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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 1.3 2003/12/01 04:36:57 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 134The following options define the general layout policies: 135.Bl -tag -width indent 136.It Fl T Ar disktype 137For backward compatibility and for 138.Nm mount_mfs . 139.It Fl F Ar file 140.Nm Mount_mfs 141will use this file for the image of the filesystem. When 142.Nm mount_mfs 143exits, this file will be left behind. 144.It Fl C 145Tell 146.Nm Mount_mfs 147to copy the underlying filesystem into the MFS mount being created 148over it. 149.It Fl N 150Cause the file system parameters to be printed out 151without really creating the file system. 152.It Fl O 153Create a 154.Bx 4.3 155format filesystem. 156This options is primarily used to build root filesystems 157that can be understood by older boot ROMs. 158.It Fl T 159Use information for the specified disk from 160.Pa /etc/disktab 161instead of trying to get the information from a disklabel. 162.It Fl U 163Enables soft updates on the new filesystem. 164.It Fl a Ar maxcontig 165Specify the maximum number of contiguous blocks that will be 166laid out before forcing a rotational delay (see the 167.Fl d 168option). 169The default value is 1. 170See 171.Xr tunefs 8 172for more details on how to set this option. 173.It Fl b Ar block-size 174The block size of the file system, in bytes. It must be a power of 2. The 175default size is 16384 bytes, and the smallest allowable size is 4096 bytes. 176The optimal block:fragment ratio is 8:1. 177Other ratios are possible, but are not recommended, 178and may produce unpredictable results. 179.It Fl c Ar #cylinders/group 180The number of cylinders per cylinder group in a file system. The default 181is to compute the maximum allowed by the other parameters. This value is 182dependent on a number of other parameters, in particular the block size 183and the number of bytes per inode. 184.It Fl d Ar rotdelay 185This parameter once specified the minimum time in milliseconds required to 186initiate another disk transfer on the same cylinder. It was used in determining 187the rotationally optimal layout for disk blocks within a file. Modern disks 188with read/write-behind achieve higher performance with this feature disabled, so 189this value should be left at the default value of 0 milliseconds. See 190.Xr tunefs 8 191for more details on how to set this option. 192.It Fl e Ar maxbpg 193Indicate the maximum number of blocks any single file can 194allocate out of a cylinder group before it is forced to begin 195allocating blocks from another cylinder group. 196The default is about one quarter of the total blocks in a cylinder group. 197See 198.Xr tunefs 8 199for more details on how to set this option. 200.It Fl f Ar frag-size 201The fragment size of the file system in bytes. It must be a power of two 202ranging in value between 203.Ar blocksize Ns /8 204and 205.Ar blocksize . 206The default is 2048 bytes. 207.It Fl g Ar avgfilesize 208The expected average file size for the file system. 209.It Fl h Ar avgfpdir 210The expected average number of files per directory on the file system. 211.It Fl i Ar number of bytes per inode 212Specify the density of inodes in the file system. 213The default is to create an inode for every 214.Pq 4 * Ar frag-size 215bytes of data space. 216If fewer inodes are desired, a larger number should be used; 217to create more inodes a smaller number should be given. 218One inode is required for each distinct file, so this value effectively 219specifies the average file size on the file system. 220.It Fl m Ar free space \&% 221The percentage of space reserved from normal users; the minimum free 222space threshold. 223The default value used is 224defined by 225.Dv MINFREE 226from 227.Aq Pa ufs/ffs/fs.h , 228currently 8%. 229See 230.Xr tunefs 8 231for more details on how to set this option. 232.It Fl n Ar number of distinguished rotational positions 233UFS has the ability to keep track of the availability of blocks at different 234rotational positions, so that it could lay out the data to be picked up with 235minimum rotational latency. This parameter specifies the default number of 236rotational positions to distinguish. 237.Pp 238Nowadays this value should be set to 1 (which essentially disables the 239rotational position table) because modern drives with read-ahead and 240write-behind do better without the rotational position table. 241.It Fl o Ar optimization\ preference 242.Pq Ar space No or Ar time . 243The file system can either be instructed to try to minimize the time spent 244allocating blocks, or to try to minimize the space fragmentation on the disk. 245If the value of minfree (see above) is less than 8%, 246the default is to optimize for 247.Ar space ; 248if the value of minfree is greater than or equal to 8%, 249the default is to optimize for 250.Ar time . 251See 252.Xr tunefs 8 253for more details on how to set this option. 254.It Fl s Ar size 255The size of the file system in sectors. This value defaults to the size of the 256raw partition specified in 257.Ar special 258(in other words, 259.Nm 260will use the entire partition for the file system). 261.It Fl v 262Specify that the disk does not contain any partitions, and that 263.Nm 264should build a file system on the whole disk. 265This option is useful for synthetic disks such as 266.Nm vinum . 267.El 268.Pp 269The following options override the standard sizes for the disk geometry. 270Their default values are taken from the disk label. 271Changing these defaults is useful only when using 272.Nm 273to build a file system whose raw image will eventually be used on a 274different type of disk than the one on which it is initially created 275(for example on a write-once disk). 276Note that changing any of these values from their defaults will make 277it impossible for 278.Xr fsck 8 279to find the alternate superblocks if the standard superblock is lost. 280.Bl -tag -width indent 281.It Fl S Ar sector-size 282The size of a sector in bytes (almost never anything but 512). 283.It Fl k Ar sector \&0 skew , per track 284Used to describe perturbations in the media format to compensate for 285a slow controller. 286Track skew is the offset of sector 0 on track N relative to sector 0 287on track N-1 on the same cylinder. 288This option is of historical importance only; modern controllers are always fast 289enough to handle operations back-to-back. 290.It Fl l Ar hardware sector interleave 291Used to describe perturbations in the media format to compensate for 292a slow controller. 293Interleave is physical sector interleave on each track, 294specified as the denominator of the ratio: 295.Dl sectors read/sectors passed over 296Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies 297logical sector 0 is separated by one sector from logical sector 1. 298This option is of historical importance only; the physical sector layout of 299modern disks is not visible from outside. 300.It Fl p Ar spare sectors per track 301Spare sectors (bad sector replacements) are physical sectors that occupy 302space at the end of each track. 303They are not counted as part of the sectors/track 304.Pq Fl u 305since they are not available to the file system for data allocation. 306This option is of historical importance only. Modern disks perform their own 307bad sector allocation. 308.It Fl r Ar revolutions/minute 309The speed of the disk in revolutions per minute. This value is no longer of 310interest, since all the parameters which depend on it are usually disabled. 311.It Fl t Ar #tracks/cylinder 312The number of tracks/cylinder available for data allocation by the file 313system. 314The default is 1. 315If zero is specified, the value from the disklabel will be used. 316.It Fl u Ar sectors/track 317The number of sectors per track available for data allocation by the file 318system. 319The default is 4096. 320If zero is specified, the value from the disklabel will be used. 321This does not include sectors reserved at the end of each track for bad 322block replacement (see the 323.Fl p 324option). 325.It Fl x Ar spare sectors per cylinder 326Spare sectors (bad sector replacements) are physical sectors that occupy 327space at the end of the last track in the cylinder. 328They are deducted from the sectors/track 329.Pq Fl u 330of the last track of each cylinder since they are not available to the file 331system for data allocation. 332This option is of historical importance only. Modern disks perform their own 333bad sector allocation. 334.El 335.Pp 336The options to the 337.Nm mount_mfs 338command are as described for the 339.Nm 340command, except for the 341.Fl o 342option. 343.Pp 344That option is as follows: 345.Bl -tag -width indent 346.It Fl o 347Options are specified with a 348.Fl o 349flag followed by a comma separated string of options. 350See the 351.Xr mount 8 352man page for possible options and their meanings. 353.El 354.Sh EXAMPLES 355.Dl newfs /dev/ad3s1a 356.Pp 357Creates a new ufs file system on 358.Pa ad3s1a . 359.Nm 360will use a block size of 16384 bytes, a fragment size of 2048 bytes 361and the largest possible number of cylinders per group. 362These values tend to produce better performance for most applications 363than the historical defaults 364(8192 byte block size and 1024 byte fragment size). 365This large fragment size 366may lead to large amounts of wasted space 367on filesystems that contain a large number of small files. 368.Pp 369.Dl mount_mfs -s 131072 -o nosuid,nodev,nosymfollow /dev/da0s1b /tmp 370.Pp 371Mount a 64 MB large memory file system on 372.Pa /tmp , 373with 374.Xr mount 8 375options 376.Ar nosuid , 377.Ar nodev , 378and 379.Ar nosymfollow . 380.Sh SEE ALSO 381.Xr fdformat 1 , 382.Xr disktab 5 , 383.Xr fs 5 , 384.Xr camcontrol 8 , 385.Xr disklabel 8 , 386.Xr diskpart 8 , 387.Xr dumpfs 8 , 388.Xr fsck 8 , 389.Xr mount 8 , 390.Xr tunefs 8 , 391.Xr vinum 8 392.Rs 393.%A M. McKusick 394.%A W. Joy 395.%A S. Leffler 396.%A R. Fabry 397.%T A Fast File System for UNIX 398.%J ACM Transactions on Computer Systems 2 399.%V 3 400.%P pp 181-197 401.%D August 1984 402.%O (reprinted in the BSD System Manager's Manual) 403.Re 404.Sh HISTORY 405The 406.Nm 407command appeared in 408.Bx 4.2 . 409