into the MFS mount being created 160over it. 161.It Fl L Ar volname 162Add a volume label to the new file system. 163.It Fl N 164Cause the file system parameters to be printed out 165without really creating the file system. 166.It Fl O 167Create a 168.Bx 4.3 169format filesystem. 170This options is primarily used to build root filesystems 171that can be understood by older boot ROMs. 172.It Fl T 173Use information for the specified disk from 174.Pa /etc/disktab 175instead of trying to get geometry information from the 176storage device. 177.It Fl U 178Enables soft updates on the new filesystem. 179.It Fl a Ar maxcontig 180Specify the maximum number of contiguous blocks that will be 181laid out before forcing a rotational delay (see the 182.Fl d 183option). 184The default value is 1. 185See 186.Xr tunefs 8 187for more details on how to set this option. 188.It Fl b Ar block-size 189The block size of the file system, in bytes. It must be a power of 2. The 190default size is 16384 bytes, and the smallest allowable size is 4096 bytes. 191The optimal block:fragment ratio is 8:1. 192Other ratios are possible, but are not recommended, 193and may produce unpredictable results. 194.It Fl c Ar #cylinders/group 195The number of cylinders per cylinder group in a file system. The default 196is to compute the maximum allowed by the other parameters. This value is 197dependent on a number of other parameters, in particular the block size 198and the number of bytes per inode. 199.It Fl d Ar rotdelay 200This parameter once specified the minimum time in milliseconds required to 201initiate another disk transfer on the same cylinder. It was used in determining 202the rotationally optimal layout for disk blocks within a file. Modern disks 203with read/write-behind achieve higher performance with this feature disabled, so 204this value should be left at the default value of 0 milliseconds. See 205.Xr tunefs 8 206for more details on how to set this option. 207.It Fl e Ar maxbpg 208Indicate the maximum number of blocks any single file can 209allocate out of a cylinder group before it is forced to begin 210allocating blocks from another cylinder group. 211The default is about one quarter of the total blocks in a cylinder group. 212See 213.Xr tunefs 8 214for more details on how to set this option. 215.It Fl f Ar frag-size 216The fragment size of the file system in bytes. It must be a power of two 217ranging in value between 218.Ar blocksize Ns /8 219and 220.Ar blocksize . 221The default is 2048 bytes. 222.It Fl g Ar avgfilesize 223The expected average file size for the file system. 224.It Fl h Ar avgfpdir 225The expected average number of files per directory on the file system. 226.It Fl i Ar number of bytes per inode 227Specify the density of inodes in the file system. 228The default is to create an inode for every 229.Pq 4 * Ar frag-size 230bytes of data space. 231If fewer inodes are desired, a larger number should be used; 232to create more inodes a smaller number should be given. 233One inode is required for each distinct file, so this value effectively 234specifies the average file size on the file system. 235.It Fl m Ar free space \&% 236The percentage of space reserved from normal users; the minimum free 237space threshold. 238The default value used is 239defined by 240.Dv MINFREE 241from 242.In ufs/ffs/fs.h , 243currently 8%. 244See 245.Xr tunefs 8 246for more details on how to set this option. 247.It Fl n Ar number of distinguished rotational positions 248.Xr UFS 5 249has the ability to keep track of the availability of blocks at different 250rotational positions, so that it could lay out the data to be picked up with 251minimum rotational latency. This parameter specifies the default number of 252rotational positions to distinguish. 253.Pp 254Nowadays this value should be set to 1 (which essentially disables the 255rotational position table) because modern drives with read-ahead and 256write-behind do better without the rotational position table. 257.It Fl o Ar optimization\ preference 258.Pq Cm space No or Cm time . 259The file system can either be instructed to try to minimize the time spent 260allocating blocks, or to try to minimize the space fragmentation on the disk. 261If the value of minfree (see above) is less than 8%, 262the default is to optimize for 263.Cm space ; 264if the value of minfree is greater than or equal to 8%, 265the default is to optimize for 266.Cm time . 267See 268.Xr tunefs 8 269for more details on how to set this option. 270.It Fl s Ar size 271The size of the file system in sectors. This value defaults to the size of the 272raw partition specified in 273.Ar special 274(in other words, 275.Nm 276will use the entire partition for the file system). 277.It Fl v 278Specify that the disk does not contain any partitions, and that 279.Nm 280should build a file system on the whole disk. 281This option is useful for synthetic disks such as 282.Nm vinum . 283It may also be used to allow 284.Nm 285to operate on regular files. 286When operating on a regular file, 287.Nm 288will synthesize a reasonable geometry for the filesystem. 289.El 290.Pp 291The following options override the standard sizes for the disk geometry. 292Their default values are taken from the disk label. 293Changing these defaults is useful only when using 294.Nm 295to build a file system whose raw image will eventually be used on a 296different type of disk than the one on which it is initially created 297(for example on a write-once disk). 298Note that changing any of these values from their defaults will make 299it impossible for 300.Xr fsck 8 301to find the alternate superblocks if the standard superblock is lost. 302.Bl -tag -width indent 303.It Fl S Ar sector-size 304The size of a sector in bytes (almost never anything but 512). 305.It Fl k Ar sector \&0 skew , per track 306Used to describe perturbations in the media format to compensate for 307a slow controller. 308Track skew is the offset of sector 0 on track N relative to sector 0 309on track N-1 on the same cylinder. 310This option is of historical importance only; modern controllers are always fast 311enough to handle operations back-to-back. 312.It Fl l Ar hardware sector interleave 313Used to describe perturbations in the media format to compensate for 314a slow controller. 315Interleave is physical sector interleave on each track, 316specified as the denominator of the ratio: 317.Dl sectors read/sectors passed over 318Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 319logical sector 0 is separated by one sector from logical sector 1. 320This option is of historical importance only; the physical sector layout of 321modern disks is not visible from outside. 322.It Fl p Ar spare sectors per track 323Spare sectors (bad sector replacements) are physical sectors that occupy 324space at the end of each track. 325They are not counted as part of the sectors/track 326.Pq Fl u 327since they are not available to the file system for data allocation. 328This option is of historical importance only. Modern disks perform their own 329bad sector allocation. 330.It Fl r Ar revolutions/minute 331The speed of the disk in revolutions per minute. This value is no longer of 332interest, since all the parameters which depend on it are usually disabled. 333.It Fl t Ar #tracks/cylinder 334The number of tracks/cylinder available for data allocation by the file 335system. 336The default is 1. 337If zero is specified, the value from the device geometry will be used. 338.It Fl u Ar sectors/track 339The number of sectors per track available for data allocation by the file 340system. 341The default is 4096. 342If zero is specified, the value from the device geometry will be used. 343This does not include sectors reserved at the end of each track for bad 344block replacement (see the 345.Fl p 346option). 347.It Fl x Ar spare sectors per cylinder 348Spare sectors (bad sector replacements) are physical sectors that occupy 349space at the end of the last track in the cylinder. 350They are deducted from the sectors/track 351.Pq Fl u 352of the last track of each cylinder since they are not available to the file 353system for data allocation. 354This option is of historical importance only. Modern disks perform their own 355bad sector allocation. 356.El 357.Pp 358The options to the 359.Nm mount_mfs 360command are as described for the 361.Nm 362command, except for the 363.Fl o 364option. 365.Pp 366That option is as follows: 367.Bl -tag -width indent 368.It Fl o 369Options are specified with a 370.Fl o 371flag followed by a comma separated string of options. 372See the 373.Xr mount 8 374man page for possible options and their meanings. 375.El 376.Sh EXAMPLES 377.Dl newfs /dev/ad3s1a 378.Pp 379Creates a new 380.Xr UFS 5 381file system on 382.Pa ad3s1a . 383.Nm 384will use a block size of 16384 bytes, a fragment size of 2048 bytes 385and the largest possible number of cylinders per group. 386These values tend to produce better performance for most applications 387than the historical defaults 388(8192 byte block size and 1024 byte fragment size). 389This large fragment size 390may lead to large amounts of wasted space 391on filesystems that contain a large number of small files. 392.Pp 393.Dl mount_mfs -s 131072 -o nosuid,nodev,nosymfollow /dev/da0s1b /tmp 394.Pp 395Mount a 64 MB large memory file system on 396.Pa /tmp , 397with 398.Xr mount 8 399options 400.Cm nosuid , 401.Cm nodev , 402and 403.Cm nosymfollow . 404.Sh SEE ALSO 405.Xr fdformat 1 , 406.Xr disktab 5 , 407.Xr fs 5 , 408.Xr UFS 5 , 409.Xr camcontrol 8 , 410.Xr disklabel 8 , 411.Xr dumpfs 8 , 412.Xr fsck 8 , 413.Xr mount 8 , 414.Xr tunefs 8 , 415.Xr vinum 8 416.Rs 417.%A M. McKusick 418.%A W. Joy 419.%A S. Leffler 420.%A R. Fabry 421.%T A Fast File System for UNIX 422.%J ACM Transactions on Computer Systems 2 423.%V 3 424.%P pp 181-197 425.%D August 1984 426.%O (reprinted in the BSD System Manager's Manual) 427.Re 428.Sh HISTORY 429The 430.Nm 431command appeared in 432.Bx 4.2 . 433